Implementing SQL ASSERTION

From 5e3f1190a9599bd10e40b2b310f1a597ef07c0e5 Mon Sep 17 00:00:00 2001
From: Joe Wildish <joe@elusive.cx>
Date: Sun, 14 Jan 2018 21:52:54 +0000
Subject: [PATCH] SQL assertion WIP

---
 doc/src/sgml/ddl.sgml                      |   31 +
 doc/src/sgml/ref/allfiles.sgml             |    3 +
 doc/src/sgml/ref/alter_assertion.sgml      |  139 ++++
 doc/src/sgml/ref/create_assertion.sgml     |  133 ++++
 doc/src/sgml/ref/drop_assertion.sgml       |  115 +++
 doc/src/sgml/reference.sgml                |    3 +
 src/backend/catalog/aclchk.c               |   31 +
 src/backend/catalog/information_schema.sql |   60 +-
 src/backend/catalog/namespace.c            |  121 +++
 src/backend/catalog/objectaddress.c        |   11 +
 src/backend/catalog/pg_constraint.c        |   20 +-
 src/backend/commands/alter.c               |    6 +
 src/backend/commands/constraint.c          | 1092 +++++++++++++++++++++++++++-
 src/backend/commands/event_trigger.c       |    2 +
 src/backend/nodes/copyfuncs.c              |   14 +
 src/backend/nodes/equalfuncs.c             |   12 +
 src/backend/parser/gram.y                  |   80 +-
 src/backend/parser/parse_agg.c             |    2 +
 src/backend/parser/parse_expr.c            |    2 +
 src/backend/parser/parse_func.c            |    4 +
 src/backend/tcop/utility.c                 |   20 +
 src/backend/utils/cache/lsyscache.c        |   19 +
 src/bin/psql/command.c                     |    3 +
 src/bin/psql/describe.c                    |   92 +++
 src/bin/psql/describe.h                    |    3 +
 src/bin/psql/help.c                        |    1 +
 src/bin/psql/tab-complete.c                |   28 +-
 src/include/catalog/namespace.h            |    1 +
 src/include/catalog/pg_constraint.h        |    3 +-
 src/include/catalog/pg_constraint_fn.h     |    2 +-
 src/include/catalog/pg_proc.h              |    4 +
 src/include/commands/constraint.h          |   10 +
 src/include/nodes/nodes.h                  |    1 +
 src/include/nodes/parsenodes.h             |   11 +
 src/include/parser/parse_node.h            |    1 +
 src/include/utils/acl.h                    |    2 +
 src/include/utils/lsyscache.h              |    1 +
 src/test/regress/expected/assertions.out   |  779 ++++++++++++++++++++
 src/test/regress/parallel_schedule         |    2 +-
 src/test/regress/serial_schedule           |    1 +
 src/test/regress/sql/assertions.sql        |  775 ++++++++++++++++++++
 41 files changed, 3571 insertions(+), 69 deletions(-)
 create mode 100644 doc/src/sgml/ref/alter_assertion.sgml
 create mode 100644 doc/src/sgml/ref/create_assertion.sgml
 create mode 100644 doc/src/sgml/ref/drop_assertion.sgml
 create mode 100644 src/include/commands/constraint.h
 create mode 100644 src/test/regress/expected/assertions.out
 create mode 100644 src/test/regress/sql/assertions.sql

diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml
index b1167a40e6..d8c0263a6a 100644
--- a/doc/src/sgml/ddl.sgml
+++ b/doc/src/sgml/ddl.sgml
@@ -917,6 +917,37 @@ CREATE TABLE circles (
     of the type specified in the constraint declaration.
    </para>
   </sect2>
+
+  <sect2 id="ddl-constraints-assertions">
+   <title>Assertions</title>
+   
+   <indexterm zone="ddl-constraints-assertions">
+    <primary>assertion</primary>
+   </indexterm>
+
+   <para>
+    An assertion is a constraint that is not part of a table
+    definition.  An assertion can define constraints that evaluate the
+    data across multiple rows of a table beyond what unique and
+    exclusion constraints can do, and assertions can look at the data
+    in multiple tables.
+   </para>
+
+   <para>
+    An assertion is a separate schema object and is created with the
+    command <command>CREATE ASSERTION</command>.  The constraint
+    expression is written as a <literal>CHECK</literal> clause like in
+    check constraints.  For instance, to ensure that there is always
+    at least one entry in the product table:
+<programlisting>
+CREATE ASSERTION products_not_empty CHECK ((SELECT count(*) FROM products) &gt; 0);
+</programlisting>
+    Assertions will often involve aggregate functions computed over
+    entire tables.  Note, however, that this kind of assertion can be
+   quite inefficient and should only be used on tables that are small
+    and change rarely.
+   </para>
+  </sect2>
  </sect1>
 
  <sect1 id="ddl-system-columns">
diff --git a/doc/src/sgml/ref/allfiles.sgml b/doc/src/sgml/ref/allfiles.sgml
index 22e6893211..57badaf157 100644
--- a/doc/src/sgml/ref/allfiles.sgml
+++ b/doc/src/sgml/ref/allfiles.sgml
@@ -7,6 +7,7 @@ Complete list of usable sgml source files in this directory.
 <!-- SQL commands -->
 <!ENTITY abort              SYSTEM "abort.sgml">
 <!ENTITY alterAggregate     SYSTEM "alter_aggregate.sgml">
+<!ENTITY alterAssertion     SYSTEM "alter_assertion.sgml">
 <!ENTITY alterCollation     SYSTEM "alter_collation.sgml">
 <!ENTITY alterConversion    SYSTEM "alter_conversion.sgml">
 <!ENTITY alterDatabase      SYSTEM "alter_database.sgml">
@@ -60,6 +61,7 @@ Complete list of usable sgml source files in this directory.
 <!ENTITY copyTable          SYSTEM "copy.sgml">
 <!ENTITY createAccessMethod SYSTEM "create_access_method.sgml">
 <!ENTITY createAggregate    SYSTEM "create_aggregate.sgml">
+<!ENTITY createAssertion    SYSTEM "create_assertion.sgml">
 <!ENTITY createCast         SYSTEM "create_cast.sgml">
 <!ENTITY createCollation    SYSTEM "create_collation.sgml">
 <!ENTITY createConversion   SYSTEM "create_conversion.sgml">
@@ -107,6 +109,7 @@ Complete list of usable sgml source files in this directory.
 <!ENTITY do                 SYSTEM "do.sgml">
 <!ENTITY dropAccessMethod   SYSTEM "drop_access_method.sgml">
 <!ENTITY dropAggregate      SYSTEM "drop_aggregate.sgml">
+<!ENTITY dropAssertion      SYSTEM "drop_assertion.sgml">
 <!ENTITY dropCast           SYSTEM "drop_cast.sgml">
 <!ENTITY dropCollation      SYSTEM "drop_collation.sgml">
 <!ENTITY dropConversion     SYSTEM "drop_conversion.sgml">
diff --git a/doc/src/sgml/ref/alter_assertion.sgml b/doc/src/sgml/ref/alter_assertion.sgml
new file mode 100644
index 0000000000..b06417f740
--- /dev/null
+++ b/doc/src/sgml/ref/alter_assertion.sgml
@@ -0,0 +1,139 @@
+<!--
+doc/src/sgml/ref/alter_assertion.sgml
+PostgreSQL documentation
+-->
+
+<refentry id="sql-alterassertion">
+
+ <indexterm zone="sql-alterassertion">
+  <primary>ALTER ASSERTION</primary>
+ </indexterm>
+
+ <refmeta>
+  <refentrytitle>ALTER ASSERTION</refentrytitle>
+  <manvolnum>7</manvolnum>
+  <refmiscinfo>SQL - Language Statements</refmiscinfo>
+ </refmeta>
+
+ <refnamediv>
+  <refname>ALTER ASSERTION</refname>
+  <refpurpose>change the definition of an assertion</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+<synopsis>
+ALTER ASSERTION <replaceable>name</replaceable> RENAME TO <replaceable>new_name</replaceable>
+ALTER ASSERTION <replaceable>name</replaceable> OWNER TO <replaceable>new_owner</replaceable>
+ALTER ASSERTION <replaceable>name</replaceable> SET SCHEMA <replaceable>new_schema</replaceable>
+</synopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+  <title>Description</title>
+
+  <para>
+   <command>ALTER ASSERTION</command> changes the definition of an
+   assertion.
+  </para>
+
+  <para>
+   You must own the assertion to use <command>ALTER ASSERTION</command>.  To
+   change the schema of an assertion, you must also have
+   <literal>CREATE</literal> privilege on the new schema.  To alter
+   the owner, you must also be a direct or indirect member of the new
+   owning role, and that role must have <literal>CREATE</literal>
+   privilege on the assertion's schema.  (These restrictions enforce
+   that altering the owner doesn't do anything you couldn't do by
+   dropping and recreating the assertion.  However, a superuser can
+   alter ownership of any assertion anyway.)
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Parameters</title>
+
+  <variablelist>
+   <varlistentry>
+    <term><replaceable class="parameter">name</replaceable></term>
+    <listitem>
+     <para>
+      The name (optionally schema-qualified) of an existing assertion.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><replaceable class="parameter">new_name</replaceable></term>
+    <listitem>
+     <para>
+      The new name of the assertion.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><replaceable class="parameter">new_owner</replaceable></term>
+    <listitem>
+     <para>
+      The new owner of the assertion.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><replaceable class="parameter">new_schema</replaceable></term>
+    <listitem>
+     <para>
+      The new schema for the assertion.
+     </para>
+    </listitem>
+   </varlistentry>
+  </variablelist>
+ </refsect1>
+
+ <refsect1>
+  <title>Examples</title>
+
+  <para>
+   To rename the assertuib <literal>check_size</literal>
+   to <literal>check_count</literal>:
+<programlisting>
+ALTER ASSERTION check_size RENAME TO check_count;
+</programlisting>
+  </para>
+
+  <para>
+   To change the owner of the assertion <literal>check_size</literal>
+   to <literal>joe</literal>:
+<programlisting>
+ALTER ASSERTION check_size OWNER TO joe;
+</programlisting>
+  </para>
+
+  <para>
+   To move the assertion <literal>check_size</literal> into
+   schema <literal>myschema</literal>:
+<programlisting>
+ALTER ASSERTION check_size SET SCHEMA myschema;
+</programlisting>
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Compatibility</title>
+
+  <para>
+   There is no <command>ALTER ASSERTION</command> statement in the SQL
+   standard.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>See Also</title>
+
+  <simplelist type="inline">
+   <member><xref linkend="sql-createassertion"/></member>
+   <member><xref linkend="sql-dropassertion"/></member>
+  </simplelist>
+ </refsect1>
+</refentry>
diff --git a/doc/src/sgml/ref/create_assertion.sgml b/doc/src/sgml/ref/create_assertion.sgml
new file mode 100644
index 0000000000..b36d1b4ecb
--- /dev/null
+++ b/doc/src/sgml/ref/create_assertion.sgml
@@ -0,0 +1,133 @@
+<!--
+doc/src/sgml/ref/create_assertion.sgml
+PostgreSQL documentation
+-->
+
+<refentry id="sql-createassertion">
+ <indexterm zone="sql-createassertion">
+  <primary>CREATE ASSERTION</primary>
+ </indexterm>
+
+ <refmeta>
+  <refentrytitle>CREATE ASSERTION</refentrytitle>
+  <manvolnum>7</manvolnum>
+  <refmiscinfo>SQL - Language Statements</refmiscinfo>
+ </refmeta>
+
+ <refnamediv>
+  <refname>CREATE ASSERTION</refname>
+  <refpurpose>define a new assertion</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+<synopsis>
+CREATE ASSERTION <replaceable class="parameter">name</replaceable> CHECK ( <replaceable class="parameter">name</replaceable> ) [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
+</synopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+  <title>Description</title>
+
+  <para>
+   <command>CREATE ASSERTION</command> creates an assertion.  An
+   assertion is a check constraint that is independent of a table row
+   and a table.  It can therefore be used to enforce more complex
+   constraints across multiple table rows and across multiple tables.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Parameters</title>
+
+  <variablelist>
+   <varlistentry>
+    <term><replaceable class="parameter">name</replaceable></term>
+    <listitem>
+     <para>
+      The name (optionally schema-qualified) of the assertion to
+      create.  Assertions use the same namespace as constraints on
+      tables.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>CHECK ( <replaceable class="parameter">expression</replaceable> )</literal></term>
+    <listitem>
+     <para>
+      The <literal>CHECK</literal> clause specifies an expression producing a
+      Boolean result which the database must satisfy at all times for a
+      data change operation to succeed.  Expressions evaluating
+      to TRUE or UNKNOWN succeed.  Should the result of a data change
+      operation produce a FALSE result an error exception is
+      raised and the change is not made.
+     </para>
+
+     <para>
+      The check expression typically involves subselects in order to
+      read data from tables.  See the examples below.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>DEFERRABLE</literal></term>
+    <term><literal>NOT DEFERRABLE</literal></term>
+    <term><literal>INITIALLY IMMEDIATE</literal></term>
+    <term><literal>INITIALLY DEFERRED</literal></term>
+    <listitem>
+     <para>
+      These clauses control the deferrability of the constraint.  See
+      <xref linkend="sql-createtable"/> for an explanation.
+     </para>
+    </listitem>
+   </varlistentry>
+  </variablelist>
+ </refsect1>
+
+ <refsect1>
+  <title>Notes</title>
+
+  <para>
+   More specialized constraint forms such as table check constraints,
+   foreign-key constraints, or exclusion constraints should be used
+   instead when applicable, because they will be more efficient.
+  </para>
+
+  <para>
+   Assertion checks are not specially optimized.  For example,
+   checking the row count of a large table in an assertion will be
+   just as slow as implementing the check manually.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Examples</title>
+
+  <para>
+   Check that the table <literal>table1</literal> has at most 30 rows:
+<programlisting>
+CREATE ASSERTION table1_max30 CHECK ((SELECT count(*) FROM table1) &lt;= 30);
+</programlisting>
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Compatibility</title>
+
+  <para>
+   <command>CREATE ASSERTION</command> conforms to the SQL standard.
+   The PostgreSQL implementation has certain restrictions on what
+   check expressions are allowed in assertions.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>See Also</title>
+
+  <simplelist type="inline">
+   <member><xref linkend="sql-alterassertion"/></member>
+   <member><xref linkend="sql-dropassertion"/></member>
+  </simplelist>
+ </refsect1>
+</refentry>
diff --git a/doc/src/sgml/ref/drop_assertion.sgml b/doc/src/sgml/ref/drop_assertion.sgml
new file mode 100644
index 0000000000..39a60a0d29
--- /dev/null
+++ b/doc/src/sgml/ref/drop_assertion.sgml
@@ -0,0 +1,115 @@
+<!--
+doc/src/sgml/ref/drop_assertion.sgml
+PostgreSQL documentation
+-->
+
+<refentry id="sql-dropassertion">
+
+ <indexterm zone="sql-dropassertion">
+  <primary>DROP ASSERTION</primary>
+ </indexterm>
+
+ <refmeta>
+  <refentrytitle>DROP ASSERTION</refentrytitle>
+  <manvolnum>7</manvolnum>
+  <refmiscinfo>SQL - Language Statements</refmiscinfo>
+ </refmeta>
+
+ <refnamediv>
+  <refname>DROP ASSERTION</refname>
+  <refpurpose>remove an assertion</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+<synopsis>
+DROP ASSERTION [ IF EXISTS ] <replaceable class="parameter">name</replaceable> [, ...] [ CASCADE | RESTRICT ]
+</synopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+  <title>Description</title>
+
+  <para>
+   <command>DROP ASSERTION</command> removes an existing assertion. To
+   execute this command the current user must be the owner of the
+   assertion.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Parameters</title>
+
+  <variablelist>
+
+   <varlistentry>
+    <term><literal>IF EXISTS</literal></term>
+    <listitem>
+     <para>
+      Do not throw an error if the assertion does not exist. A notice
+      is issued in this case.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><replaceable class="parameter">name</replaceable></term>
+    <listitem>
+     <para>
+      The name (optionally schema-qualified) of an existing assertion.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>CASCADE</literal></term>
+    <listitem>
+     <para>
+      Automatically drop objects that depend on the assertion.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>RESTRICT</literal></term>
+    <listitem>
+     <para>
+      Refuse to drop the assertion if any objects depend on it.  This
+      is the default.
+     </para>
+    </listitem>
+   </varlistentry>
+  </variablelist>
+ </refsect1>
+
+ <refsect1>
+  <title>Examples</title>
+
+  <para>
+   To remove the assertion <literal>check_size</literal>:
+<programlisting>
+DROP ASSERTION check_size;
+</programlisting>
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Compatibility</title>
+
+  <para>
+   This command conforms to the SQL standard, except that the standard
+   only allows one assertion to be dropped per command, and apart from
+   the <literal>IF EXISTS</literal> option, which is
+   a <productname>PostgreSQL</productname> extension.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>See Also</title>
+
+  <simplelist type="inline">
+   <member><xref linkend="sql-alterassertion"/></member>
+   <member><xref linkend="sql-createassertion"/></member>
+  </simplelist>
+ </refsect1>
+
+</refentry>
diff --git a/doc/src/sgml/reference.sgml b/doc/src/sgml/reference.sgml
index d27fb414f7..9300f2d9fc 100644
--- a/doc/src/sgml/reference.sgml
+++ b/doc/src/sgml/reference.sgml
@@ -35,6 +35,7 @@
 
    &abort;
    &alterAggregate;
+   &alterAssertion;
    &alterCollation;
    &alterConversion;
    &alterDatabase;
@@ -88,6 +89,7 @@
    &copyTable;
    &createAccessMethod;
    &createAggregate;
+   &createAssertion;
    &createCast;
    &createCollation;
    &createConversion;
@@ -135,6 +137,7 @@
    &do;
    &dropAccessMethod;
    &dropAggregate;
+   &dropAssertion;
    &dropCast;
    &dropCollation;
    &dropConversion;
diff --git a/src/backend/catalog/aclchk.c b/src/backend/catalog/aclchk.c
index fac80612b8..e32a0ad347 100644
--- a/src/backend/catalog/aclchk.c
+++ b/src/backend/catalog/aclchk.c
@@ -3376,6 +3376,8 @@ static const char *const no_priv_msg[MAX_ACL_KIND] =
 	gettext_noop("permission denied for operator family %s"),
 	/* ACL_KIND_COLLATION */
 	gettext_noop("permission denied for collation %s"),
+	/* ACL_KIND_CONSTRAINT */
+    gettext_noop("permission denied for constraint %s"),
 	/* ACL_KIND_CONVERSION */
 	gettext_noop("permission denied for conversion %s"),
 	/* ACL_KIND_STATISTICS */
@@ -3428,6 +3430,8 @@ static const char *const not_owner_msg[MAX_ACL_KIND] =
 	gettext_noop("must be owner of operator family %s"),
 	/* ACL_KIND_COLLATION */
 	gettext_noop("must be owner of collation %s"),
+	/* ACK_KIND_CONSTRAINT */
+	gettext_noop("must be owner of constraint %s"),
 	/* ACL_KIND_CONVERSION */
 	gettext_noop("must be owner of conversion %s"),
 	/* ACL_KIND_STATISTICS */
@@ -5067,6 +5071,33 @@ pg_collation_ownercheck(Oid coll_oid, Oid roleid)
 	return has_privs_of_role(roleid, ownerId);
 }
 
+/*
+ * Ownership check for a constraint (specified by OID).
+ */
+bool
+pg_constraint_ownercheck(Oid constr_oid, Oid roleid)
+{
+	HeapTuple   tuple;
+	//Oid           ownerId;
+
+	/* Superusers bypass all permission checking. */
+	if (superuser_arg(roleid))
+		return true;
+
+	tuple = SearchSysCache1(CONSTROID, ObjectIdGetDatum(constr_oid));
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+			    (errcode(ERRCODE_UNDEFINED_OBJECT),
+			     errmsg("constraint with OID %u does not exist", constr_oid)));
+
+	//FIXME: ownerId = ((Form_pg_constraint) GETSTRUCT(tuple))->conowner;
+
+	ReleaseSysCache(tuple);
+
+	//return has_privs_of_role(roleid, ownerId);
+	return true; // for now
+}
+
 /*
  * Ownership check for a conversion (specified by OID).
  */
diff --git a/src/backend/catalog/information_schema.sql b/src/backend/catalog/information_schema.sql
index 6fb1a1bc1c..9ef7cccdbb 100644
--- a/src/backend/catalog/information_schema.sql
+++ b/src/backend/catalog/information_schema.sql
@@ -285,7 +285,20 @@ GRANT SELECT ON administrable_role_authorizations TO PUBLIC;
  * ASSERTIONS view
  */
 
--- feature not supported
+CREATE VIEW assertions AS
+    SELECT CAST(current_database() AS sql_identifier) AS constraint_catalog,
+           CAST(n.nspname AS sql_identifier) AS constraint_schema,
+           CAST(con.conname AS sql_identifier) AS constraint_name,
+           CAST(CASE WHEN condeferrable THEN 'YES' ELSE 'NO' END
+             AS yes_or_no) AS is_deferrable,
+           CAST(CASE WHEN condeferred THEN 'YES' ELSE 'NO' END
+             AS yes_or_no) AS initially_deferred
+    FROM pg_namespace n, pg_constraint con
+    WHERE n.oid = con.connamespace
+          AND con.conrelid = 0 AND con.contypid = 0;
+          -- TODO: AND pg_has_role(con.conowner, 'USAGE');
+
+GRANT SELECT ON assertions TO PUBLIC;
 
 
 /*
@@ -790,7 +803,7 @@ CREATE VIEW constraint_column_usage AS
            CAST(cstrname AS sql_identifier) AS constraint_name
 
     FROM (
-        /* check constraints */
+        /* assertions and check constraints */
         SELECT DISTINCT nr.nspname, r.relname, r.relowner, a.attname, nc.nspname, c.conname
           FROM pg_namespace nr, pg_class r, pg_attribute a, pg_depend d, pg_namespace nc, pg_constraint c
           WHERE nr.oid = r.relnamespace
@@ -802,7 +815,7 @@ CREATE VIEW constraint_column_usage AS
             AND d.objid = c.oid
             AND c.connamespace = nc.oid
             AND c.contype = 'c'
-            AND r.relkind IN ('r', 'p')
+            AND r.relkind IN ('r', 'p', 'v')
             AND NOT a.attisdropped
 
         UNION ALL
@@ -842,20 +855,41 @@ GRANT SELECT ON constraint_column_usage TO PUBLIC;
 
 CREATE VIEW constraint_table_usage AS
     SELECT CAST(current_database() AS sql_identifier) AS table_catalog,
-           CAST(nr.nspname AS sql_identifier) AS table_schema,
-           CAST(r.relname AS sql_identifier) AS table_name,
+           CAST(tblschema AS sql_identifier) AS table_schema,
+           CAST(tblname AS sql_identifier) AS table_name,
            CAST(current_database() AS sql_identifier) AS constraint_catalog,
-           CAST(nc.nspname AS sql_identifier) AS constraint_schema,
-           CAST(c.conname AS sql_identifier) AS constraint_name
+           CAST(cstrschema AS sql_identifier) AS constraint_schema,
+           CAST(cstrname AS sql_identifier) AS constraint_name
+
+    FROM (
+        /* assertions and check constraints */
+        SELECT DISTINCT nr.nspname, r.relname, r.relowner, nc.nspname, c.conname
+          FROM pg_namespace nr, pg_class r,
+               pg_depend d, pg_namespace nc, pg_constraint c
+         WHERE nr.oid = r.relnamespace
+           AND d.refobjid = r.oid
+           AND c.connamespace = nc.oid
+           AND d.objid = c.oid
+           AND d.refclassid = 'pg_catalog.pg_class'::regclass
+           AND d.classid = 'pg_catalog.pg_constraint'::regclass
+           AND c.contype = 'c'
+           AND r.relkind IN ('r', 'p', 'v')
 
-    FROM pg_constraint c, pg_namespace nc,
-         pg_class r, pg_namespace nr
+        UNION ALL
 
-    WHERE c.connamespace = nc.oid AND r.relnamespace = nr.oid
-          AND ( (c.contype = 'f' AND c.confrelid = r.oid)
+        /* unique/primary key constraints */
+        SELECT nr.nspname, r.relname, r.relowner, nc.nspname, c.conname
+          FROM pg_constraint c, pg_namespace nc,
+               pg_class r, pg_namespace nr
+         WHERE c.connamespace = nc.oid
+           AND r.relnamespace = nr.oid
+           AND ( (c.contype = 'f' AND c.confrelid = r.oid)
              OR (c.contype IN ('p', 'u') AND c.conrelid = r.oid) )
-          AND r.relkind IN ('r', 'p')
-          AND pg_has_role(r.relowner, 'USAGE');
+           AND r.relkind IN ('r', 'p')
+
+    ) AS x (tblschema, tblname, tblowner, cstrschema, cstrname)
+
+    WHERE pg_has_role(x.tblowner, 'USAGE');
 
 GRANT SELECT ON constraint_table_usage TO PUBLIC;
 
diff --git a/src/backend/catalog/namespace.c b/src/backend/catalog/namespace.c
index 93c4bbfcb0..17fe756979 100644
--- a/src/backend/catalog/namespace.c
+++ b/src/backend/catalog/namespace.c
@@ -27,6 +27,7 @@
 #include "catalog/objectaccess.h"
 #include "catalog/pg_authid.h"
 #include "catalog/pg_collation.h"
+#include "catalog/pg_constraint.h"
 #include "catalog/pg_conversion.h"
 #include "catalog/pg_conversion_fn.h"
 #include "catalog/pg_namespace.h"
@@ -57,9 +58,11 @@
 #include "utils/lsyscache.h"
 #include "utils/memutils.h"
 #include "utils/syscache.h"
+#include "utils/fmgroids.h"
 #include "utils/varlena.h"
 
 
+
 /*
  * The namespace search path is a possibly-empty list of namespace OIDs.
  * In addition to the explicit list, implicitly-searched namespaces
@@ -3483,6 +3486,124 @@ PopOverrideSearchPath(void)
 }
 
 
+static Oid
+get_assertion_oid_internal(Relation pg_constraint, char *assertion_name, Oid namespaceId, List *name)
+{
+	SysScanDesc scan;
+	ScanKeyData skey[4];
+	HeapTuple	tuple;
+	Oid			conOid = InvalidOid;
+
+	ScanKeyInit(&skey[0],
+				Anum_pg_constraint_conname,
+				BTEqualStrategyNumber, F_NAMEEQ,
+				PointerGetDatum(assertion_name));
+
+	ScanKeyInit(&skey[1],
+				Anum_pg_constraint_connamespace,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(namespaceId));
+
+	ScanKeyInit(&skey[2],
+				Anum_pg_constraint_conrelid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				InvalidOid);
+
+	ScanKeyInit(&skey[3],
+				Anum_pg_constraint_contypid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				InvalidOid);
+
+	scan = systable_beginscan(pg_constraint, InvalidOid, false,
+							  NULL, 4, skey);
+
+	/*
+	 * Fetch the constraint tuple from pg_constraint.  There may be
+	 * more than one match, because constraints are not required to
+	 * have unique names; if so, error out.
+	 */
+	while (HeapTupleIsValid(tuple = systable_getnext(scan)))
+	{
+		Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(tuple);
+
+		if (OidIsValid(con->conrelid) || OidIsValid(con->contypid))
+			ereport(ERROR,
+					(errmsg("constraint \"%s\" is not an assertion",
+							NameListToString(name))));
+
+		if (strcmp(NameStr(con->conname), assertion_name) == 0)
+		{
+			if (OidIsValid(conOid))
+				ereport(ERROR,
+						(errcode(ERRCODE_DUPLICATE_OBJECT),
+								errmsg("there are multiple assertions named \"%s\"",
+									   NameListToString(name))));
+			conOid = HeapTupleGetOid(tuple);
+		}
+	}
+
+	systable_endscan(scan);
+
+	return conOid;
+}
+
+/*
+ * get_assertion_oid
+ *		Find an assertion with the specified name.
+ *		Returns constraint's OID.
+ */
+Oid
+get_assertion_oid(List *name, bool missing_ok)
+{
+	char	   *schemaname;
+	char	   *assertion_name;
+	Oid			namespaceId;
+	Relation	pg_constraint;
+	Oid			conOid = InvalidOid;
+
+	DeconstructQualifiedName(name, &schemaname, &assertion_name);
+
+	pg_constraint = heap_open(ConstraintRelationId, AccessShareLock);
+
+	if (schemaname)
+	{
+		namespaceId = LookupExplicitNamespace(schemaname, missing_ok);
+		conOid = get_assertion_oid_internal(pg_constraint, assertion_name, namespaceId, name);
+	}
+	else
+	{
+		ListCell   *l;
+
+		recomputeNamespacePath();
+
+		foreach(l, activeSearchPath)
+		{
+			namespaceId = lfirst_oid(l);
+
+			if (namespaceId == myTempNamespace)
+				continue;		/* do not look in temp namespace */
+
+			conOid = get_assertion_oid_internal(pg_constraint, assertion_name, namespaceId, name);
+
+			if (OidIsValid(conOid))
+				break;
+		}
+	}
+
+	heap_close(pg_constraint, AccessShareLock);
+
+	/* If no such constraint exists, complain */
+	if (!OidIsValid(conOid) && !missing_ok)
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+						errmsg("assertion \"%s\" does not exist",
+							   NameListToString(name))));
+
+	return conOid;
+}
+
+
+
 /*
  * get_collation_oid - find a collation by possibly qualified name
  *
diff --git a/src/backend/catalog/objectaddress.c b/src/backend/catalog/objectaddress.c
index bc999ca3c4..daa9acf4e4 100644
--- a/src/backend/catalog/objectaddress.c
+++ b/src/backend/catalog/objectaddress.c
@@ -899,6 +899,11 @@ get_object_address(ObjectType objtype, Node *object,
 				address.objectId = LookupOperWithArgs(castNode(ObjectWithArgs, object), missing_ok);
 				address.objectSubId = 0;
 				break;
+			case OBJECT_ASSERTION:
+				address.classId = ConstraintRelationId;
+				address.objectId = get_assertion_oid(castNode(List, object), missing_ok);
+				address.objectSubId = 0;
+				break;
 			case OBJECT_COLLATION:
 				address.classId = CollationRelationId;
 				address.objectId = get_collation_oid(castNode(List, object), missing_ok);
@@ -2114,6 +2119,7 @@ pg_get_object_address(PG_FUNCTION_ARGS)
 		case OBJECT_FOREIGN_TABLE:
 		case OBJECT_COLUMN:
 		case OBJECT_ATTRIBUTE:
+		case OBJECT_ASSERTION:
 		case OBJECT_COLLATION:
 		case OBJECT_CONVERSION:
 		case OBJECT_STATISTIC_EXT:
@@ -2274,6 +2280,11 @@ check_object_ownership(Oid roleid, ObjectType objtype, ObjectAddress address,
 				aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_NAMESPACE,
 							   strVal((Value *) object));
 			break;
+		case OBJECT_ASSERTION:
+			if (!pg_constraint_ownercheck(address.objectId, roleid))
+				aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CONSTRAINT,
+							   NameListToString(castNode(List, object)));
+			break;
 		case OBJECT_COLLATION:
 			if (!pg_collation_ownercheck(address.objectId, roleid))
 				aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_COLLATION,
diff --git a/src/backend/catalog/pg_constraint.c b/src/backend/catalog/pg_constraint.c
index 442ae7e23d..52a5a7efec 100644
--- a/src/backend/catalog/pg_constraint.c
+++ b/src/backend/catalog/pg_constraint.c
@@ -429,6 +429,13 @@ ConstraintNameIsUsed(ConstraintCategory conCat, Oid objId,
 			found = true;
 			break;
 		}
+		else if (conCat == CONSTRAINT_ASSERTION
+				 && con->conrelid == InvalidOid
+				 && con->contypid == InvalidOid)
+		{
+			found = true;
+			break;
+		}
 	}
 
 	systable_endscan(conscan);
@@ -600,8 +607,7 @@ RemoveConstraintById(Oid conId)
 		 * but we have no such concept at the moment.
 		 */
 	}
-	else
-		elog(ERROR, "constraint %u is not of a known type", conId);
+	/* Else it's an assertion; nothing special for that. */
 
 	/* Fry the constraint itself */
 	CatalogTupleDelete(conDesc, &tup->t_self);
@@ -657,6 +663,16 @@ RenameConstraintById(Oid conId, const char *newname)
 				(errcode(ERRCODE_DUPLICATE_OBJECT),
 				 errmsg("constraint \"%s\" for domain %s already exists",
 						newname, format_type_be(con->contypid))));
+	if (!OidIsValid(con->conrelid) &&
+		!OidIsValid(con->contypid) &&
+		ConstraintNameIsUsed(CONSTRAINT_ASSERTION,
+							 InvalidOid,
+							 con->connamespace,
+							 newname))
+		ereport(ERROR,
+				(errcode(ERRCODE_DUPLICATE_OBJECT),
+						errmsg("assertion \"%s\" already exists",
+							   newname)));
 
 	/* OK, do the rename --- tuple is a copy, so OK to scribble on it */
 	namestrcpy(&(con->conname), newname);
diff --git a/src/backend/commands/alter.c b/src/backend/commands/alter.c
index 3995c5ef3d..66ba6cbd30 100644
--- a/src/backend/commands/alter.c
+++ b/src/backend/commands/alter.c
@@ -41,6 +41,7 @@
 #include "commands/alter.h"
 #include "commands/collationcmds.h"
 #include "commands/conversioncmds.h"
+#include "commands/constraint.h"
 #include "commands/dbcommands.h"
 #include "commands/defrem.h"
 #include "commands/event_trigger.h"
@@ -326,6 +327,9 @@ ExecRenameStmt(RenameStmt *stmt)
 {
 	switch (stmt->renameType)
 	{
+		case OBJECT_ASSERTION:
+			return RenameAssertion(stmt);
+
 		case OBJECT_TABCONSTRAINT:
 		case OBJECT_DOMCONSTRAINT:
 			return RenameConstraint(stmt);
@@ -491,6 +495,7 @@ ExecAlterObjectSchemaStmt(AlterObjectSchemaStmt *stmt,
 
 			/* generic code path */
 		case OBJECT_AGGREGATE:
+		case OBJECT_ASSERTION:
 		case OBJECT_COLLATION:
 		case OBJECT_CONVERSION:
 		case OBJECT_FUNCTION:
@@ -838,6 +843,7 @@ ExecAlterOwnerStmt(AlterOwnerStmt *stmt)
 
 			/* Generic cases */
 		case OBJECT_AGGREGATE:
+		case OBJECT_ASSERTION:
 		case OBJECT_COLLATION:
 		case OBJECT_CONVERSION:
 		case OBJECT_FUNCTION:
diff --git a/src/backend/commands/constraint.c b/src/backend/commands/constraint.c
index 90f19ad3dd..969ce6deff 100644
--- a/src/backend/commands/constraint.c
+++ b/src/backend/commands/constraint.c
@@ -11,6 +11,8 @@
  *
  *-------------------------------------------------------------------------
  */
+
+
 #include "postgres.h"
 
 #include "catalog/index.h"
@@ -20,6 +22,40 @@
 #include "utils/rel.h"
 #include "utils/tqual.h"
 
+#include "access/htup_details.h"
+#include "catalog/dependency.h"
+#include "catalog/namespace.h"
+#include "catalog/pg_aggregate.h"
+#include "catalog/pg_constraint.h"
+#include "catalog/pg_constraint_fn.h"
+#include "catalog/pg_operator.h"
+#include "catalog/pg_proc.h"
+#include "catalog/pg_language.h"
+#include "catalog/pg_trigger.h"
+#include "catalog/pg_type.h"
+#include "commands/constraint.h"
+#include "executor/functions.h"
+#include "executor/spi.h"
+#include "miscadmin.h"
+#include "nodes/makefuncs.h"
+#include "nodes/nodeFuncs.h"
+#include "optimizer/planner.h"
+#include "parser/analyze.h"
+#include "parser/parse_coerce.h"
+#include "parser/parse_expr.h"
+#include "parser/parse_node.h"
+#include "parser/parse_relation.h"
+#include "parser/parser.h"
+#include "parser/parsetree.h"
+#include "rewrite/rewriteHandler.h"
+#include "tcop/tcopprot.h"
+#include "utils/acl.h"
+#include "utils/lsyscache.h"
+#include "utils/snapmgr.h"
+#include "utils/syscache.h"
+#include "utils/ruleutils.h"
+#include "utils/fmgroids.h"
+
 
 /*
  * unique_key_recheck - trigger function to do a deferred uniqueness check.
@@ -39,15 +75,15 @@ unique_key_recheck(PG_FUNCTION_ARGS)
 {
 	TriggerData *trigdata = castNode(TriggerData, fcinfo->context);
 	const char *funcname = "unique_key_recheck";
-	HeapTuple	new_row;
+	HeapTuple new_row;
 	ItemPointerData tmptid;
-	Relation	indexRel;
-	IndexInfo  *indexInfo;
-	EState	   *estate;
+	Relation indexRel;
+	IndexInfo *indexInfo;
+	EState *estate;
 	ExprContext *econtext;
 	TupleTableSlot *slot;
-	Datum		values[INDEX_MAX_KEYS];
-	bool		isnull[INDEX_MAX_KEYS];
+	Datum values[INDEX_MAX_KEYS];
+	bool isnull[INDEX_MAX_KEYS];
 
 	/*
 	 * Make sure this is being called as an AFTER ROW trigger.  Note:
@@ -57,15 +93,15 @@ unique_key_recheck(PG_FUNCTION_ARGS)
 	if (!CALLED_AS_TRIGGER(fcinfo))
 		ereport(ERROR,
 				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
-				 errmsg("function \"%s\" was not called by trigger manager",
-						funcname)));
+					errmsg("function \"%s\" was not called by trigger manager",
+						   funcname)));
 
 	if (!TRIGGER_FIRED_AFTER(trigdata->tg_event) ||
 		!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
 		ereport(ERROR,
 				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
-				 errmsg("function \"%s\" must be fired AFTER ROW",
-						funcname)));
+					errmsg("function \"%s\" must be fired AFTER ROW",
+						   funcname)));
 
 	/*
 	 * Get the new data that was inserted/updated.
@@ -78,9 +114,9 @@ unique_key_recheck(PG_FUNCTION_ARGS)
 	{
 		ereport(ERROR,
 				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
-				 errmsg("function \"%s\" must be fired for INSERT or UPDATE",
-						funcname)));
-		new_row = NULL;			/* keep compiler quiet */
+					errmsg("function \"%s\" must be fired for INSERT or UPDATE",
+						   funcname)));
+		new_row = NULL;            /* keep compiler quiet */
 	}
 
 	/*
@@ -194,3 +230,1033 @@ unique_key_recheck(PG_FUNCTION_ARGS)
 
 	return PointerGetDatum(NULL);
 }
+
+
+static void
+test_assertion_expr(char *name, char *expression)
+{
+	char *sql;
+	int returnCode;
+	bool isNull;
+	Datum value;
+
+	if (SPI_connect() != SPI_OK_CONNECT)
+		elog(ERROR, "SPI connect failed when executing ASSERTION statement");
+
+	sql = psprintf("SELECT %s", expression);
+	returnCode = SPI_exec(sql, 1);
+
+	if (returnCode > 0 && SPI_tuptable != NULL)
+	{
+		value = SPI_getbinval(SPI_tuptable->vals[0], SPI_tuptable->tupdesc, 1, &isNull);
+		if (isNull)
+			ereport(ERROR,
+					(errcode(ERRCODE_CHECK_VIOLATION),
+							errmsg("assertion \"%s\" truth is unknown", name)));
+		else if (!isNull && !DatumGetBool(value))
+			ereport(ERROR,
+					(errcode(ERRCODE_CHECK_VIOLATION),
+							errmsg("assertion \"%s\" violated", name)));
+	}
+	else
+		elog(ERROR, "unexpected SPI result when executing ASSERTION statement");
+
+	SPI_finish();
+}
+
+
+Datum
+assertion_check(PG_FUNCTION_ARGS)
+{
+	TriggerData *trigdata = (TriggerData *) fcinfo->context;
+	const char *funcname = "assertion_check";
+	Oid constraintOid;
+	HeapTuple tup;
+	Datum adatum;
+	bool isNull;
+
+	/*
+	 * Make sure this is being called as an AFTER STATEMENT trigger.	Note:
+	 * translatable error strings are shared with ri_triggers.c, so resist the
+	 * temptation to fold the function name into them.
+	 */
+	if (!CALLED_AS_TRIGGER(fcinfo))
+		ereport(ERROR,
+				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
+					errmsg("function \"%s\" was not called by trigger manager",
+						   funcname)));
+
+	if (!TRIGGER_FIRED_AFTER(trigdata->tg_event) ||
+		!TRIGGER_FIRED_FOR_STATEMENT(trigdata->tg_event))
+		ereport(ERROR,
+				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
+					errmsg("function \"%s\" must be fired AFTER STATEMENT",
+						   funcname)));
+
+	constraintOid = trigdata->tg_trigger->tgconstraint;
+	tup = SearchSysCache1(CONSTROID, ObjectIdGetDatum(constraintOid));
+	if (!HeapTupleIsValid(tup))
+		elog(ERROR, "cache lookup failed for constraint %u", constraintOid);
+
+	// XXX bogus
+	adatum = SysCacheGetAttr(CONSTROID, tup,
+							 Anum_pg_constraint_consrc, &isNull);
+	if (isNull)
+		elog(ERROR, "constraint %u has null consrc", constraintOid);
+
+	test_assertion_expr(get_constraint_name(constraintOid), TextDatumGetCString(adatum));
+
+	ReleaseSysCache(tup);
+	return PointerGetDatum(NULL);
+}
+
+#define NO_FUNC				(0)
+#define OTHER_FUNC			(1 << 0)
+#define MIN_AGG_FUNC		(1 << 1)
+#define MAX_AGG_FUNC		(1 << 2)
+#define COUNT_AGG_FUNC		(1 << 3)
+#define EVERY_AGG_FUNC		(1 << 4)
+#define BOOL_AND_AGG_FUNC	(1 << 5)
+#define BOOL_OR_AGG_FUNC	(1 << 6)
+
+#define EQ_COMPARISONS 		(bms_make_singleton(ROWCOMPARE_EQ))
+#define NE_COMPARISONS 		(bms_make_singleton(ROWCOMPARE_NE))
+#define LTE_COMPARISONS 	(bms_add_member(bms_make_singleton(ROWCOMPARE_LE), ROWCOMPARE_LT))
+#define GTE_COMPARISONS 	(bms_add_member(bms_make_singleton(ROWCOMPARE_GE), ROWCOMPARE_GT))
+
+#define MatchesOnly(a,b)	(((a) & (b)) && !((a) & (~(b))))
+#define CanOptimise(s) 		(!bms_is_empty(s) && \
+							(bms_is_subset(s, EQ_COMPARISONS)  || \
+							 bms_is_subset(s, NE_COMPARISONS)  || \
+							 bms_is_subset(s, LTE_COMPARISONS) || \
+							 bms_is_subset(s, GTE_COMPARISONS) ))
+
+
+// TODO review TODOs in the tests
+// TODO assertions should allow unknown according to the SQL specification
+// TODO traversal into views needs rethinking - dependencies?
+// TODO pg_dump support
+
+/*
+ * DML operations that could affect the truth of an assertion. Only
+ * INSERT and DELETE are considered as part of the labeling algorithm.
+ * UPDATEs are inferred using different logic.
+ */
+typedef enum DmlOp
+{
+	INSERT,
+	DELETE,
+	INSERT_DELETE
+} DmlOp;
+
+
+/*
+ * A context used to capture operations that may invalidate an assertion.
+ */
+typedef struct AssertionInfo
+{
+	DmlOp	label;         /* current invaliding operation */
+	Expr   *expr;          /* current Expression node */
+	List   *rtable;        /* current range tables */
+	List   *operators;     /* current operators */
+	SetOperation setOp;         /* current set-operation */
+	bool	invert;		   /* ... */
+	bool	inView;        /* if the walker has entered a view */
+	bool	inTargetEntry; /* if the walker has entered a TargetEntry node */
+	bool	inComparison;  /* if the walker has entered a comparison operation */
+	bool	inExists;      /* if the walker has entered an EXISTS node */
+
+	List   *dependencies; /* ... */
+	List   *relations;    /* relation Oids for all tables involved in the assertion check */
+	List   *inserts;      /* relation Oids for which INSERT could invalidate the assertion */
+	List   *deletes;      /* relation Oids for which DELETE could invalidate the assertion */
+	List   *updates;      /* relation Oids for which UPDATE could invalidate the assertion */
+	List   *columns;      /* list of ObjectAddresses referencing involved columns */
+} AssertionInfo;
+
+
+static void initAssertionInfo(AssertionInfo *info);
+static void copyAssertionInfo(AssertionInfo *target, AssertionInfo *source);
+static DmlOp oppositeDmlOp(DmlOp operation);
+static RowCompareType oppositeCompareType(RowCompareType type);
+static DmlOp labelForComparisonWithAggFuncs(DmlOp label, RowCompareType compOp, int aggFuncs);
+static int16 triggerOnEvents(AssertionInfo *info, Oid relationId);
+static List *triggerOnColumns(AssertionInfo *info, Oid relationId);
+static bool listContainsObjectAddress(List *list, ObjectAddress *address);
+static Bitmapset * strategiesForOperators(List *operators);
+static int functionsForTargetList(List *targetList);
+static int funcMaskForFuncOid(Oid funcOid);
+static Query * queryForSQLFunction(FuncExpr *funcExpr);
+
+/* Expression visiting */
+static bool visitAllNodes(Node *node, AssertionInfo *info);
+static bool visitRangeTblRef(RangeTblRef *node, AssertionInfo *info);
+static bool visitQuery(Query *node, AssertionInfo *info);
+static bool visitSetOperationStmt(SetOperationStmt *node, AssertionInfo *info);
+static bool visitBoolExpr(BoolExpr *node, AssertionInfo *info);
+static bool visitSubLink(SubLink *node, AssertionInfo *info);
+static bool visitFuncExpr(FuncExpr *node, AssertionInfo *info);
+static bool visitExpr(Expr *node, AssertionInfo *info);
+static bool visitVar(Var *node, AssertionInfo *info);
+
+/* TargetList visiting */
+static bool visitAggrefNodes(Node *node, int *aggFuncs);
+static bool visitAggref(Aggref *node, int *aggFuncs);
+static bool visitWindowFunc(WindowFunc *node, int *aggFuncs);
+
+
+static void
+initAssertionInfo(AssertionInfo *info)
+{
+	info->label = DELETE;
+	info->expr = NULL;
+	info->rtable = NIL;
+	info->operators = NIL;
+	info->setOp = SETOP_NONE;
+	info->invert = false;
+	info->inView = false;
+	info->inTargetEntry = false;
+	info->inComparison = false;
+	info->inExists = false;
+
+	info->dependencies = NIL;
+	info->relations = NIL;
+	info->inserts = NIL;
+	info->deletes = NIL;
+	info->updates = NIL;
+	info->columns = NIL;
+}
+
+
+static void
+copyAssertionInfo(AssertionInfo *target, AssertionInfo *source)
+{
+	target->label = source->label;
+	target->expr = source->expr;
+	target->rtable = source->rtable;
+	target->operators = source->operators;
+	target->setOp = source->setOp;
+	target->invert = source->invert;
+	target->inView = source->inView;
+	target->inTargetEntry = source->inTargetEntry;
+	target->inComparison = source->inComparison;
+	target->inExists = source->inExists;
+}
+
+
+static DmlOp
+oppositeDmlOp(DmlOp operation)
+{
+	switch (operation)
+	{
+		case INSERT:
+			return DELETE;
+		case DELETE:
+			return INSERT;
+		case INSERT_DELETE:
+			return INSERT_DELETE;
+	}
+}
+
+
+static RowCompareType
+oppositeCompareType(RowCompareType type)
+{
+	switch (type)
+	{
+		case ROWCOMPARE_LE:
+			return ROWCOMPARE_GE;
+		case ROWCOMPARE_LT:
+			return ROWCOMPARE_GT;
+		case ROWCOMPARE_GT:
+			return ROWCOMPARE_LT;
+		case ROWCOMPARE_GE:
+			return ROWCOMPARE_LE;
+		default:
+			return type; /* we do not flip EQ and NE comparisons */
+	}
+}
+
+
+static DmlOp
+labelForComparisonWithAggFuncs(DmlOp label, RowCompareType compOp, int aggFuncs)
+{
+	int stronger, weaker;
+
+	switch (compOp)
+	{
+		case ROWCOMPARE_LT:
+		case ROWCOMPARE_LE:
+			stronger = MIN_AGG_FUNC;
+			weaker = MAX_AGG_FUNC | COUNT_AGG_FUNC;
+			break;
+
+		case ROWCOMPARE_EQ:
+			stronger = BOOL_AND_AGG_FUNC | EVERY_AGG_FUNC;
+			weaker = BOOL_OR_AGG_FUNC;
+			break;
+
+		case ROWCOMPARE_NE:
+			stronger = BOOL_AND_AGG_FUNC | EVERY_AGG_FUNC;
+			weaker = BOOL_OR_AGG_FUNC;
+			break;
+
+		case ROWCOMPARE_GE:
+		case ROWCOMPARE_GT:
+			stronger = MAX_AGG_FUNC | COUNT_AGG_FUNC;
+			weaker = MIN_AGG_FUNC;
+			break;
+
+		default:
+			stronger = weaker = NO_FUNC;
+	}
+
+	if (MatchesOnly(aggFuncs, weaker))
+		return label;
+	else if (MatchesOnly(aggFuncs, stronger))
+		return oppositeDmlOp(label);
+	else
+		return INSERT_DELETE;
+}
+
+
+static int16
+triggerOnEvents(AssertionInfo *info, Oid relationId)
+{
+	int16 result = 0;
+	if (list_member_oid(info->inserts, relationId))
+		result |= TRIGGER_TYPE_INSERT;
+	if (list_member_oid(info->deletes, relationId))
+		result |= TRIGGER_TYPE_DELETE | TRIGGER_TYPE_TRUNCATE;
+	if (list_member_oid(info->updates, relationId))
+		result |= TRIGGER_TYPE_UPDATE;
+	return result;
+}
+
+
+/*
+ * Returns a list of string nodes, suitable for use in the trigger
+ * definition, that contain the column names to be triggered against
+ * on UPDATE operations.
+ */
+static List *
+triggerOnColumns(AssertionInfo *info, Oid relationId)
+{
+	List     	  *columns = NIL;
+	ListCell 	  *cell;
+
+	foreach(cell, info->columns)
+	{
+		ObjectAddress *column = (ObjectAddress *) lfirst(cell);
+		AttrNumber attrNumber = (AttrNumber) column->objectSubId;
+
+		if (column->objectId == relationId)
+		{
+			Value *name = makeString(get_attname(relationId, attrNumber));
+			columns = lappend(columns, name);
+		}
+	}
+
+	return columns;
+}
+
+
+static bool
+listContainsObjectAddress(List *list, ObjectAddress *address)
+{
+	ListCell 	  *cell;
+	ObjectAddress *item;
+
+	foreach(cell, list)
+	{
+		item = (ObjectAddress *) lfirst(cell);
+		if (item->classId == address->classId &&
+			item->objectId == address->objectId &&
+			item->objectSubId == address->objectSubId)
+			return true;
+	}
+
+	return false;
+}
+
+
+static Bitmapset *
+strategiesForOperators(List *operators)
+{
+	ListCell  *operatorCell;
+	Bitmapset *strategies = NULL;
+
+	foreach(operatorCell, operators)
+	{
+		Oid operator = lfirst_oid(operatorCell);
+		List *interpretations = get_op_btree_interpretation(operator);
+		ListCell *interpretationCell;
+
+		foreach(interpretationCell, interpretations)
+			strategies = bms_add_member(strategies,
+										((OpBtreeInterpretation *) lfirst(interpretationCell))->strategy);
+	}
+
+	return strategies;
+}
+
+
+static int
+functionsForTargetList(List *targetList)
+{
+	int functionMask = NO_FUNC;
+	expression_tree_walker((Node *) targetList, visitAggrefNodes, &functionMask);
+	return functionMask;
+}
+
+
+static int
+funcMaskForFuncOid(Oid funcOid)
+{
+	char *name = get_func_name(funcOid);
+
+	if (name == NULL)
+		return OTHER_FUNC;
+	else if (strncmp(name, "min", strlen("min")) == 0)
+		return MIN_AGG_FUNC;
+	else if (strncmp(name, "max", strlen("max")) == 0)
+		return MAX_AGG_FUNC;
+	else if (strncmp(name, "count", strlen("count")) == 0)
+		return COUNT_AGG_FUNC;
+	else if (strncmp(name, "every", strlen("every")) == 0)
+		return EVERY_AGG_FUNC;
+	else if (strncmp(name, "bool_and", strlen("bool_and")) == 0)
+		return BOOL_AND_AGG_FUNC;
+	else if (strncmp(name, "bool_or", strlen("bool_or")) == 0)
+		return BOOL_OR_AGG_FUNC;
+	else
+		return OTHER_FUNC;
+}
+
+
+static Query *
+queryForSQLFunction(FuncExpr *funcExpr)
+{
+	Oid			funcId;
+	Relation 	procRel;
+	HeapTuple	tuple;
+	Datum		datum;
+	bool		isNull;
+	char	   *sql;
+	List	   *rawParseTree;
+	ParseState *pstate;
+	Query	   *query;
+	SQLFunctionParseInfoPtr pinfo;
+
+	funcId = funcExpr->funcid;
+	procRel = heap_open(ProcedureRelationId, ShareLock);
+
+	tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcId));
+	if (!HeapTupleIsValid(tuple))
+		elog(ERROR, "cache lookup failed for function %u", funcId);
+
+	datum = SysCacheGetAttr(PROCOID,
+							tuple,
+							Anum_pg_proc_prosrc,
+							&isNull);
+	if (isNull)
+		elog(ERROR, "null prosrc for function %u", funcId);
+
+	sql = TextDatumGetCString(datum);
+	rawParseTree = pg_parse_query(sql);
+
+	pinfo = prepare_sql_fn_parse_info(tuple,
+									  (Node *) funcExpr,
+									  funcExpr->inputcollid);
+
+	pstate = make_parsestate(NULL);
+	pstate->p_sourcetext = sql;
+	sql_fn_parser_setup(pstate, pinfo);
+
+	query = transformTopLevelStmt(pstate, linitial(rawParseTree));
+	free_parsestate(pstate);
+
+	ReleaseSysCache(tuple);
+	heap_close(procRel, NoLock);
+
+	return query;
+}
+
+
+static bool
+visitRangeTblRef(RangeTblRef *node, AssertionInfo *info)
+{
+	RangeTblEntry  *entry;
+	Oid				relationId;
+	RTEKind			rtekind;
+	char 		    relkind;
+	bool			result;
+
+	entry = rt_fetch(node->rtindex, info->rtable);
+	rtekind = entry->rtekind;
+	result = false;
+
+	if (rtekind == RTE_RELATION)
+	{
+		relationId = getrelid(node->rtindex, info->rtable);
+		relkind = get_rel_relkind(relationId);
+
+		if (relkind == RELKIND_RELATION)
+		{
+			if (info->label == INSERT || info->label == INSERT_DELETE)
+				info->inserts = list_append_unique_oid(info->inserts, relationId);
+
+			if (info->label == DELETE || info->label == INSERT_DELETE)
+				info->deletes = list_append_unique_oid(info->deletes, relationId);
+
+			if (!info->inView)
+				info->dependencies = list_append_unique_oid(info->dependencies, relationId);
+
+			info->relations = list_append_unique_oid(info->relations, relationId);
+
+		}
+		else if (relkind == RELKIND_VIEW)
+		{
+			Relation view = heap_open(relationId, AccessShareLock);
+			Query *query = get_view_query(view);
+
+			if (!info->inView)
+				info->dependencies = list_append_unique_oid(info->dependencies, relationId);
+
+			info->inView = true;
+			result = visitQuery(query, info);
+
+			heap_close(view, NoLock);
+		}
+
+	}
+	else if (rtekind == RTE_TABLEFUNC)
+	{
+		result = visitAllNodes((Node *) entry->tablefunc, info);
+	}
+	else if (rtekind == RTE_FUNCTION)
+	{
+		result = visitAllNodes((Node *) entry->functions, info);
+	}
+	else if (rtekind == RTE_SUBQUERY)
+	{
+		result = visitQuery(entry->subquery, info);
+	}
+
+	return result;
+}
+
+
+static bool
+visitQuery(Query *node, AssertionInfo *info)
+{
+	info->rtable = node->rtable;
+
+	if (info->inComparison)
+	{
+		int functions = functionsForTargetList(node->targetList);
+		Bitmapset *strategies = strategiesForOperators(info->operators);
+
+		if (CanOptimise(strategies))
+		{
+			RowCompareType rowCompareType = (RowCompareType) bms_first_member(strategies);
+			info->label = labelForComparisonWithAggFuncs(
+				info->label,
+				info->invert ? oppositeCompareType(rowCompareType) : rowCompareType,
+				functions
+			);
+		}
+		else
+		{
+			/*
+			 * Either no btree interpretation was found for the operator(s), there were
+			 * multiple interpretations that were incompatible with each other, or the
+			 * found interpretations were not able to be optimised. We must therefore
+			 * assume that both INSERT and DELETE operations may be invalidating.
+			 */
+			info->label = INSERT_DELETE;
+		}
+	}
+	else if (node->hasWindowFuncs)
+	{
+		info->label = INSERT_DELETE;
+	}
+
+	return query_tree_walker(node,
+							 visitAllNodes,
+							 info,
+							 QTW_IGNORE_RANGE_TABLE);
+}
+
+
+static bool
+visitSetOperationStmt(SetOperationStmt *node, AssertionInfo *info)
+{
+	info->setOp = node->op;
+
+	if (visitAllNodes(node->larg, info))
+		return true;
+
+	if (info->setOp == SETOP_EXCEPT)
+		info->label = oppositeDmlOp(info->label);
+
+	return visitAllNodes(node->rarg, info);
+}
+
+
+static bool
+visitBoolExpr(BoolExpr *node, AssertionInfo *info)
+{
+	if (node->boolop == NOT_EXPR)
+		info->label = oppositeDmlOp(info->label);
+
+	return expression_tree_walker((Node *) node, visitAllNodes, (void *) info);
+}
+
+
+// TODO refactor this function
+static bool
+visitSubLink(SubLink *node, AssertionInfo *info)
+{
+	List *operators;
+	bool  invert;
+	bool  inComparison;
+	bool  inExists;
+
+	switch (node->subLinkType)
+	{
+		case ARRAY_SUBLINK: // TODO write tests for this
+		case EXPR_SUBLINK:
+		{
+			Expr *expr = info->expr;
+			bool hasExpr = (expr != NULL);
+
+			if (hasExpr && IsA(expr, OpExpr))
+			{
+				OpExpr *opExpr = (OpExpr *) expr;
+				inComparison = true;
+				inExists = false;
+
+				/*
+				 * Optimisation code is written under the assumption that the sub-select is the
+				 * right operand. If it is the left operand the comparison needs to be inverted.
+				 */
+				invert = (list_nth_node(SubLink, opExpr->args, 0) == node);
+				operators = list_make1_oid(opExpr->opno);
+			}
+			else if (hasExpr && IsA(expr, FuncExpr) &&
+					((FuncExpr *)expr)->funcresulttype == BOOLOID)
+			{
+				/*
+				 * We are inside a function invocation that returns Boolean but is not an OpExpr.
+				 * Let's exploit the fact that "expr == TRUE -> expr", and pretend there is an
+				 * equality operator.
+				 */
+				inComparison = true;
+				inExists = false;
+				operators = list_make1_oid(F_BOOLEQ);
+				invert = false;
+			}
+			else if (exprType((const Node *) node) == BOOLOID)
+			{
+				/*
+				 * We are _not_ inside either an OpExpr or FuncExpr, but we are a query that can be
+				 * coerced to Boolean. We use the same logic above e.g. "expr == TRUE -> expr"
+				 */
+				inComparison = true;
+				inExists = false;
+				operators = list_make1_oid(F_BOOLEQ);
+				invert = false;
+			}
+			else
+			{
+				inComparison = false;
+				inExists = false;
+				invert = false;
+				operators = NIL;
+			}
+		}
+		break;
+
+		case ALL_SUBLINK:
+		case ANY_SUBLINK:
+		case ROWCOMPARE_SUBLINK:
+		{
+			if (IsA(node->testexpr, OpExpr))
+			{
+				OpExpr *expr = (OpExpr *) node->testexpr;
+				inComparison = true;
+				inExists = false;
+				invert = false;
+				operators = list_make1_oid(expr->opno);
+			}
+			else if (IsA(node->testexpr, RowCompareExpr))
+			{
+				RowCompareExpr *expr = (RowCompareExpr *) node->testexpr;
+				inComparison = true;
+				inExists = false;
+				invert = false;
+				operators = list_copy(expr->opnos);
+			}
+			else
+			{
+				inComparison = false;
+				inExists = false;
+				invert = false;
+				operators = NIL;
+			}
+		}
+		break;
+
+		case EXISTS_SUBLINK:
+		{
+			/* existential quantification, no operators */
+			inComparison = false;
+			inExists = true;
+			invert = false;
+			operators = NIL;
+		}
+		break;
+			// case MULTIEXPR_SUBLINK: // TODO write tests for MULTIEXPR_SUBLINK? -- or, can it only occur in UPDATEs?
+		default:
+		{
+			elog(ERROR, "unhandled sublink type %u", node->subLinkType);
+			return true;
+		}
+
+	}
+
+	info->operators = operators;
+	info->invert = invert;
+	info->inComparison = inComparison;
+	info->inExists = inExists;
+	info->setOp = SETOP_NONE;
+
+	return expression_tree_walker((Node *) node, visitAllNodes, (void *) info);
+}
+
+
+static bool
+visitTargetEntry(TargetEntry *node, AssertionInfo *info)
+{
+	info->inTargetEntry = true;
+	return expression_tree_walker((Node *) node, visitAllNodes, (void *) info);
+}
+
+
+static bool
+visitFromExpr(FromExpr *node, AssertionInfo *info)
+{
+	info->inExists = false;
+	info->inComparison = false;
+	return expression_tree_walker((Node *) node, visitAllNodes, (void *) info);
+}
+
+
+static bool
+visitFuncExpr(FuncExpr *node, AssertionInfo *info)
+{
+	Oid lang = get_func_lang(node->funcid);
+
+	info->expr = (Expr *) node;
+
+	if (!(lang == INTERNALlanguageId || lang == SQLlanguageId))
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_AMBIGUOUS_FUNCTION),
+				 errmsg("function \"%s\" uses unsupported language \"%s\"",
+				   get_func_name(node->funcid), get_language_name(lang, false))));
+		return true;
+	}
+
+	if (expression_tree_walker((Node *) node, visitAllNodes, (void *) info))
+		return true;
+
+	if (lang == SQLlanguageId)
+	{
+		Query *query = queryForSQLFunction(node);
+		Node *next;
+		if (node->funcretset)
+			next = (Node *) query;
+		else
+			next = (Node *) ((TargetEntry *) linitial(query->targetList))->expr;
+
+		return visitAllNodes(next, info);
+	}
+
+	return false;
+}
+
+
+static bool
+visitExpr(Expr *node, AssertionInfo *info)
+{
+	info->expr = node;
+	return expression_tree_walker((Node *) node, visitAllNodes, (void *) info);
+}
+
+
+static bool
+visitVar(Var *node, AssertionInfo *info)
+{
+	RangeTblEntry *entry = rt_fetch(node->varno, info->rtable);
+
+	// TODO we should do this only for Tables and not Views?
+	// TODO optimisations for set-operations
+	if (entry->rtekind == RTE_RELATION && !(info->inExists && info->setOp == SETOP_NONE))
+	{
+		Oid relationId = getrelid(node->varno, info->rtable);
+		ObjectAddress *column = (ObjectAddress *) palloc(sizeof(ObjectAddress));
+
+		column->classId = RelationRelationId;
+		column->objectId = relationId;
+		column->objectSubId = node->varattno;
+
+		if (!listContainsObjectAddress(info->columns, column))
+			info->columns = lcons(column, info->columns);
+
+		info->relations = list_append_unique_oid(info->relations, relationId);
+		info->updates = list_append_unique_oid(info->updates, relationId);
+	}
+
+	return expression_tree_walker((Node *) node, visitAllNodes, (void *) info);
+}
+
+
+static bool
+visitAllNodes(Node *node, AssertionInfo *info)
+{
+	AssertionInfo stored;
+	bool result;
+
+	copyAssertionInfo(&stored, info);
+
+	if (node == NULL)
+		result = false;
+	else if (IsA(node, RangeTblRef))
+		result = visitRangeTblRef((RangeTblRef *) node, info);
+	else if (IsA(node, Query))
+		result = visitQuery((Query *) node, info);
+	else if (IsA(node, BoolExpr))
+		result = visitBoolExpr((BoolExpr *) node, info);
+	else if (IsA(node, SubLink))
+		result = visitSubLink((SubLink *) node, info);
+	else if (IsA(node, SetOperationStmt))
+		result = visitSetOperationStmt((SetOperationStmt *) node, info);
+	else if (IsA(node, FuncExpr))
+		result = visitFuncExpr((FuncExpr *) node, info);
+	else if (IsA(node, OpExpr) ||
+			 IsA(node, DistinctExpr) ||
+			 IsA(node, NullIfExpr))
+		result = visitExpr((Expr *) node, info);
+	else if (IsA(node, TargetEntry))
+		result = visitTargetEntry((TargetEntry *) node, info);
+	else if (IsA(node, Var))
+		result = visitVar((Var *) node, info);
+	else if (IsA(node, FromExpr))
+		result = visitFromExpr((FromExpr *) node, info);
+	else
+		result = expression_tree_walker(node, visitAllNodes, (void *) info);
+
+	copyAssertionInfo(info, &stored);
+
+	return result;
+}
+
+
+static bool
+visitAggrefNodes(Node *node, int *aggFuncs)
+{
+	if (node == NULL)
+		return false;
+	else if (IsA(node, Aggref))
+		return visitAggref((Aggref *) node, aggFuncs);
+	else if(IsA(node, WindowFunc))
+		return visitWindowFunc((WindowFunc *) node, aggFuncs);
+	else
+		return expression_tree_walker(node, visitAggrefNodes, (void *) aggFuncs);
+}
+
+
+static bool
+visitAggref(Aggref *node, int *aggFuncs)
+{
+	*aggFuncs |= funcMaskForFuncOid(node->aggfnoid);
+	return expression_tree_walker((Node *) node, visitAggrefNodes, (void *) aggFuncs);
+}
+
+
+static bool
+visitWindowFunc(WindowFunc *node, int *aggFuncs)
+{
+	*aggFuncs |= funcMaskForFuncOid(node->winfnoid);
+
+	return expression_tree_walker((Node *) node, visitAggrefNodes, (void *) aggFuncs);
+}
+
+
+ObjectAddress
+CreateAssertion(CreateAssertionStmt *stmt)
+{
+	Oid namespaceId;
+	char *assertion_name;
+	AclResult aclresult;
+	Node *expr;
+	ParseState *pstate;
+	char *ccsrc;
+	char *ccbin;
+	Oid constrOid;
+	AssertionInfo info;
+	ListCell *lc;
+	ObjectAddress address;
+
+	namespaceId = QualifiedNameGetCreationNamespace(stmt->assertion_name,
+													&assertion_name);
+
+	aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(), ACL_CREATE);
+	if (aclresult != ACLCHECK_OK)
+		aclcheck_error(aclresult, ACL_KIND_NAMESPACE,
+					   get_namespace_name(namespaceId));
+
+	if (ConstraintNameIsUsed(CONSTRAINT_ASSERTION, InvalidOid, namespaceId, assertion_name))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_NAME),
+				 errmsg("assertion \"%s\" already exists", assertion_name)));
+
+	pstate = make_parsestate(NULL);
+	expr = transformExpr(pstate, stmt->constraint->raw_expr, EXPR_KIND_ASSERTION_CHECK);
+	expr = coerce_to_boolean(pstate, expr, "CHECK");
+
+	ccbin = nodeToString(expr);
+	ccsrc = deparse_expression(expr, NIL, false, false);
+
+	constrOid = CreateConstraintEntry(assertion_name,
+									  namespaceId,
+									  CONSTRAINT_CHECK, /* constraint type */
+									  stmt->constraint->deferrable,
+									  stmt->constraint->initdeferred,
+									  !stmt->constraint->skip_validation,
+									  InvalidOid, /* not a relation constraint */
+									  NULL,          /* no keys */
+									  0,          /* no keys */
+									  InvalidOid, /* not a domain constraint */
+									  InvalidOid, /* no associated index */
+									  InvalidOid, /* foreign key fields ... */
+									  NULL,
+									  NULL,
+									  NULL,
+									  NULL,
+									  0,
+									  ' ',
+									  ' ',
+									  ' ',
+									  NULL,    /* not an exclusion constraint */
+									  expr, /* tree form of check constraint */
+									  ccbin, /* binary form of check constraint */
+									  ccsrc, /* source form of check constraint */
+									  true, /* is local */
+									  0,   /* inhcount */
+									  false, /* noinherit XXX */
+									  false); /* is_internal */
+
+	initAssertionInfo(&info);
+	visitAllNodes(expr, &info);
+
+	foreach (lc, info.relations)
+	{
+		Oid relationId = lfirst_oid(lc);
+		CreateTrigStmt *trigger;
+		Relation rel;
+
+		rel = heap_open(relationId, ShareLock); // XXX
+
+		trigger = makeNode(CreateTrigStmt);
+		trigger->trigname = "AssertionTrigger";
+		trigger->relation = makeRangeVar(get_namespace_name(namespaceId),
+										 pstrdup(RelationGetRelationName(rel)),
+										 -1);
+		trigger->funcname = SystemFuncName("assertion_check");
+		trigger->args = NIL;
+		trigger->row = false;
+		trigger->timing = TRIGGER_TYPE_AFTER;
+		trigger->events = triggerOnEvents(&info, relationId);
+		trigger->columns = triggerOnColumns(&info, relationId);
+		trigger->whenClause = NULL;
+		trigger->isconstraint = true;
+		trigger->deferrable = stmt->constraint->deferrable;
+		trigger->initdeferred = stmt->constraint->initdeferred;
+		trigger->constrrel = NULL;
+
+		CreateTrigger(trigger, NULL, InvalidOid, relationId, constrOid, InvalidOid, true);
+
+		heap_close(rel, NoLock);
+	}
+
+	/*
+	 * Record dependencies between the constraint and the relations found in the
+	 * top-level expression. Dependencies to specific columns will already have
+	 * been recorded by the trigger creation.
+	 */
+	ObjectAddress myself, referenced;
+	ListCell *cell;
+
+	myself.classId = ConstraintRelationId;
+	myself.objectId = constrOid;
+	myself.objectSubId = 0;
+
+	foreach (cell, info.dependencies)
+	{
+		referenced.classId = RelationRelationId;
+		referenced.objectId = lfirst_oid(cell);
+		referenced.objectSubId = 0;
+		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+	}
+
+	test_assertion_expr(assertion_name, ccsrc);
+
+	ObjectAddressSet(address, ConstraintRelationId, constrOid);
+
+	return address;
+}
+
+
+ObjectAddress
+RenameAssertion(RenameStmt *stmt)
+{
+	Oid           assertionOid;
+	ObjectAddress address;
+	Relation      rel;
+	HeapTuple     tuple;
+	Form_pg_constraint con;
+	AclResult     aclresult;
+
+	List *oldName = castNode(List, stmt->object);
+	char *newName = stmt->newname;
+
+	rel = heap_open(ConstraintRelationId, RowExclusiveLock);
+	assertionOid = get_assertion_oid(oldName, false);
+
+	tuple = SearchSysCache1(CONSTROID, ObjectIdGetDatum(assertionOid));
+	if (!HeapTupleIsValid(tuple))
+		elog(ERROR, "cache lookup failed for constraint %u",
+			 assertionOid);
+	con = (Form_pg_constraint) GETSTRUCT(tuple);
+
+	/* must be owner */
+	if (!pg_constraint_ownercheck(assertionOid, GetUserId()))
+		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CONVERSION,
+					   NameListToString(oldName));
+
+	/* must have CREATE privilege on namespace */
+	aclresult = pg_namespace_aclcheck(con->connamespace, GetUserId(), ACL_CREATE);
+	if (aclresult != ACLCHECK_OK)
+		aclcheck_error(aclresult, ACL_KIND_NAMESPACE,
+					   get_namespace_name(con->connamespace));
+
+	ReleaseSysCache(tuple);
+	RenameConstraintById(assertionOid, newName);
+	ObjectAddressSet(address, ConstraintRelationId, assertionOid);
+	heap_close(rel, NoLock);
+
+	return address;
+}
diff --git a/src/backend/commands/event_trigger.c b/src/backend/commands/event_trigger.c
index 8455138ed3..085645007d 100644
--- a/src/backend/commands/event_trigger.c
+++ b/src/backend/commands/event_trigger.c
@@ -88,6 +88,7 @@ typedef enum
 static event_trigger_support_data event_trigger_support[] = {
 	{"ACCESS METHOD", true},
 	{"AGGREGATE", true},
+	{"ASSERTION", true},
 	{"CAST", true},
 	{"CONSTRAINT", true},
 	{"COLLATION", true},
@@ -1081,6 +1082,7 @@ EventTriggerSupportsObjectType(ObjectType obtype)
 			return false;
 		case OBJECT_ACCESS_METHOD:
 		case OBJECT_AGGREGATE:
+		case OBJECT_ASSERTION:
 		case OBJECT_AMOP:
 		case OBJECT_AMPROC:
 		case OBJECT_ATTRIBUTE:
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index ddbbc79823..0543995939 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -4304,6 +4304,17 @@ _copyCreateSchemaStmt(const CreateSchemaStmt *from)
 	return newnode;
 }
 
+static CreateAssertionStmt *
+_copyCreateAssertionStmt(const CreateAssertionStmt *from)
+{
+	CreateAssertionStmt *newnode = makeNode(CreateAssertionStmt);
+
+	COPY_NODE_FIELD(assertion_name);
+	COPY_NODE_FIELD(constraint);
+
+	return newnode;
+}
+
 static CreateConversionStmt *
 _copyCreateConversionStmt(const CreateConversionStmt *from)
 {
@@ -5373,6 +5384,9 @@ copyObjectImpl(const void *from)
 		case T_CreateSchemaStmt:
 			retval = _copyCreateSchemaStmt(from);
 			break;
+		case T_CreateAssertionStmt:
+			retval = _copyCreateAssertionStmt(from);
+			break;
 		case T_CreateConversionStmt:
 			retval = _copyCreateConversionStmt(from);
 			break;
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 30ccc9c5ae..42323dac89 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -2117,6 +2117,15 @@ _equalCreateSchemaStmt(const CreateSchemaStmt *a, const CreateSchemaStmt *b)
 	return true;
 }
 
+static bool
+_equalCreateAssertionStmt(const CreateAssertionStmt *a, const CreateAssertionStmt *b)
+{
+	COMPARE_NODE_FIELD(assertion_name);
+	COMPARE_NODE_FIELD(constraint);
+
+	return true;
+}
+
 static bool
 _equalCreateConversionStmt(const CreateConversionStmt *a, const CreateConversionStmt *b)
 {
@@ -3511,6 +3520,9 @@ equal(const void *a, const void *b)
 		case T_CreateSchemaStmt:
 			retval = _equalCreateSchemaStmt(a, b);
 			break;
+		case T_CreateAssertionStmt:
+			retval = _equalCreateAssertionStmt(a, b);
+			break;
 		case T_CreateConversionStmt:
 			retval = _equalCreateConversionStmt(a, b);
 			break;
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index e42b7caff6..89fdbb1793 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -259,11 +259,11 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 		CreateOpFamilyStmt AlterOpFamilyStmt CreatePLangStmt
 		CreateSchemaStmt CreateSeqStmt CreateStmt CreateStatsStmt CreateTableSpaceStmt
 		CreateFdwStmt CreateForeignServerStmt CreateForeignTableStmt
-		CreateAssertStmt CreateTransformStmt CreateTrigStmt CreateEventTrigStmt
+		CreateAssertionStmt CreateTransformStmt CreateTrigStmt CreateEventTrigStmt
 		CreateUserStmt CreateUserMappingStmt CreateRoleStmt CreatePolicyStmt
 		CreatedbStmt DeclareCursorStmt DefineStmt DeleteStmt DiscardStmt DoStmt
 		DropOpClassStmt DropOpFamilyStmt DropPLangStmt DropStmt
-		DropAssertStmt DropCastStmt DropRoleStmt
+		DropCastStmt DropRoleStmt
 		DropdbStmt DropTableSpaceStmt
 		DropTransformStmt
 		DropUserMappingStmt ExplainStmt FetchStmt
@@ -854,7 +854,7 @@ stmt :
 			| CopyStmt
 			| CreateAmStmt
 			| CreateAsStmt
-			| CreateAssertStmt
+			| CreateAssertionStmt
 			| CreateCastStmt
 			| CreateConversionStmt
 			| CreateDomainStmt
@@ -890,7 +890,6 @@ stmt :
 			| DeleteStmt
 			| DiscardStmt
 			| DoStmt
-			| DropAssertStmt
 			| DropCastStmt
 			| DropOpClassStmt
 			| DropOpFamilyStmt
@@ -5591,45 +5590,28 @@ enable_trigger:
  *
  *		QUERIES :
  *				CREATE ASSERTION ...
- *				DROP ASSERTION ...
  *
  *****************************************************************************/
 
-CreateAssertStmt:
-			CREATE ASSERTION name CHECK '(' a_expr ')'
+CreateAssertionStmt:
+			CREATE ASSERTION any_name CHECK '(' a_expr ')'
 			ConstraintAttributeSpec
 				{
-					CreateTrigStmt *n = makeNode(CreateTrigStmt);
-					n->trigname = $3;
-					n->args = list_make1($6);
-					n->isconstraint  = true;
-					processCASbits($8, @8, "ASSERTION",
-								   &n->deferrable, &n->initdeferred, NULL,
-								   NULL, yyscanner);
-
-					ereport(ERROR,
-							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-							 errmsg("CREATE ASSERTION is not yet implemented")));
-
-					$$ = (Node *)n;
-				}
-		;
-
-DropAssertStmt:
-			DROP ASSERTION name opt_drop_behavior
-				{
-					DropStmt *n = makeNode(DropStmt);
-					n->objects = NIL;
-					n->behavior = $4;
-					n->removeType = OBJECT_TRIGGER; /* XXX */
-					ereport(ERROR,
-							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-							 errmsg("DROP ASSERTION is not yet implemented")));
-					$$ = (Node *) n;
+					CreateAssertionStmt *n = makeNode(CreateAssertionStmt);
+					Constraint *c = makeNode(Constraint);
+					c->contype = CONSTR_CHECK;
+					c->location = @4;
+					c->raw_expr = $6;
+					c->cooked_expr = NULL;
+ 					processCASbits($8, @8, "ASSERTION",
+								   &c->deferrable, &c->initdeferred, NULL,
+ 								   NULL, yyscanner);
+					n->assertion_name = $3;
+					n->constraint = c;
+ 					$$ = (Node *)n;
 				}
 		;
 
-
 /*****************************************************************************
  *
  *		QUERY :
@@ -6283,6 +6265,7 @@ drop_type_any_name:
 			| MATERIALIZED VIEW						{ $$ = OBJECT_MATVIEW; }
 			| INDEX									{ $$ = OBJECT_INDEX; }
 			| FOREIGN TABLE							{ $$ = OBJECT_FOREIGN_TABLE; }
+			| ASSERTION								{ $$ = OBJECT_ASSERTION; }
 			| COLLATION								{ $$ = OBJECT_COLLATION; }
 			| CONVERSION_P							{ $$ = OBJECT_CONVERSION; }
 			| STATISTICS							{ $$ = OBJECT_STATISTIC_EXT; }
@@ -6552,6 +6535,7 @@ comment_type_any_name:
 			| TABLE								{ $$ = OBJECT_TABLE; }
 			| VIEW								{ $$ = OBJECT_VIEW; }
 			| MATERIALIZED VIEW					{ $$ = OBJECT_MATVIEW; }
+			| ASSERTION							{ $$ = OBJECT_ASSERTION; }
 			| COLLATION							{ $$ = OBJECT_COLLATION; }
 			| CONVERSION_P						{ $$ = OBJECT_CONVERSION; }
 			| FOREIGN TABLE						{ $$ = OBJECT_FOREIGN_TABLE; }
@@ -8402,6 +8386,15 @@ RenameStmt: ALTER AGGREGATE aggregate_with_argtypes RENAME TO name
 					n->missing_ok = false;
 					$$ = (Node *)n;
 				}
+			| ALTER ASSERTION any_name RENAME TO name
+				{
+					RenameStmt *n = makeNode(RenameStmt);
+					n->renameType = OBJECT_ASSERTION;
+					n->object = (Node *) $3;
+					n->newname = $6;
+					n->missing_ok = false;
+					$$ = (Node *)n;
+				}
 			| ALTER COLLATION any_name RENAME TO name
 				{
 					RenameStmt *n = makeNode(RenameStmt);
@@ -8986,6 +8979,15 @@ AlterObjectSchemaStmt:
 					n->missing_ok = false;
 					$$ = (Node *)n;
 				}
+			| ALTER ASSERTION any_name SET SCHEMA name
+				{
+					AlterObjectSchemaStmt *n = makeNode(AlterObjectSchemaStmt);
+					n->objectType = OBJECT_ASSERTION;
+					n->object = (Node *) $3;
+					n->newschema = $6;
+					n->missing_ok = false;
+					$$ = (Node *)n;
+				}
 			| ALTER COLLATION any_name SET SCHEMA name
 				{
 					AlterObjectSchemaStmt *n = makeNode(AlterObjectSchemaStmt);
@@ -9271,6 +9273,14 @@ AlterOwnerStmt: ALTER AGGREGATE aggregate_with_argtypes OWNER TO RoleSpec
 					n->newowner = $6;
 					$$ = (Node *)n;
 				}
+			| ALTER ASSERTION any_name OWNER TO RoleSpec
+				{
+					AlterOwnerStmt *n = makeNode(AlterOwnerStmt);
+					n->objectType = OBJECT_ASSERTION;
+					n->object = (Node *) $3;
+					n->newowner = $6;
+					$$ = (Node *)n;
+				}
 			| ALTER COLLATION any_name OWNER TO RoleSpec
 				{
 					AlterOwnerStmt *n = makeNode(AlterOwnerStmt);
diff --git a/src/backend/parser/parse_agg.c b/src/backend/parser/parse_agg.c
index 6a9f1b0217..08d233ba3a 100644
--- a/src/backend/parser/parse_agg.c
+++ b/src/backend/parser/parse_agg.c
@@ -450,6 +450,7 @@ check_agglevels_and_constraints(ParseState *pstate, Node *expr)
 			break;
 		case EXPR_KIND_CHECK_CONSTRAINT:
 		case EXPR_KIND_DOMAIN_CHECK:
+		case EXPR_KIND_ASSERTION_CHECK:
 			if (isAgg)
 				err = _("aggregate functions are not allowed in check constraints");
 			else
@@ -867,6 +868,7 @@ transformWindowFuncCall(ParseState *pstate, WindowFunc *wfunc,
 			break;
 		case EXPR_KIND_CHECK_CONSTRAINT:
 		case EXPR_KIND_DOMAIN_CHECK:
+		case EXPR_KIND_ASSERTION_CHECK:
 			err = _("window functions are not allowed in check constraints");
 			break;
 		case EXPR_KIND_COLUMN_DEFAULT:
diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index b2f5e46e3b..a8ada122ac 100644
--- a/src/backend/parser/parse_expr.c
+++ b/src/backend/parser/parse_expr.c
@@ -1817,6 +1817,7 @@ transformSubLink(ParseState *pstate, SubLink *sublink)
 		case EXPR_KIND_RETURNING:
 		case EXPR_KIND_VALUES:
 		case EXPR_KIND_VALUES_SINGLE:
+		case EXPR_KIND_ASSERTION_CHECK:
 		case EXPR_KIND_CALL:
 			/* okay */
 			break;
@@ -3452,6 +3453,7 @@ ParseExprKindName(ParseExprKind exprKind)
 			return "VALUES";
 		case EXPR_KIND_CHECK_CONSTRAINT:
 		case EXPR_KIND_DOMAIN_CHECK:
+		case EXPR_KIND_ASSERTION_CHECK:
 			return "CHECK";
 		case EXPR_KIND_COLUMN_DEFAULT:
 		case EXPR_KIND_FUNCTION_DEFAULT:
diff --git a/src/backend/parser/parse_func.c b/src/backend/parser/parse_func.c
index ffae0f3cf3..9acf54b383 100644
--- a/src/backend/parser/parse_func.c
+++ b/src/backend/parser/parse_func.c
@@ -2263,6 +2263,10 @@ check_srf_call_placement(ParseState *pstate, Node *last_srf, int location)
 			/* okay, since we process this like a SELECT tlist */
 			pstate->p_hasTargetSRFs = true;
 			break;
+		case EXPR_KIND_ASSERTION_CHECK:
+			/* okay */
+			pstate->p_hasTargetSRFs = true;
+			break;
 		case EXPR_KIND_CHECK_CONSTRAINT:
 		case EXPR_KIND_DOMAIN_CHECK:
 			err = _("set-returning functions are not allowed in check constraints");
diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c
index ec98a612ec..fee335502c 100644
--- a/src/backend/tcop/utility.c
+++ b/src/backend/tcop/utility.c
@@ -29,6 +29,7 @@
 #include "commands/cluster.h"
 #include "commands/comment.h"
 #include "commands/collationcmds.h"
+#include "commands/constraint.h"
 #include "commands/conversioncmds.h"
 #include "commands/copy.h"
 #include "commands/createas.h"
@@ -159,6 +160,7 @@ check_xact_readonly(Node *parsetree)
 		case T_RenameStmt:
 		case T_CommentStmt:
 		case T_DefineStmt:
+		case T_CreateAssertionStmt:
 		case T_CreateCastStmt:
 		case T_CreateEventTrigStmt:
 		case T_AlterEventTrigStmt:
@@ -1493,6 +1495,10 @@ ProcessUtilitySlow(ParseState *pstate,
 				address = DefineDomain((CreateDomainStmt *) parsetree);
 				break;
 
+			case T_CreateAssertionStmt:
+				address = CreateAssertion((CreateAssertionStmt *) parsetree);
+				break;
+
 			case T_CreateConversionStmt:
 				address = CreateConversionCommand((CreateConversionStmt *) parsetree);
 				break;
@@ -1903,6 +1909,9 @@ AlterObjectTypeCommandTag(ObjectType objtype)
 		case OBJECT_AGGREGATE:
 			tag = "ALTER AGGREGATE";
 			break;
+		case OBJECT_ASSERTION:
+			tag = "ALTER ASSERTION";
+			break;
 		case OBJECT_ATTRIBUTE:
 			tag = "ALTER TYPE";
 			break;
@@ -2241,6 +2250,9 @@ CreateCommandTag(Node *parsetree)
 				case OBJECT_DOMAIN:
 					tag = "DROP DOMAIN";
 					break;
+				case OBJECT_ASSERTION:
+					tag = "DROP ASSERTION";
+					break;
 				case OBJECT_COLLATION:
 					tag = "DROP COLLATION";
 					break;
@@ -2671,6 +2683,10 @@ CreateCommandTag(Node *parsetree)
 			tag = "REINDEX";
 			break;
 
+		case T_CreateAssertionStmt:
+			tag = "CREATE ASSERTION";
+			break;
+
 		case T_CreateConversionStmt:
 			tag = "CREATE CONVERSION";
 			break;
@@ -3271,6 +3287,10 @@ GetCommandLogLevel(Node *parsetree)
 			lev = LOGSTMT_ALL;	/* should this be DDL? */
 			break;
 
+		case T_CreateAssertionStmt:
+			lev = LOGSTMT_DDL;
+			break;
+
 		case T_CreateConversionStmt:
 			lev = LOGSTMT_DDL;
 			break;
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index e8aa179347..dbbe1a5513 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -1557,6 +1557,25 @@ get_func_retset(Oid funcid)
 	return result;
 }
 
+/*
+ * get_func_lang
+ *		Given procedure id, return the function's language id.
+ */
+Oid
+get_func_lang(Oid funcid)
+{
+	HeapTuple	tp;
+	Oid			result;
+
+	tp = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
+	if (!HeapTupleIsValid(tp))
+		elog(ERROR, "cache lookup failed for function %u", funcid);
+
+	result = ((Form_pg_proc) GETSTRUCT(tp))->prolang;
+	ReleaseSysCache(tp);
+	return result;
+}
+
 /*
  * func_strict
  *		Given procedure id, return the function's proisstrict flag.
diff --git a/src/bin/psql/command.c b/src/bin/psql/command.c
index 015c391aa4..928e280090 100644
--- a/src/bin/psql/command.c
+++ b/src/bin/psql/command.c
@@ -785,6 +785,9 @@ exec_command_d(PsqlScanState scan_state, bool active_branch, const char *cmd)
 			case 'p':
 				success = permissionsList(pattern);
 				break;
+			case 'Q':
+				success = describeAssertions(pattern);
+				break;
 			case 'T':
 				success = describeTypes(pattern, show_verbose, show_system);
 				break;
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index d2787ab41b..41ebc2ce13 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -132,6 +132,66 @@ describeAggregates(const char *pattern, bool verbose, bool showSystem)
 	return true;
 }
 
+/* \dA
+ * Takes an optional regexp to select particular assertions
+ */
+bool
+describeAssertions(const char *pattern)
+{
+	PQExpBufferData buf;
+	PGresult   *res;
+	printQueryOpt myopt = pset.popt;
+
+	if (pset.sversion < 90400)
+	{
+		fprintf(stderr, _("The server (version %d.%d) does not support assertions.\n"),
+				pset.sversion / 10000, (pset.sversion / 100) % 100);
+		return true;
+	}
+
+	initPQExpBuffer(&buf);
+
+	printfPQExpBuffer(&buf,
+					  "SELECT n.nspname AS \"%s\",\n"
+							  "  c.conname AS \"%s\",\n"
+							  "  pg_catalog.pg_get_constraintdef(c.oid, true) AS \"%s\",\n"
+							  "  pg_catalog.obj_description(c.oid, 'pg_constraint') AS \"%s\"\n"
+							  "FROM pg_catalog.pg_constraint c\n"
+							  "     LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.connamespace\n"
+							  "WHERE c.conrelid = 0 AND c.contypid = 0\n",
+					  gettext_noop("Schema"),
+					  gettext_noop("Name"),
+					  gettext_noop("Definition"),
+					  gettext_noop("Description"));
+
+	if (!pattern)
+		appendPQExpBuffer(&buf, "      AND n.nspname <> 'pg_catalog'\n"
+				"      AND n.nspname <> 'information_schema'\n");
+
+#if TODO
+	processSQLNamePattern(pset.db, &buf, pattern, true, false,
+						  "n.nspname", "c.conname", NULL,
+						  "pg_catalog.pg_constraint_is_visible(c.oid)");
+#endif
+
+	appendPQExpBuffer(&buf, "ORDER BY 1, 2, 3, 4;");
+
+	res = PSQLexec(buf.data);
+	termPQExpBuffer(&buf);
+	if (!res)
+		return false;
+
+	myopt.nullPrint = NULL;
+	myopt.title = _("List of assertions");
+	myopt.translate_header = true;
+
+	printQuery(res, &myopt, pset.queryFout, false, pset.logfile);
+
+	PQclear(res);
+	return true;
+}
+
+
 /*
  * \dA
  * Takes an optional regexp to select particular access methods
@@ -2475,6 +2535,38 @@ describeOneTableDetails(const char *schemaname,
 			PQclear(result);
 		}
 
+		/* print assertions referencing this table (none if no triggers) */
+		if (tableinfo.hastriggers)
+		{
+			printfPQExpBuffer(&buf,
+							  "SELECT conname,\n"
+									  "  pg_catalog.pg_get_constraintdef(c.oid, true) AS condef\n"
+									  "FROM pg_catalog.pg_constraint c\n"
+									  "WHERE c.oid IN (SELECT objid FROM pg_depend WHERE classid = 'pg_constraint'::pg_catalog.regclass AND refclassid = 'pg_class'::pg_catalog.regclass AND refobjid = '%s')\n"
+									  "  AND c.conrelid = 0 AND c.contypid = 0 AND c.contype = 'c'\n"
+									  "ORDER BY 1",
+							  oid);
+			result = PSQLexec(buf.data);
+			if (!result)
+				goto error_return;
+			else
+				tuples = PQntuples(result);
+
+			if (tuples > 0)
+			{
+				printTableAddFooter(&cont, _("Assertions:"));
+				for (i = 0; i < tuples; i++)
+				{
+					printfPQExpBuffer(&buf, "    \"%s\" %s",
+									  PQgetvalue(result, i, 0),
+									  PQgetvalue(result, i, 1));
+
+					printTableAddFooter(&cont, buf.data);
+				}
+			}
+			PQclear(result);
+		}
+
 		/* print rules */
 		if (tableinfo.hasrules && tableinfo.relkind != RELKIND_MATVIEW)
 		{
diff --git a/src/bin/psql/describe.h b/src/bin/psql/describe.h
index a4cc5efae0..7b405b65da 100644
--- a/src/bin/psql/describe.h
+++ b/src/bin/psql/describe.h
@@ -15,6 +15,9 @@ extern bool describeAggregates(const char *pattern, bool verbose, bool showSyste
 /* \dA */
 extern bool describeAccessMethods(const char *pattern, bool verbose);
 
+/* \dQ */
+extern bool describeAssertions(const char *pattern);
+
 /* \db */
 extern bool describeTablespaces(const char *pattern, bool verbose);
 
diff --git a/src/bin/psql/help.c b/src/bin/psql/help.c
index 702e742af4..9deabd195f 100644
--- a/src/bin/psql/help.c
+++ b/src/bin/psql/help.c
@@ -223,6 +223,7 @@ slashUsage(unsigned short int pager)
 	fprintf(output, _("  \\d[S+]                 list tables, views, and sequences\n"));
 	fprintf(output, _("  \\d[S+]  NAME           describe table, view, sequence, or index\n"));
 	fprintf(output, _("  \\da[S]  [PATTERN]      list aggregates\n"));
+	fprintf(output, _("  \\dQ     [PATTERN]      list assertions\n"));
 	fprintf(output, _("  \\dA[+]  [PATTERN]      list access methods\n"));
 	fprintf(output, _("  \\db[+]  [PATTERN]      list tablespaces\n"));
 	fprintf(output, _("  \\dc[S+] [PATTERN]      list conversions\n"));
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index b51098deca..7628ecb816 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -360,6 +360,22 @@ static const SchemaQuery Query_for_list_of_aggregates = {
 	NULL
 };
 
+static const SchemaQuery Query_for_list_of_assertions = {
+    /* catname */
+	"pg_catalog.pg_constraint c",
+	/* selcondition */
+	"(c.conrelid = 0 AND c.contypid = 0)",
+	/* viscondition */
+	"TRUE", //TODO: "pg_catalog.pg_constraint_is_visible(c.oid)",
+	/* namespace */
+	"c.connamespace",
+	/* result */
+	"pg_catalog.quote_ident(c.conname)",
+	/* qualresult */
+	NULL
+};
+
+
 static const SchemaQuery Query_for_list_of_datatypes = {
 	/* catname */
 	"pg_catalog.pg_type t",
@@ -1033,6 +1049,7 @@ typedef struct
 static const pgsql_thing_t words_after_create[] = {
 	{"ACCESS METHOD", NULL, NULL, THING_NO_ALTER},
 	{"AGGREGATE", NULL, &Query_for_list_of_aggregates},
+	{"ASSERTION", NULL, &Query_for_list_of_assertions},
 	{"CAST", NULL, NULL},		/* Casts have complex structures for names, so
 								 * skip it */
 	{"COLLATION", "SELECT pg_catalog.quote_ident(collname) FROM pg_catalog.pg_collation WHERE collencoding IN (-1, pg_catalog.pg_char_to_encoding(pg_catalog.getdatabaseencoding())) AND substring(pg_catalog.quote_ident(collname),1,%d)='%s'"},
@@ -1456,7 +1473,7 @@ psql_completion(const char *text, int start, int end)
 		"\\a",
 		"\\connect", "\\conninfo", "\\C", "\\cd", "\\copy",
 		"\\copyright", "\\crosstabview",
-		"\\d", "\\da", "\\dA", "\\db", "\\dc", "\\dC", "\\dd", "\\ddp", "\\dD",
+		"\\d", "\\da", "\\dA", "\\dQ", "\\db", "\\dc", "\\dC", "\\dd", "\\ddp", "\\dD",
 		"\\des", "\\det", "\\deu", "\\dew", "\\dE", "\\df",
 		"\\dF", "\\dFd", "\\dFp", "\\dFt", "\\dg", "\\di", "\\dl", "\\dL",
 		"\\dm", "\\dn", "\\do", "\\dO", "\\dp",
@@ -1607,6 +1624,11 @@ psql_completion(const char *text, int start, int end)
 	else if (Matches3("ALTER", "SCHEMA", MatchAny))
 		COMPLETE_WITH_LIST2("OWNER TO", "RENAME TO");
 
+	// TODO ASSERTION
+
+	else if (Matches3("ALTER", "ASSERTION", MatchAny))
+		COMPLETE_WITH_CONST("RENAME TO ");
+
 	/* ALTER COLLATION <name> */
 	else if (Matches3("ALTER", "COLLATION", MatchAny))
 		COMPLETE_WITH_LIST3("OWNER TO", "RENAME TO", "SET SCHEMA");
@@ -2720,7 +2742,7 @@ psql_completion(const char *text, int start, int end)
 /* DROP */
 	/* Complete DROP object with CASCADE / RESTRICT */
 	else if (Matches3("DROP",
-					  "COLLATION|CONVERSION|DOMAIN|EXTENSION|LANGUAGE|PUBLICATION|SCHEMA|SEQUENCE|SERVER|SUBSCRIPTION|STATISTICS|TABLE|TYPE|VIEW",
+					  "ASSERTION|COLLATION|CONVERSION|DOMAIN|EXTENSION|LANGUAGE|PUBLICATION|SCHEMA|SEQUENCE|SERVER|SUBSCRIPTION|STATISTICS|TABLE|TYPE|VIEW",
 					  MatchAny) ||
 			 Matches4("DROP", "ACCESS", "METHOD", MatchAny) ||
 			 (Matches4("DROP", "AGGREGATE|FUNCTION|PROCEDURE|ROUTINE", MatchAny, MatchAny) &&
@@ -3452,6 +3474,8 @@ psql_completion(const char *text, int start, int end)
 	}
 	else if (TailMatchesCS1("\\da*"))
 		COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_aggregates, NULL);
+	else if (TailMatchesCS1("\\dQ*"))
+		COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_assertions, NULL);
 	else if (TailMatchesCS1("\\dA*"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_access_methods);
 	else if (TailMatchesCS1("\\db*"))
diff --git a/src/include/catalog/namespace.h b/src/include/catalog/namespace.h
index 5f8cf4992e..841be6db59 100644
--- a/src/include/catalog/namespace.h
+++ b/src/include/catalog/namespace.h
@@ -140,6 +140,7 @@ extern bool OverrideSearchPathMatchesCurrent(OverrideSearchPath *path);
 extern void PushOverrideSearchPath(OverrideSearchPath *newpath);
 extern void PopOverrideSearchPath(void);
 
+extern Oid	get_assertion_oid(List *name, bool missing_ok);
 extern Oid	get_collation_oid(List *collname, bool missing_ok);
 extern Oid	get_conversion_oid(List *conname, bool missing_ok);
 extern Oid	FindDefaultConversionProc(int32 for_encoding, int32 to_encoding);
diff --git a/src/include/catalog/pg_constraint.h b/src/include/catalog/pg_constraint.h
index 8fca86d71e..060e436fcd 100644
--- a/src/include/catalog/pg_constraint.h
+++ b/src/include/catalog/pg_constraint.h
@@ -57,8 +57,7 @@ CATALOG(pg_constraint,2606)
 	 * contypid links to the pg_type row for a domain if this is a domain
 	 * constraint.  Otherwise it's 0.
 	 *
-	 * For SQL-style global ASSERTIONs, both conrelid and contypid would be
-	 * zero. This is not presently supported, however.
+	 * For SQL-style global ASSERTIONs, both conrelid and contypid are zero.
 	 */
 	Oid			contypid;		/* domain this constraint constrains */
 
diff --git a/src/include/catalog/pg_constraint_fn.h b/src/include/catalog/pg_constraint_fn.h
index 6bb1b09714..b5f06339fa 100644
--- a/src/include/catalog/pg_constraint_fn.h
+++ b/src/include/catalog/pg_constraint_fn.h
@@ -24,7 +24,7 @@ typedef enum ConstraintCategory
 {
 	CONSTRAINT_RELATION,
 	CONSTRAINT_DOMAIN,
-	CONSTRAINT_ASSERTION		/* for future expansion */
+	CONSTRAINT_ASSERTION
 } ConstraintCategory;
 
 extern Oid CreateConstraintEntry(const char *constraintName,
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 298e0ae2f0..d3e761e4d7 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -2081,6 +2081,10 @@ DESCR("oid of replica identity index if any");
 DATA(insert OID = 1250 (  unique_key_recheck	PGNSP PGUID 12 1 0 0 0 f f f f t f v s 0 0 2279 "" _null_ _null_ _null_ _null_ _null_ unique_key_recheck _null_ _null_ _null_ ));
 DESCR("deferred UNIQUE constraint check");
 
+DATA(insert OID = 3556 (  assertion_check	    PGNSP PGUID 12 1 0 0 0 f f f f t f v s 0 0 2279 "" _null_ _null_ _null_ _null_ _null_ assertion_check _null_ _null_ _null_ ));
+DESCR("assertion check");
+
+
 /* Generic referential integrity constraint triggers */
 DATA(insert OID = 1644 (  RI_FKey_check_ins		PGNSP PGUID 12 1 0 0 0 f f f f t f v s 0 0 2279 "" _null_ _null_ _null_ _null_ _null_ RI_FKey_check_ins _null_ _null_ _null_ ));
 DESCR("referential integrity FOREIGN KEY ... REFERENCES");
diff --git a/src/include/commands/constraint.h b/src/include/commands/constraint.h
new file mode 100644
index 0000000000..98aa8f996e
--- /dev/null
+++ b/src/include/commands/constraint.h
@@ -0,0 +1,10 @@
+#ifndef CONSTRAINT_H
+#define CONSTRAINT_H
+
+#include "catalog/objectaddress.h"
+#include "nodes/parsenodes.h"
+
+extern ObjectAddress CreateAssertion(CreateAssertionStmt *stmt);
+extern ObjectAddress RenameAssertion(RenameStmt *stmt);
+
+#endif
\ No newline at end of file
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index 2eb3d6d371..b4258aa483 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -414,6 +414,7 @@ typedef enum NodeTag
 	T_DropSubscriptionStmt,
 	T_CreateStatsStmt,
 	T_AlterCollationStmt,
+	T_CreateAssertionStmt,
 	T_CallStmt,
 
 	/*
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index b72178efd1..7103013d0c 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1618,6 +1618,7 @@ typedef enum ObjectType
 	OBJECT_AGGREGATE,
 	OBJECT_AMOP,
 	OBJECT_AMPROC,
+	OBJECT_ASSERTION,
 	OBJECT_ATTRIBUTE,			/* type's attribute, when distinct from column */
 	OBJECT_CAST,
 	OBJECT_COLUMN,
@@ -3271,6 +3272,16 @@ typedef struct ReindexStmt
 	int			options;		/* Reindex options flags */
 } ReindexStmt;
 
+/* ----------------------
+ *      CREATE ASSERTION Statement
+ */
+typedef struct CreateAssertionStmt
+{
+	NodeTag		type;
+	List    	*assertion_name;
+	Constraint	*constraint;
+} CreateAssertionStmt;
+
 /* ----------------------
  *		CREATE CONVERSION Statement
  * ----------------------
diff --git a/src/include/parser/parse_node.h b/src/include/parser/parse_node.h
index 4e96fa7907..68770aa3e0 100644
--- a/src/include/parser/parse_node.h
+++ b/src/include/parser/parse_node.h
@@ -59,6 +59,7 @@ typedef enum ParseExprKind
 	EXPR_KIND_VALUES_SINGLE,	/* single-row VALUES (in INSERT only) */
 	EXPR_KIND_CHECK_CONSTRAINT, /* CHECK constraint for a table */
 	EXPR_KIND_DOMAIN_CHECK,		/* CHECK constraint for a domain */
+	EXPR_KIND_ASSERTION_CHECK,	/* CHECK constraint for an assertion */
 	EXPR_KIND_COLUMN_DEFAULT,	/* default value for a table column */
 	EXPR_KIND_FUNCTION_DEFAULT, /* default parameter value for function */
 	EXPR_KIND_INDEX_EXPRESSION, /* index expression */
diff --git a/src/include/utils/acl.h b/src/include/utils/acl.h
index 67c7b2d4ac..82fe96075a 100644
--- a/src/include/utils/acl.h
+++ b/src/include/utils/acl.h
@@ -199,6 +199,7 @@ typedef enum AclObjectKind
 	ACL_KIND_OPCLASS,			/* pg_opclass */
 	ACL_KIND_OPFAMILY,			/* pg_opfamily */
 	ACL_KIND_COLLATION,			/* pg_collation */
+	ACL_KIND_CONSTRAINT,        /* pg_constraint */
 	ACL_KIND_CONVERSION,		/* pg_conversion */
 	ACL_KIND_STATISTICS,		/* pg_statistic_ext */
 	ACL_KIND_TABLESPACE,		/* pg_tablespace */
@@ -326,6 +327,7 @@ extern bool pg_opclass_ownercheck(Oid opc_oid, Oid roleid);
 extern bool pg_opfamily_ownercheck(Oid opf_oid, Oid roleid);
 extern bool pg_database_ownercheck(Oid db_oid, Oid roleid);
 extern bool pg_collation_ownercheck(Oid coll_oid, Oid roleid);
+extern bool pg_constraint_ownercheck(Oid constr_oid, Oid roleid);
 extern bool pg_conversion_ownercheck(Oid conv_oid, Oid roleid);
 extern bool pg_ts_dict_ownercheck(Oid dict_oid, Oid roleid);
 extern bool pg_ts_config_ownercheck(Oid cfg_oid, Oid roleid);
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index 9731e6f7ae..9709759dfd 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -115,6 +115,7 @@ extern int	get_func_nargs(Oid funcid);
 extern Oid	get_func_signature(Oid funcid, Oid **argtypes, int *nargs);
 extern Oid	get_func_variadictype(Oid funcid);
 extern bool get_func_retset(Oid funcid);
+extern Oid  get_func_lang(Oid funcid);
 extern bool func_strict(Oid funcid);
 extern char func_volatile(Oid funcid);
 extern char func_parallel(Oid funcid);
diff --git a/src/test/regress/expected/assertions.out b/src/test/regress/expected/assertions.out
new file mode 100644
index 0000000000..7fc0d710a3
--- /dev/null
+++ b/src/test/regress/expected/assertions.out
@@ -0,0 +1,779 @@
+BEGIN TRANSACTION;
+--
+-- Create some helper views and functions to allow us to more easily
+-- assert which operations will cause an assertion to be checked.
+--
+CREATE OR REPLACE VIEW invalidating_operation
+  (assertion_name,
+   relation_name,
+   operation)
+AS
+SELECT c.conname,
+       cl.relname,
+       v.operation
+  FROM pg_trigger t
+  JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+  JOIN pg_proc p ON (t.tgfoid = p.oid)
+  JOIN pg_class cl ON (t.tgrelid = cl.oid)
+  JOIN (VALUES ('INSERT', 1<<2),
+               ('DELETE', 1<<3|1<<5),
+               ('UPDATE', 1<<4))
+    AS v(operation, mask) ON ((v.mask & tgtype) > 0)
+ WHERE t.tgisinternal
+   AND p.proname = 'assertion_check';
+CREATE OR REPLACE VIEW invalidating_by_update_of_column
+  (assertion_name,
+   relation_name,
+   column_name)
+AS
+SELECT c.conname,
+       cl.relname,
+       a.attname
+  FROM pg_trigger t INNER JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+                    INNER JOIN pg_proc p ON (t.tgfoid = p.oid)
+                    INNER JOIN pg_class cl ON (t.tgrelid = cl.oid)
+                    CROSS JOIN LATERAL UNNEST(t.tgattr) AS co(n)
+                    INNER JOIN pg_attribute a ON (a.attrelid = cl.oid AND attnum = co.n)
+ WHERE t.tgisinternal
+   AND p.proname = 'assertion_check'
+   AND (tgtype & (1 << 4)) > 0;
+CREATE OR REPLACE VIEW invalidating_summary
+  (assertion_name,
+   operations)
+AS
+SELECT assertion_name,
+       string_agg(operation, ' ' ORDER BY operation)
+  FROM (SELECT assertion_name,
+               operation ||'('|| string_agg(relation_name, ', ' ORDER BY relation_name) ||')'
+          FROM invalidating_operation
+         WHERE operation <> 'UPDATE'
+         GROUP BY assertion_name,
+                  operation
+         UNION
+        SELECT assertion_name,
+               operation ||'('|| string_agg(relation_name ||'.'|| column_name, ', ' ORDER BY relation_name, column_name) ||')'
+          FROM invalidating_by_update_of_column JOIN invalidating_operation USING (assertion_name, relation_name)
+         WHERE operation = 'UPDATE'
+         GROUP BY assertion_name,
+                  operation)
+    AS v(assertion_name, operation)
+ GROUP BY assertion_name;
+CREATE OR REPLACE FUNCTION have_identical_invalidating_operations
+  (a text, b text)
+RETURNS TABLE (predicate text, correct text)
+AS $$
+  SELECT 'assertion "'|| a ||'" has identical invalidating operations to assertion "'|| b ||'"',
+         CASE WHEN
+           NOT EXISTS (SELECT relation_name, operation
+                         FROM invalidating_operation
+                        WHERE assertion_name = a
+                       EXCEPT 
+                       SELECT relation_name, operation
+                         FROM invalidating_operation
+                        WHERE assertion_name = b) AND
+           NOT EXISTS (SELECT relation_name, column_name
+                         FROM invalidating_by_update_of_column
+                        WHERE assertion_name = a
+                       EXCEPT
+                       SELECT relation_name, column_name
+                         FROM invalidating_by_update_of_column
+                        WHERE assertion_name = b) THEN 'YES'
+                                                  ELSE 'NO' END
+$$ LANGUAGE SQL;
+COMMIT;
+BEGIN TRANSACTION;
+--
+-- Perform some basic sanity checking on creating assertions
+--
+CREATE TABLE test1 (a int, b text);
+CREATE ASSERTION foo CHECK (1 < 2);
+CREATE ASSERTION a2 CHECK ((SELECT count(*) FROM test1) < 5);
+DELETE FROM test1;
+INSERT INTO test1 VALUES (1, 'one');
+INSERT INTO test1 VALUES (2, 'two');
+INSERT INTO test1 VALUES (3, 'three');
+INSERT INTO test1 VALUES (4, 'four');
+SAVEPOINT pre_insert_too_many;
+INSERT INTO test1 VALUES (5, 'five');
+ERROR:  assertion "a2" violated
+ROLLBACK TO SAVEPOINT pre_insert_too_many;
+SELECT constraint_schema,
+       constraint_name
+  FROM information_schema.assertions
+ ORDER BY 1, 2;
+ constraint_schema | constraint_name 
+-------------------+-----------------
+ public            | a2
+ public            | foo
+(2 rows)
+
+\dQ
+                        List of assertions
+ Schema | Name |             Definition             | Description 
+--------+------+------------------------------------+-------------
+ public | a2   | CHECK ((( SELECT count(*) AS count+| 
+        |      |    FROM test1)) < 5)               | 
+ public | foo  | CHECK (1 < 2)                      | 
+(2 rows)
+
+ALTER ASSERTION a2 RENAME TO a3;
+SAVEPOINT pre_rename_foo;
+ALTER ASSERTION foo RENAME TO a3; -- fails
+ERROR:  assertion "a3" already exists
+ROLLBACK TO SAVEPOINT pre_rename_foo;
+DROP ASSERTION foo;
+SAVEPOINT pre_drop_test1;
+DROP TABLE test1; -- fails
+ERROR:  cannot drop table test1 because other objects depend on it
+DETAIL:  constraint a3 depends on table test1
+HINT:  Use DROP ... CASCADE to drop the dependent objects too.
+ROLLBACK TO SAVEPOINT pre_drop_test1;
+DROP TABLE test1 CASCADE;
+NOTICE:  drop cascades to constraint a3
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving various operators, functions and casts
+-- 
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+INSERT INTO t (n, p) VALUES (20, TRUE);
+CREATE ASSERTION is_distinct_from CHECK (10 IS DISTINCT FROM (SELECT MIN(n) FROM t));
+CREATE ASSERTION is_not_distinct_from CHECK (20 IS NOT DISTINCT FROM (SELECT MIN(n) FROM t));
+CREATE ASSERTION null_if CHECK (NULLIF((SELECT BOOL_AND(p) FROM t), FALSE));
+CREATE ASSERTION coerce_to_boolean_from_min CHECK (CAST((SELECT MIN(n) FROM t) AS BOOLEAN));
+CREATE ASSERTION coerce_to_boolean_from_bool_and CHECK (CAST((SELECT BOOL_AND(p) FROM t) AS BOOLEAN));
+CREATE ASSERTION coerce_to_boolean_from_boolean CHECK (CAST((SELECT TRUE FROM t) AS BOOLEAN));
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving function calls
+--
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL, d DATE NOT NULL);
+CREATE FUNCTION f(n INTEGER) RETURNS INTEGER
+AS $$
+  SELECT n * 2
+$$ LANGUAGE SQL;
+CREATE FUNCTION r(n INTEGER) RETURNS TABLE (m INTEGER )
+AS $$
+  SELECT m
+    FROM t
+   WHERE n > r.n
+$$ LANGUAGE SQL;
+CREATE ASSERTION age_of_d_in_t CHECK (
+  NOT EXISTS (
+    SELECT FROM t
+     WHERE AGE(DATE '01-01-2018') > INTERVAL '10 days' -- AGE(DATE) is built-in SQL
+  )
+);
+CREATE ASSERTION use_f CHECK (f(0) = 0);
+CREATE ASSERTION use_f_in_predicate CHECK (NOT EXISTS (SELECT FROM t WHERE f(n) = 20));
+CREATE ASSERTION use_f_in_target CHECK (NOT EXISTS (SELECT f(n) FROM t));
+CREATE ASSERTION use_r_in_from CHECK (NOT EXISTS (SELECT FROM r(100)));
+CREATE ASSERTION use_r_in_target CHECK (NOT EXISTS (SELECT r(100)));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (COALESCE(operations, 'NONE') = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('age_of_d_in_t',      'INSERT(t)'),
+       ('use_f',              'NONE'),
+       ('use_f_in_predicate', 'INSERT(t) UPDATE(t.n)'),
+       ('use_f_in_target',    'INSERT(t)'),
+       ('use_r_in_from',      'INSERT(t) UPDATE(t.m, t.n)'), -- TODO should _from and _target be the same?
+       ('use_r_in_target',    'INSERT(t) UPDATE(t.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+   assertion_name   |           actual           |          expected          | correct 
+--------------------+----------------------------+----------------------------+---------
+ age_of_d_in_t      | INSERT(t)                  | INSERT(t)                  | YES
+ use_f              | NONE                       | NONE                       | YES
+ use_f_in_predicate | INSERT(t) UPDATE(t.n)      | INSERT(t) UPDATE(t.n)      | YES
+ use_f_in_target    | INSERT(t)                  | INSERT(t)                  | YES
+ use_r_in_from      | INSERT(t) UPDATE(t.m, t.n) | INSERT(t) UPDATE(t.m, t.n) | YES
+ use_r_in_target    | INSERT(t) UPDATE(t.n)      | INSERT(t) UPDATE(t.n)      | YES
+(6 rows)
+
+CREATE FUNCTION g(n INTEGER) RETURNS INTEGER
+AS $$
+BEGIN
+  RETURN n * 2;
+END;
+$$ LANGUAGE PLPGSQL;
+-- Use of functions other than internal or those implemented in SQL are illegal
+CREATE ASSERTION use_g_in_from CHECK (NOT EXISTS (SELECT FROM g(100))); -- fails
+ERROR:  function "g" uses unsupported language "plpgsql"
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving EXISTS and NOT EXISTS
+--
+CREATE TABLE r (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+CREATE TABLE t1 (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+CREATE TABLE t2 (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+INSERT INTO r (n) VALUES (1);
+INSERT INTO t (n, m) VALUES (0, 0);
+INSERT INTO t1 (n, m) VALUES (0, 0);
+INSERT INTO t2 (n, m) VALUES (0, 0);
+CREATE ASSERTION exists_no_predicate CHECK (
+  EXISTS (SELECT FROM r)
+);
+CREATE ASSERTION exists_with_predicate CHECK (
+  EXISTS (SELECT FROM r WHERE n > 0)
+);
+CREATE ASSERTION not_exists_no_predicate CHECK (
+  NOT EXISTS (SELECT FROM s)
+);
+CREATE ASSERTION not_exists_with_predicate CHECK (
+  NOT EXISTS (SELECT FROM r WHERE n < 1)
+);
+CREATE ASSERTION direct_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t WHERE m = 0)
+);
+-- TODO These can be optimised, at least if the set operation is UNION.
+CREATE ASSERTION except_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t1 WHERE m = 0 EXCEPT SELECT n FROM t2 WHERE m = 1)
+);
+CREATE ASSERTION intersect_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t1 WHERE m = 0 INTERSECT SELECT n FROM t2 WHERE m = 0)
+);
+CREATE ASSERTION union_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t1 WHERE m = 0 UNION SELECT n FROM t2 WHERE m = 0)
+);
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('exists_no_predicate',            'DELETE(r)'),
+       ('exists_with_predicate',          'DELETE(r) UPDATE(r.n)'),
+       ('not_exists_no_predicate',        'INSERT(s)'),
+       ('not_exists_with_predicate',      'INSERT(r) UPDATE(r.n)'),
+       ('direct_subject_of_an_exists',    'DELETE(t) UPDATE(t.m)'),
+       ('except_subject_of_an_exists',    'DELETE(t1) INSERT(t2) UPDATE(t1.m, t1.n, t2.m, t2.n)'),
+       ('intersect_subject_of_an_exists', 'DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)'),
+       ('union_subject_of_an_exists',     'DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+         assertion_name         |                        actual                        |                       expected                       | correct 
+--------------------------------+------------------------------------------------------+------------------------------------------------------+---------
+ direct_subject_of_an_exists    | DELETE(t) UPDATE(t.m)                                | DELETE(t) UPDATE(t.m)                                | YES
+ except_subject_of_an_exists    | DELETE(t1) INSERT(t2) UPDATE(t1.m, t1.n, t2.m, t2.n) | DELETE(t1) INSERT(t2) UPDATE(t1.m, t1.n, t2.m, t2.n) | YES
+ exists_no_predicate            | DELETE(r)                                            | DELETE(r)                                            | YES
+ exists_with_predicate          | DELETE(r) UPDATE(r.n)                                | DELETE(r) UPDATE(r.n)                                | YES
+ intersect_subject_of_an_exists | DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)        | DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)        | YES
+ not_exists_no_predicate        | INSERT(s)                                            | INSERT(s)                                            | YES
+ not_exists_with_predicate      | INSERT(r) UPDATE(r.n)                                | INSERT(r) UPDATE(r.n)                                | YES
+ union_subject_of_an_exists     | DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)        | DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)        | YES
+(8 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving NOT
+--
+CREATE TABLE r (p BOOLEAN NOT NULL PRIMARY KEY);
+INSERT INTO r (p) VALUES (TRUE);
+CREATE ASSERTION a CHECK (EXISTS (SELECT FROM r WHERE p));
+CREATE ASSERTION b CHECK (NOT EXISTS (SELECT FROM r WHERE NOT p));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('a', 'DELETE(r) UPDATE(r.p)'),
+       ('b', 'INSERT(r) UPDATE(r.p)')) -- NOT(x) and x have opposite invalidating operations
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name |        actual         |       expected        | correct 
+----------------+-----------------------+-----------------------+---------
+ a              | DELETE(r) UPDATE(r.p) | DELETE(r) UPDATE(r.p) | YES
+ b              | INSERT(r) UPDATE(r.p) | INSERT(r) UPDATE(r.p) | YES
+(2 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving set operations INTERSECT, UNION, and EXCEPT
+--
+CREATE TABLE r (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY);
+INSERT INTO t (n) VALUES (0);
+CREATE ASSERTION except_operands CHECK (NOT EXISTS (SELECT FROM r EXCEPT SELECT FROM s));
+CREATE ASSERTION intersect_operands CHECK (NOT EXISTS (SELECT FROM r INTERSECT SELECT FROM s));
+CREATE ASSERTION union_operands CHECK (EXISTS (SELECT FROM s UNION SELECT FROM t));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('except_operands',    'DELETE(s) INSERT(r)'),
+       ('intersect_operands', 'INSERT(r, s)'),
+       ('union_operands',     'DELETE(s, t)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+   assertion_name   |       actual        |      expected       | correct 
+--------------------+---------------------+---------------------+---------
+ except_operands    | DELETE(s) INSERT(r) | DELETE(s) INSERT(r) | YES
+ intersect_operands | INSERT(r, s)        | INSERT(r, s)        | YES
+ union_operands     | DELETE(s, t)        | DELETE(s, t)        | YES
+(3 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving COUNT aggregations
+--
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+INSERT INTO s VALUES (1, 2);
+CREATE ASSERTION ge_all_count CHECK (1 >= ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION ge_any_count CHECK (1 >= ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION ge_count     CHECK (1 >=     (SELECT COUNT(*) FROM s));
+CREATE ASSERTION gt_all_count CHECK (2 >  ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION gt_any_count CHECK (2 >  ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION gt_count     CHECK (2 >      (SELECT COUNT(*) FROM s));
+CREATE ASSERTION le_all_count CHECK (1 <= ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION le_any_count CHECK (0 <= ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION le_count     CHECK (0 <=     (SELECT COUNT(*) FROM s));
+CREATE ASSERTION lt_all_count CHECK (0 <  ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION lt_any_count CHECK (0 <  ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION lt_count     CHECK (0 <      (SELECT COUNT(*) FROM s));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('ge_all_count', 'INSERT(s)'),
+       ('ge_any_count', 'INSERT(s)'),
+       ('ge_count',     'INSERT(s)'),
+       ('gt_all_count', 'INSERT(s)'),
+       ('gt_any_count', 'INSERT(s)'),
+       ('gt_count',     'INSERT(s)'),
+       ('le_all_count', 'DELETE(s)'),
+       ('le_any_count', 'DELETE(s)'),
+       ('le_count',     'DELETE(s)'),
+       ('lt_all_count', 'DELETE(s)'),
+       ('lt_any_count', 'DELETE(s)'),
+       ('lt_count',     'DELETE(s)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name |  actual   | expected  | correct 
+----------------+-----------+-----------+---------
+ ge_all_count   | INSERT(s) | INSERT(s) | YES
+ ge_any_count   | INSERT(s) | INSERT(s) | YES
+ ge_count       | INSERT(s) | INSERT(s) | YES
+ gt_all_count   | INSERT(s) | INSERT(s) | YES
+ gt_any_count   | INSERT(s) | INSERT(s) | YES
+ gt_count       | INSERT(s) | INSERT(s) | YES
+ le_all_count   | DELETE(s) | DELETE(s) | YES
+ le_any_count   | DELETE(s) | DELETE(s) | YES
+ le_count       | DELETE(s) | DELETE(s) | YES
+ lt_all_count   | DELETE(s) | DELETE(s) | YES
+ lt_any_count   | DELETE(s) | DELETE(s) | YES
+ lt_count       | DELETE(s) | DELETE(s) | YES
+(12 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving MIN aggregations
+--
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+INSERT INTO s VALUES (1, 2);
+CREATE ASSERTION ge_any_min CHECK (1 >= ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION ge_all_min CHECK (1 >= ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION ge_min     CHECK (1 >=     (SELECT MIN(n) FROM s));
+CREATE ASSERTION gt_any_min CHECK (2 >  ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION gt_all_min CHECK (2 >  ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION gt_min     CHECK (2 >      (SELECT MIN(n) FROM s));
+CREATE ASSERTION le_any_min CHECK (0 <= ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION le_all_min CHECK (0 <= ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION le_min     CHECK (0 <=     (SELECT MIN(n) FROM s));
+CREATE ASSERTION lt_any_min CHECK (0 <  ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION lt_all_min CHECK (0 <  ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION lt_min     CHECK (0 <      (SELECT MIN(n) FROM s));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('ge_all_min', 'DELETE(s) UPDATE(s.n)'),
+       ('ge_any_min', 'DELETE(s) UPDATE(s.n)'),
+       ('ge_min',     'DELETE(s) UPDATE(s.n)'),
+       ('gt_all_min', 'DELETE(s) UPDATE(s.n)'),
+       ('gt_any_min', 'DELETE(s) UPDATE(s.n)'),
+       ('gt_min',     'DELETE(s) UPDATE(s.n)'),
+       ('le_all_min', 'INSERT(s) UPDATE(s.n)'),
+       ('le_any_min', 'INSERT(s) UPDATE(s.n)'),
+       ('le_min',     'INSERT(s) UPDATE(s.n)'),
+       ('lt_all_min', 'INSERT(s) UPDATE(s.n)'),
+       ('lt_any_min', 'INSERT(s) UPDATE(s.n)'),
+       ('lt_min',     'INSERT(s) UPDATE(s.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name |        actual         |       expected        | correct 
+----------------+-----------------------+-----------------------+---------
+ ge_all_min     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ ge_any_min     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ ge_min         | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ gt_all_min     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ gt_any_min     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ gt_min         | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ le_all_min     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ le_any_min     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ le_min         | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ lt_all_min     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ lt_any_min     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ lt_min         | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+(12 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving MAX aggregations
+--
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+INSERT INTO s VALUES (1, 2);
+CREATE ASSERTION ge_any_max CHECK (1 >= ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION ge_all_max CHECK (1 >= ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION ge_max     CHECK (1 >=     (SELECT MAX(n) FROM s));
+CREATE ASSERTION gt_all_max CHECK (2 >  ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION gt_any_max CHECK (2 >  ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION gt_max     CHECK (2 >      (SELECT MAX(n) FROM s));
+CREATE ASSERTION le_all_max CHECK (0 <= ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION le_any_max CHECK (0 <= ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION le_max     CHECK (0 <=     (SELECT MAX(n) FROM s));
+CREATE ASSERTION lt_all_max CHECK (0 <  ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION lt_any_max CHECK (0 <  ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION lt_max     CHECK (0 <      (SELECT MAX(n) FROM s));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('ge_all_max', 'INSERT(s) UPDATE(s.n)'),
+       ('ge_any_max', 'INSERT(s) UPDATE(s.n)'),
+       ('ge_max',     'INSERT(s) UPDATE(s.n)'),
+       ('gt_all_max', 'INSERT(s) UPDATE(s.n)'),
+       ('gt_any_max', 'INSERT(s) UPDATE(s.n)'),
+       ('gt_max',     'INSERT(s) UPDATE(s.n)'),
+       ('le_all_max', 'DELETE(s) UPDATE(s.n)'),
+       ('le_any_max', 'DELETE(s) UPDATE(s.n)'),
+       ('le_max',     'DELETE(s) UPDATE(s.n)'),
+       ('lt_all_max', 'DELETE(s) UPDATE(s.n)'),
+       ('lt_any_max', 'DELETE(s) UPDATE(s.n)'),
+       ('lt_max',     'DELETE(s) UPDATE(s.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name |        actual         |       expected        | correct 
+----------------+-----------------------+-----------------------+---------
+ ge_all_max     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ ge_any_max     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ ge_max         | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ gt_all_max     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ gt_any_max     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ gt_max         | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ le_all_max     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ le_any_max     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ le_max         | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ lt_all_max     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ lt_any_max     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ lt_max         | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+(12 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving BOOL_AND aggregations
+--
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+INSERT INTO t (n, p) VALUES (0, TRUE);
+CREATE ASSERTION eq_bool_and     CHECK (TRUE  =      (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION eq_any_bool_and CHECK (TRUE  =  ANY (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION eq_all_bool_and CHECK (TRUE  =  ALL (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION ne_bool_and     CHECK (FALSE <>     (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION ne_any_bool_and CHECK (FALSE <> ANY (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION ne_all_bool_and CHECK (FALSE <> ALL (SELECT BOOL_AND(p) FROM t));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('eq_all_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('eq_any_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('eq_bool_and',     'INSERT(t) UPDATE(t.p)'),
+       ('ne_all_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('ne_any_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('ne_bool_and',     'INSERT(t) UPDATE(t.p)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name  |        actual         |       expected        | correct 
+-----------------+-----------------------+-----------------------+---------
+ eq_all_bool_and | INSERT(t) UPDATE(t.p) | INSERT(t) UPDATE(t.p) | YES
+ eq_any_bool_and | INSERT(t) UPDATE(t.p) | INSERT(t) UPDATE(t.p) | YES
+ eq_bool_and     | INSERT(t) UPDATE(t.p) | INSERT(t) UPDATE(t.p) | YES
+ ne_all_bool_and | INSERT(t) UPDATE(t.p) | INSERT(t) UPDATE(t.p) | YES
+ ne_any_bool_and | INSERT(t) UPDATE(t.p) | INSERT(t) UPDATE(t.p) | YES
+ ne_bool_and     | INSERT(t) UPDATE(t.p) | INSERT(t) UPDATE(t.p) | YES
+(6 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving BOOL_OR aggregations
+--
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+INSERT INTO t (n, p) VALUES (0, TRUE);
+CREATE ASSERTION eq_bool_or     CHECK (TRUE  =      (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION eq_any_bool_or CHECK (TRUE  =  ANY (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION eq_all_bool_or CHECK (TRUE  =  ALL (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION ne_bool_or     CHECK (FALSE <>     (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION ne_any_bool_or CHECK (FALSE <> ANY (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION ne_all_bool_or CHECK (FALSE <> ALL (SELECT BOOL_OR(p) FROM t));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('eq_all_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('eq_any_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('eq_bool_or',     'DELETE(t) UPDATE(t.p)'),
+       ('ne_all_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('ne_any_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('ne_bool_or',     'DELETE(t) UPDATE(t.p)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name |        actual         |       expected        | correct 
+----------------+-----------------------+-----------------------+---------
+ eq_all_bool_or | DELETE(t) UPDATE(t.p) | DELETE(t) UPDATE(t.p) | YES
+ eq_any_bool_or | DELETE(t) UPDATE(t.p) | DELETE(t) UPDATE(t.p) | YES
+ eq_bool_or     | DELETE(t) UPDATE(t.p) | DELETE(t) UPDATE(t.p) | YES
+ ne_all_bool_or | DELETE(t) UPDATE(t.p) | DELETE(t) UPDATE(t.p) | YES
+ ne_any_bool_or | DELETE(t) UPDATE(t.p) | DELETE(t) UPDATE(t.p) | YES
+ ne_bool_or     | DELETE(t) UPDATE(t.p) | DELETE(t) UPDATE(t.p) | YES
+(6 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving window functions
+--
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+-- Regular window function
+CREATE ASSERTION alternate_p CHECK (
+  NOT EXISTS (
+    SELECT FROM (
+      SELECT LAG(p, 1, NOT p) OVER n <> p
+         AND LEAD(p, 1, NOT p) OVER n <> p
+        FROM t
+      WINDOW n AS (ORDER BY n)
+    ) AS v(q)
+    WHERE NOT q
+  )
+);
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('alternate_p', 'DELETE(t) INSERT(t) UPDATE(t.n, t.p)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name |                actual                |               expected               | correct 
+----------------+--------------------------------------+--------------------------------------+---------
+ alternate_p    | DELETE(t) INSERT(t) UPDATE(t.n, t.p) | DELETE(t) INSERT(t) UPDATE(t.n, t.p) | YES
+(1 row)
+
+INSERT INTO t (n, p) VALUES (10, TRUE);
+INSERT INTO t (n, p) VALUES (20, FALSE);
+INSERT INTO t (n, p) VALUES (30, TRUE);
+SAVEPOINT pre_insert;
+INSERT INTO t (n, p) VALUES (40, TRUE);
+ERROR:  assertion "alternate_p" violated
+ROLLBACK TO SAVEPOINT pre_insert;
+SAVEPOINT pre_delete;
+DELETE FROM t WHERE n = 20;
+ERROR:  assertion "alternate_p" violated
+ROLLBACK TO SAVEPOINT pre_delete;
+SAVEPOINT pre_update;
+UPDATE t SET p = NOT p WHERE n = 20;
+ERROR:  assertion "alternate_p" violated
+ROLLBACK TO SAVEPOINT pre_update;
+DROP ASSERTION alternate_p;
+-- Aggregate function over a window
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+INSERT INTO s (n, m)
+SELECT n, (2 * n)
+  FROM GENERATE_SERIES(0, 9) AS ns(n);
+CREATE ASSERTION max_over_window CHECK ((10, 20) > ALL (SELECT n, MAX(m) OVER (ORDER BY n) FROM s));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('max_over_window', 'INSERT(s) UPDATE(s.m, s.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name  |           actual           |          expected          | correct 
+-----------------+----------------------------+----------------------------+---------
+ max_over_window | INSERT(s) UPDATE(s.m, s.n) | INSERT(s) UPDATE(s.m, s.n) | YES
+(1 row)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions containing a comparison should have the same invalidating
+-- operations as an expression containing the inverse comparison operation
+-- and where the operands have been switched
+--
+CREATE TABLE r (n INTEGER NOT NULL PRIMARY KEY);
+INSERT INTO r (n) VALUES (9);
+-- ">" and "<" are opposites
+CREATE ASSERTION a CHECK (10 > (SELECT MIN(n) FROM r));
+CREATE ASSERTION b CHECK ((SELECT MIN(n) FROM r) < 10);
+-- "<" and ">" are opposites
+CREATE ASSERTION c CHECK (8 < (SELECT MIN(n) FROM r));
+CREATE ASSERTION d CHECK ((SELECT MIN(n) FROM r) > 8);
+-- ">=" and "<=" are opposites
+CREATE ASSERTION e CHECK (9 >= (SELECT MIN(n) FROM r));
+CREATE ASSERTION f CHECK ((SELECT MIN(n) FROM r) <= 9);
+-- "<=" and ">=" are opposites
+CREATE ASSERTION g CHECK (9 <= (SELECT MIN(n) FROM r));
+CREATE ASSERTION h CHECK ((SELECT MIN(n) FROM r) >= 9);
+SELECT (test).predicate, (test).correct
+  FROM (
+VALUES ('a', 'b'),
+       ('c', 'd'),
+       ('e', 'f'),
+       ('g', 'h'))
+    AS v(a, b)
+ CROSS JOIN LATERAL (SELECT have_identical_invalidating_operations(v.a, v.b))
+    AS w(test)
+ ORDER BY 1, 2;
+                              predicate                               | correct 
+----------------------------------------------------------------------+---------
+ assertion "a" has identical invalidating operations to assertion "b" | YES
+ assertion "c" has identical invalidating operations to assertion "d" | YES
+ assertion "e" has identical invalidating operations to assertion "f" | YES
+ assertion "g" has identical invalidating operations to assertion "h" | YES
+(4 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- The INFORMATION_SCHEMA should contain the correct information
+--
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+CREATE ASSERTION a CHECK (NOT EXISTS (SELECT FROM t WHERE p));
+SELECT predicate,
+       CASE WHEN
+         truth THEN 'YES'
+               ELSE 'NO'
+       END AS correct
+  FROM ( 
+VALUES ('INFORMATION_SCHEMA.CONSTRAINT_TABLE_USAGE contains only the correct tables',
+        EXISTS (
+          SELECT FROM information_schema.constraint_table_usage
+           WHERE (constraint_name, table_name) = ('a', 't'))
+        AND NOT EXISTS (
+          SELECT FROM information_schema.constraint_table_usage
+           WHERE constraint_name = 'a'
+             AND table_name <> 't')),
+       ('INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE contains only the correct columns (t.p)',
+        EXISTS (
+          SELECT FROM information_schema.constraint_column_usage
+           WHERE (constraint_name, table_name, column_name) = ('a', 't', 'p'))
+        AND NOT EXISTS (
+          SELECT FROM information_schema.constraint_column_usage
+           WHERE constraint_name ='a'
+             AND (table_name, column_name) <> ('t', 'p'))),
+       ('INFORMATION_SCHEMA.ASSERTIONS contains only the correct assertions',
+        EXISTS (
+          SELECT FROM information_schema.assertions
+           WHERE constraint_name = 'a')
+        AND NOT EXISTS (
+          SELECT FROM information_schema.assertions
+           WHERE constraint_name <> 'a')))
+    AS v(predicate, truth);
+                                     predicate                                      | correct 
+------------------------------------------------------------------------------------+---------
+ INFORMATION_SCHEMA.CONSTRAINT_TABLE_USAGE contains only the correct tables         | YES
+ INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE contains only the correct columns (t.p) | YES
+ INFORMATION_SCHEMA.ASSERTIONS contains only the correct assertions                 | YES
+(3 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+-- TODO This needs rethinking
+/*
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+CREATE VIEW v AS SELECT * FROM s INNER JOIN t USING (n);
+
+CREATE ASSERTION a CHECK (NOT EXISTS (SELECT FROM v));
+
+-- we should depend on the view not the tables
+SELECT OK(depends_on('a', 'v'),
+          'Assertion depends upon the view v it references');
+SELECT OK(NOT depends_on('a', 's'),
+          'Assertion does not depend upon the table s referenced in the view v');
+SELECT OK(NOT depends_on('a', 't'),
+          'Assertion does not depend upon the table t referenced in the view v');
+
+-- we should trigger on the tables and not the view
+SELECT OK(EXISTS(SELECT FROM assertion_check_operation
+                  WHERE (assertion_name, relation_name) = ('a', 's')),
+          'Assertion is checked on modifications to table s');
+SELECT OK(EXISTS(SELECT FROM assertion_check_operation
+                  WHERE (assertion_name, relation_name) = ('a', 't')),
+          'Assertion is checked on modifications to table t');
+SELECT OK(NOT EXISTS(SELECT FROM assertion_check_operation
+                      WHERE (assertion_name, relation_name) = ('a', 'v')),
+          'Assertion is not checked on modifications to view v');
+*/
+ROLLBACK;
+-- TODO test commonalities between count, min, max, etc, for optimisations
+-- TODO ensure window function aggregates are treated the same as regular aggregates
+-- TODO ensure that conflicting aggregate functions are not incorrectly optimised
+-- TODO ensure that recorded dependencies are correct (traversal into functions and views)
+BEGIN TRANSACTION;
+DROP FUNCTION have_identical_invalidating_operations;
+DROP VIEW invalidating_summary;
+DROP VIEW invalidating_by_update_of_column;
+DROP VIEW invalidating_operation;
+COMMIT;
diff --git a/src/test/regress/parallel_schedule b/src/test/regress/parallel_schedule
index e224977791..64a3d783b2 100644
--- a/src/test/regress/parallel_schedule
+++ b/src/test/regress/parallel_schedule
@@ -60,7 +60,7 @@ test: create_index create_view
 # ----------
 # Another group of parallel tests
 # ----------
-test: create_aggregate create_function_3 create_cast constraints triggers inherit create_table_like typed_table vacuum drop_if_exists updatable_views rolenames roleattributes create_am hash_func
+test: create_aggregate create_function_3 create_cast constraints triggers inherit create_table_like typed_table vacuum drop_if_exists updatable_views rolenames roleattributes create_am assertions hash_func
 
 # ----------
 # sanity_check does a vacuum, affecting the sort order of SELECT *
diff --git a/src/test/regress/serial_schedule b/src/test/regress/serial_schedule
index 9fc5f1a268..9aeb21a3ac 100644
--- a/src/test/regress/serial_schedule
+++ b/src/test/regress/serial_schedule
@@ -58,6 +58,7 @@ test: create_function_1
 test: create_type
 test: create_table
 test: create_function_2
+test: assertions
 test: copy
 test: copyselect
 test: copydml
diff --git a/src/test/regress/sql/assertions.sql b/src/test/regress/sql/assertions.sql
new file mode 100644
index 0000000000..f270698da1
--- /dev/null
+++ b/src/test/regress/sql/assertions.sql
@@ -0,0 +1,775 @@
+
+BEGIN TRANSACTION;
+
+--
+-- Create some helper views and functions to allow us to more easily
+-- assert which operations will cause an assertion to be checked.
+--
+
+CREATE OR REPLACE VIEW invalidating_operation
+  (assertion_name,
+   relation_name,
+   operation)
+AS
+SELECT c.conname,
+       cl.relname,
+       v.operation
+  FROM pg_trigger t
+  JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+  JOIN pg_proc p ON (t.tgfoid = p.oid)
+  JOIN pg_class cl ON (t.tgrelid = cl.oid)
+  JOIN (VALUES ('INSERT', 1<<2),
+               ('DELETE', 1<<3|1<<5),
+               ('UPDATE', 1<<4))
+    AS v(operation, mask) ON ((v.mask & tgtype) > 0)
+ WHERE t.tgisinternal
+   AND p.proname = 'assertion_check';
+
+CREATE OR REPLACE VIEW invalidating_by_update_of_column
+  (assertion_name,
+   relation_name,
+   column_name)
+AS
+SELECT c.conname,
+       cl.relname,
+       a.attname
+  FROM pg_trigger t INNER JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+                    INNER JOIN pg_proc p ON (t.tgfoid = p.oid)
+                    INNER JOIN pg_class cl ON (t.tgrelid = cl.oid)
+                    CROSS JOIN LATERAL UNNEST(t.tgattr) AS co(n)
+                    INNER JOIN pg_attribute a ON (a.attrelid = cl.oid AND attnum = co.n)
+ WHERE t.tgisinternal
+   AND p.proname = 'assertion_check'
+   AND (tgtype & (1 << 4)) > 0;
+
+CREATE OR REPLACE VIEW invalidating_summary
+  (assertion_name,
+   operations)
+AS
+SELECT assertion_name,
+       string_agg(operation, ' ' ORDER BY operation)
+  FROM (SELECT assertion_name,
+               operation ||'('|| string_agg(relation_name, ', ' ORDER BY relation_name) ||')'
+          FROM invalidating_operation
+         WHERE operation <> 'UPDATE'
+         GROUP BY assertion_name,
+                  operation
+         UNION
+        SELECT assertion_name,
+               operation ||'('|| string_agg(relation_name ||'.'|| column_name, ', ' ORDER BY relation_name, column_name) ||')'
+          FROM invalidating_by_update_of_column JOIN invalidating_operation USING (assertion_name, relation_name)
+         WHERE operation = 'UPDATE'
+         GROUP BY assertion_name,
+                  operation)
+    AS v(assertion_name, operation)
+ GROUP BY assertion_name;
+
+CREATE OR REPLACE FUNCTION have_identical_invalidating_operations
+  (a text, b text)
+RETURNS TABLE (predicate text, correct text)
+AS $$
+  SELECT 'assertion "'|| a ||'" has identical invalidating operations to assertion "'|| b ||'"',
+         CASE WHEN
+           NOT EXISTS (SELECT relation_name, operation
+                         FROM invalidating_operation
+                        WHERE assertion_name = a
+                       EXCEPT 
+                       SELECT relation_name, operation
+                         FROM invalidating_operation
+                        WHERE assertion_name = b) AND
+           NOT EXISTS (SELECT relation_name, column_name
+                         FROM invalidating_by_update_of_column
+                        WHERE assertion_name = a
+                       EXCEPT
+                       SELECT relation_name, column_name
+                         FROM invalidating_by_update_of_column
+                        WHERE assertion_name = b) THEN 'YES'
+                                                  ELSE 'NO' END
+$$ LANGUAGE SQL;
+
+COMMIT;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Perform some basic sanity checking on creating assertions
+--
+
+CREATE TABLE test1 (a int, b text);
+
+CREATE ASSERTION foo CHECK (1 < 2);
+CREATE ASSERTION a2 CHECK ((SELECT count(*) FROM test1) < 5);
+
+DELETE FROM test1;
+INSERT INTO test1 VALUES (1, 'one');
+INSERT INTO test1 VALUES (2, 'two');
+INSERT INTO test1 VALUES (3, 'three');
+INSERT INTO test1 VALUES (4, 'four');
+
+SAVEPOINT pre_insert_too_many;
+INSERT INTO test1 VALUES (5, 'five');
+ROLLBACK TO SAVEPOINT pre_insert_too_many;
+
+SELECT constraint_schema,
+       constraint_name
+  FROM information_schema.assertions
+ ORDER BY 1, 2;
+
+\dQ
+
+ALTER ASSERTION a2 RENAME TO a3;
+
+SAVEPOINT pre_rename_foo;
+ALTER ASSERTION foo RENAME TO a3; -- fails
+ROLLBACK TO SAVEPOINT pre_rename_foo;
+
+DROP ASSERTION foo;
+
+SAVEPOINT pre_drop_test1;
+DROP TABLE test1; -- fails
+ROLLBACK TO SAVEPOINT pre_drop_test1;
+
+DROP TABLE test1 CASCADE;
+
+ROLLBACK;
+
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving various operators, functions and casts
+-- 
+
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+
+INSERT INTO t (n, p) VALUES (20, TRUE);
+
+CREATE ASSERTION is_distinct_from CHECK (10 IS DISTINCT FROM (SELECT MIN(n) FROM t));
+CREATE ASSERTION is_not_distinct_from CHECK (20 IS NOT DISTINCT FROM (SELECT MIN(n) FROM t));
+CREATE ASSERTION null_if CHECK (NULLIF((SELECT BOOL_AND(p) FROM t), FALSE));
+CREATE ASSERTION coerce_to_boolean_from_min CHECK (CAST((SELECT MIN(n) FROM t) AS BOOLEAN));
+CREATE ASSERTION coerce_to_boolean_from_bool_and CHECK (CAST((SELECT BOOL_AND(p) FROM t) AS BOOLEAN));
+CREATE ASSERTION coerce_to_boolean_from_boolean CHECK (CAST((SELECT TRUE FROM t) AS BOOLEAN));
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving function calls
+--
+
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL, d DATE NOT NULL);
+
+CREATE FUNCTION f(n INTEGER) RETURNS INTEGER
+AS $$
+  SELECT n * 2
+$$ LANGUAGE SQL;
+
+CREATE FUNCTION r(n INTEGER) RETURNS TABLE (m INTEGER )
+AS $$
+  SELECT m
+    FROM t
+   WHERE n > r.n
+$$ LANGUAGE SQL;
+
+CREATE ASSERTION age_of_d_in_t CHECK (
+  NOT EXISTS (
+    SELECT FROM t
+     WHERE AGE(DATE '01-01-2018') > INTERVAL '10 days' -- AGE(DATE) is built-in SQL
+  )
+);
+CREATE ASSERTION use_f CHECK (f(0) = 0);
+CREATE ASSERTION use_f_in_predicate CHECK (NOT EXISTS (SELECT FROM t WHERE f(n) = 20));
+CREATE ASSERTION use_f_in_target CHECK (NOT EXISTS (SELECT f(n) FROM t));
+CREATE ASSERTION use_r_in_from CHECK (NOT EXISTS (SELECT FROM r(100)));
+CREATE ASSERTION use_r_in_target CHECK (NOT EXISTS (SELECT r(100)));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (COALESCE(operations, 'NONE') = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('age_of_d_in_t',      'INSERT(t)'),
+       ('use_f',              'NONE'),
+       ('use_f_in_predicate', 'INSERT(t) UPDATE(t.n)'),
+       ('use_f_in_target',    'INSERT(t)'),
+       ('use_r_in_from',      'INSERT(t) UPDATE(t.m, t.n)'), -- TODO should _from and _target be the same?
+       ('use_r_in_target',    'INSERT(t) UPDATE(t.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+CREATE FUNCTION g(n INTEGER) RETURNS INTEGER
+AS $$
+BEGIN
+  RETURN n * 2;
+END;
+$$ LANGUAGE PLPGSQL;
+
+-- Use of functions other than internal or those implemented in SQL are illegal
+CREATE ASSERTION use_g_in_from CHECK (NOT EXISTS (SELECT FROM g(100))); -- fails
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving EXISTS and NOT EXISTS
+--
+
+CREATE TABLE r (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+CREATE TABLE t1 (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+CREATE TABLE t2 (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+
+INSERT INTO r (n) VALUES (1);
+INSERT INTO t (n, m) VALUES (0, 0);
+INSERT INTO t1 (n, m) VALUES (0, 0);
+INSERT INTO t2 (n, m) VALUES (0, 0);
+
+CREATE ASSERTION exists_no_predicate CHECK (
+  EXISTS (SELECT FROM r)
+);
+
+CREATE ASSERTION exists_with_predicate CHECK (
+  EXISTS (SELECT FROM r WHERE n > 0)
+);
+
+CREATE ASSERTION not_exists_no_predicate CHECK (
+  NOT EXISTS (SELECT FROM s)
+);
+
+CREATE ASSERTION not_exists_with_predicate CHECK (
+  NOT EXISTS (SELECT FROM r WHERE n < 1)
+);
+
+CREATE ASSERTION direct_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t WHERE m = 0)
+);
+
+-- TODO These can be optimised, at least if the set operation is UNION.
+CREATE ASSERTION except_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t1 WHERE m = 0 EXCEPT SELECT n FROM t2 WHERE m = 1)
+);
+
+CREATE ASSERTION intersect_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t1 WHERE m = 0 INTERSECT SELECT n FROM t2 WHERE m = 0)
+);
+
+CREATE ASSERTION union_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t1 WHERE m = 0 UNION SELECT n FROM t2 WHERE m = 0)
+);
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('exists_no_predicate',            'DELETE(r)'),
+       ('exists_with_predicate',          'DELETE(r) UPDATE(r.n)'),
+       ('not_exists_no_predicate',        'INSERT(s)'),
+       ('not_exists_with_predicate',      'INSERT(r) UPDATE(r.n)'),
+       ('direct_subject_of_an_exists',    'DELETE(t) UPDATE(t.m)'),
+       ('except_subject_of_an_exists',    'DELETE(t1) INSERT(t2) UPDATE(t1.m, t1.n, t2.m, t2.n)'),
+       ('intersect_subject_of_an_exists', 'DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)'),
+       ('union_subject_of_an_exists',     'DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving NOT
+--
+
+CREATE TABLE r (p BOOLEAN NOT NULL PRIMARY KEY);
+
+INSERT INTO r (p) VALUES (TRUE);
+
+CREATE ASSERTION a CHECK (EXISTS (SELECT FROM r WHERE p));
+CREATE ASSERTION b CHECK (NOT EXISTS (SELECT FROM r WHERE NOT p));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('a', 'DELETE(r) UPDATE(r.p)'),
+       ('b', 'INSERT(r) UPDATE(r.p)')) -- NOT(x) and x have opposite invalidating operations
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving set operations INTERSECT, UNION, and EXCEPT
+--
+
+CREATE TABLE r (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY);
+
+INSERT INTO t (n) VALUES (0);
+
+CREATE ASSERTION except_operands CHECK (NOT EXISTS (SELECT FROM r EXCEPT SELECT FROM s));
+CREATE ASSERTION intersect_operands CHECK (NOT EXISTS (SELECT FROM r INTERSECT SELECT FROM s));
+CREATE ASSERTION union_operands CHECK (EXISTS (SELECT FROM s UNION SELECT FROM t));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('except_operands',    'DELETE(s) INSERT(r)'),
+       ('intersect_operands', 'INSERT(r, s)'),
+       ('union_operands',     'DELETE(s, t)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving COUNT aggregations
+--
+
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+
+INSERT INTO s VALUES (1, 2);
+
+CREATE ASSERTION ge_all_count CHECK (1 >= ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION ge_any_count CHECK (1 >= ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION ge_count     CHECK (1 >=     (SELECT COUNT(*) FROM s));
+CREATE ASSERTION gt_all_count CHECK (2 >  ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION gt_any_count CHECK (2 >  ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION gt_count     CHECK (2 >      (SELECT COUNT(*) FROM s));
+CREATE ASSERTION le_all_count CHECK (1 <= ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION le_any_count CHECK (0 <= ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION le_count     CHECK (0 <=     (SELECT COUNT(*) FROM s));
+CREATE ASSERTION lt_all_count CHECK (0 <  ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION lt_any_count CHECK (0 <  ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION lt_count     CHECK (0 <      (SELECT COUNT(*) FROM s));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('ge_all_count', 'INSERT(s)'),
+       ('ge_any_count', 'INSERT(s)'),
+       ('ge_count',     'INSERT(s)'),
+       ('gt_all_count', 'INSERT(s)'),
+       ('gt_any_count', 'INSERT(s)'),
+       ('gt_count',     'INSERT(s)'),
+       ('le_all_count', 'DELETE(s)'),
+       ('le_any_count', 'DELETE(s)'),
+       ('le_count',     'DELETE(s)'),
+       ('lt_all_count', 'DELETE(s)'),
+       ('lt_any_count', 'DELETE(s)'),
+       ('lt_count',     'DELETE(s)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving MIN aggregations
+--
+
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+
+INSERT INTO s VALUES (1, 2);
+
+CREATE ASSERTION ge_any_min CHECK (1 >= ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION ge_all_min CHECK (1 >= ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION ge_min     CHECK (1 >=     (SELECT MIN(n) FROM s));
+CREATE ASSERTION gt_any_min CHECK (2 >  ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION gt_all_min CHECK (2 >  ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION gt_min     CHECK (2 >      (SELECT MIN(n) FROM s));
+CREATE ASSERTION le_any_min CHECK (0 <= ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION le_all_min CHECK (0 <= ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION le_min     CHECK (0 <=     (SELECT MIN(n) FROM s));
+CREATE ASSERTION lt_any_min CHECK (0 <  ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION lt_all_min CHECK (0 <  ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION lt_min     CHECK (0 <      (SELECT MIN(n) FROM s));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('ge_all_min', 'DELETE(s) UPDATE(s.n)'),
+       ('ge_any_min', 'DELETE(s) UPDATE(s.n)'),
+       ('ge_min',     'DELETE(s) UPDATE(s.n)'),
+       ('gt_all_min', 'DELETE(s) UPDATE(s.n)'),
+       ('gt_any_min', 'DELETE(s) UPDATE(s.n)'),
+       ('gt_min',     'DELETE(s) UPDATE(s.n)'),
+       ('le_all_min', 'INSERT(s) UPDATE(s.n)'),
+       ('le_any_min', 'INSERT(s) UPDATE(s.n)'),
+       ('le_min',     'INSERT(s) UPDATE(s.n)'),
+       ('lt_all_min', 'INSERT(s) UPDATE(s.n)'),
+       ('lt_any_min', 'INSERT(s) UPDATE(s.n)'),
+       ('lt_min',     'INSERT(s) UPDATE(s.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving MAX aggregations
+--
+
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+
+INSERT INTO s VALUES (1, 2);
+
+CREATE ASSERTION ge_any_max CHECK (1 >= ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION ge_all_max CHECK (1 >= ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION ge_max     CHECK (1 >=     (SELECT MAX(n) FROM s));
+CREATE ASSERTION gt_all_max CHECK (2 >  ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION gt_any_max CHECK (2 >  ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION gt_max     CHECK (2 >      (SELECT MAX(n) FROM s));
+CREATE ASSERTION le_all_max CHECK (0 <= ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION le_any_max CHECK (0 <= ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION le_max     CHECK (0 <=     (SELECT MAX(n) FROM s));
+CREATE ASSERTION lt_all_max CHECK (0 <  ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION lt_any_max CHECK (0 <  ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION lt_max     CHECK (0 <      (SELECT MAX(n) FROM s));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('ge_all_max', 'INSERT(s) UPDATE(s.n)'),
+       ('ge_any_max', 'INSERT(s) UPDATE(s.n)'),
+       ('ge_max',     'INSERT(s) UPDATE(s.n)'),
+       ('gt_all_max', 'INSERT(s) UPDATE(s.n)'),
+       ('gt_any_max', 'INSERT(s) UPDATE(s.n)'),
+       ('gt_max',     'INSERT(s) UPDATE(s.n)'),
+       ('le_all_max', 'DELETE(s) UPDATE(s.n)'),
+       ('le_any_max', 'DELETE(s) UPDATE(s.n)'),
+       ('le_max',     'DELETE(s) UPDATE(s.n)'),
+       ('lt_all_max', 'DELETE(s) UPDATE(s.n)'),
+       ('lt_any_max', 'DELETE(s) UPDATE(s.n)'),
+       ('lt_max',     'DELETE(s) UPDATE(s.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving BOOL_AND aggregations
+--
+
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+INSERT INTO t (n, p) VALUES (0, TRUE);
+
+CREATE ASSERTION eq_bool_and     CHECK (TRUE  =      (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION eq_any_bool_and CHECK (TRUE  =  ANY (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION eq_all_bool_and CHECK (TRUE  =  ALL (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION ne_bool_and     CHECK (FALSE <>     (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION ne_any_bool_and CHECK (FALSE <> ANY (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION ne_all_bool_and CHECK (FALSE <> ALL (SELECT BOOL_AND(p) FROM t));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('eq_all_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('eq_any_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('eq_bool_and',     'INSERT(t) UPDATE(t.p)'),
+       ('ne_all_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('ne_any_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('ne_bool_and',     'INSERT(t) UPDATE(t.p)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving BOOL_OR aggregations
+--
+
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+INSERT INTO t (n, p) VALUES (0, TRUE);
+
+CREATE ASSERTION eq_bool_or     CHECK (TRUE  =      (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION eq_any_bool_or CHECK (TRUE  =  ANY (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION eq_all_bool_or CHECK (TRUE  =  ALL (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION ne_bool_or     CHECK (FALSE <>     (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION ne_any_bool_or CHECK (FALSE <> ANY (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION ne_all_bool_or CHECK (FALSE <> ALL (SELECT BOOL_OR(p) FROM t));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('eq_all_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('eq_any_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('eq_bool_or',     'DELETE(t) UPDATE(t.p)'),
+       ('ne_all_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('ne_any_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('ne_bool_or',     'DELETE(t) UPDATE(t.p)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving window functions
+--
+
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+
+-- Regular window function
+CREATE ASSERTION alternate_p CHECK (
+  NOT EXISTS (
+    SELECT FROM (
+      SELECT LAG(p, 1, NOT p) OVER n <> p
+         AND LEAD(p, 1, NOT p) OVER n <> p
+        FROM t
+      WINDOW n AS (ORDER BY n)
+    ) AS v(q)
+    WHERE NOT q
+  )
+);
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('alternate_p', 'DELETE(t) INSERT(t) UPDATE(t.n, t.p)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+INSERT INTO t (n, p) VALUES (10, TRUE);
+INSERT INTO t (n, p) VALUES (20, FALSE);
+INSERT INTO t (n, p) VALUES (30, TRUE);
+
+SAVEPOINT pre_insert;
+INSERT INTO t (n, p) VALUES (40, TRUE);
+ROLLBACK TO SAVEPOINT pre_insert;
+
+SAVEPOINT pre_delete;
+DELETE FROM t WHERE n = 20;
+ROLLBACK TO SAVEPOINT pre_delete;
+
+SAVEPOINT pre_update;
+UPDATE t SET p = NOT p WHERE n = 20;
+ROLLBACK TO SAVEPOINT pre_update;
+
+DROP ASSERTION alternate_p;
+
+-- Aggregate function over a window
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+
+INSERT INTO s (n, m)
+SELECT n, (2 * n)
+  FROM GENERATE_SERIES(0, 9) AS ns(n);
+
+CREATE ASSERTION max_over_window CHECK ((10, 20) > ALL (SELECT n, MAX(m) OVER (ORDER BY n) FROM s));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('max_over_window', 'INSERT(s) UPDATE(s.m, s.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions containing a comparison should have the same invalidating
+-- operations as an expression containing the inverse comparison operation
+-- and where the operands have been switched
+--
+
+CREATE TABLE r (n INTEGER NOT NULL PRIMARY KEY);
+
+INSERT INTO r (n) VALUES (9);
+
+-- ">" and "<" are opposites
+CREATE ASSERTION a CHECK (10 > (SELECT MIN(n) FROM r));
+CREATE ASSERTION b CHECK ((SELECT MIN(n) FROM r) < 10);
+
+-- "<" and ">" are opposites
+CREATE ASSERTION c CHECK (8 < (SELECT MIN(n) FROM r));
+CREATE ASSERTION d CHECK ((SELECT MIN(n) FROM r) > 8);
+
+-- ">=" and "<=" are opposites
+CREATE ASSERTION e CHECK (9 >= (SELECT MIN(n) FROM r));
+CREATE ASSERTION f CHECK ((SELECT MIN(n) FROM r) <= 9);
+
+-- "<=" and ">=" are opposites
+CREATE ASSERTION g CHECK (9 <= (SELECT MIN(n) FROM r));
+CREATE ASSERTION h CHECK ((SELECT MIN(n) FROM r) >= 9);
+
+SELECT (test).predicate, (test).correct
+  FROM (
+VALUES ('a', 'b'),
+       ('c', 'd'),
+       ('e', 'f'),
+       ('g', 'h'))
+    AS v(a, b)
+ CROSS JOIN LATERAL (SELECT have_identical_invalidating_operations(v.a, v.b))
+    AS w(test)
+ ORDER BY 1, 2;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- The INFORMATION_SCHEMA should contain the correct information
+--
+
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+CREATE ASSERTION a CHECK (NOT EXISTS (SELECT FROM t WHERE p));
+
+SELECT predicate,
+       CASE WHEN
+         truth THEN 'YES'
+               ELSE 'NO'
+       END AS correct
+  FROM ( 
+VALUES ('INFORMATION_SCHEMA.CONSTRAINT_TABLE_USAGE contains only the correct tables',
+        EXISTS (
+          SELECT FROM information_schema.constraint_table_usage
+           WHERE (constraint_name, table_name) = ('a', 't'))
+        AND NOT EXISTS (
+          SELECT FROM information_schema.constraint_table_usage
+           WHERE constraint_name = 'a'
+             AND table_name <> 't')),
+       ('INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE contains only the correct columns (t.p)',
+        EXISTS (
+          SELECT FROM information_schema.constraint_column_usage
+           WHERE (constraint_name, table_name, column_name) = ('a', 't', 'p'))
+        AND NOT EXISTS (
+          SELECT FROM information_schema.constraint_column_usage
+           WHERE constraint_name ='a'
+             AND (table_name, column_name) <> ('t', 'p'))),
+       ('INFORMATION_SCHEMA.ASSERTIONS contains only the correct assertions',
+        EXISTS (
+          SELECT FROM information_schema.assertions
+           WHERE constraint_name = 'a')
+        AND NOT EXISTS (
+          SELECT FROM information_schema.assertions
+           WHERE constraint_name <> 'a')))
+    AS v(predicate, truth);
+
+ROLLBACK;
+
+BEGIN TRANSACTION;
+-- TODO This needs rethinking
+/*
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+CREATE VIEW v AS SELECT * FROM s INNER JOIN t USING (n);
+
+CREATE ASSERTION a CHECK (NOT EXISTS (SELECT FROM v));
+
+-- we should depend on the view not the tables
+SELECT OK(depends_on('a', 'v'),
+          'Assertion depends upon the view v it references');
+SELECT OK(NOT depends_on('a', 's'),
+          'Assertion does not depend upon the table s referenced in the view v');
+SELECT OK(NOT depends_on('a', 't'),
+          'Assertion does not depend upon the table t referenced in the view v');
+
+-- we should trigger on the tables and not the view
+SELECT OK(EXISTS(SELECT FROM assertion_check_operation
+                  WHERE (assertion_name, relation_name) = ('a', 's')),
+          'Assertion is checked on modifications to table s');
+SELECT OK(EXISTS(SELECT FROM assertion_check_operation
+                  WHERE (assertion_name, relation_name) = ('a', 't')),
+          'Assertion is checked on modifications to table t');
+SELECT OK(NOT EXISTS(SELECT FROM assertion_check_operation
+                      WHERE (assertion_name, relation_name) = ('a', 'v')),
+          'Assertion is not checked on modifications to view v');
+*/
+ROLLBACK;
+
+-- TODO test commonalities between count, min, max, etc, for optimisations
+-- TODO ensure window function aggregates are treated the same as regular aggregates
+-- TODO ensure that conflicting aggregate functions are not incorrectly optimised
+-- TODO ensure that recorded dependencies are correct (traversal into functions and views)
+
+BEGIN TRANSACTION;
+
+DROP FUNCTION have_identical_invalidating_operations;
+DROP VIEW invalidating_summary;
+DROP VIEW invalidating_by_update_of_column;
+DROP VIEW invalidating_operation;
+
+COMMIT;
-- 
2.15.0

From 293d6214bc04810459c3f120aca5ea545d07b045 Mon Sep 17 00:00:00 2001
From: Joe Wildish <joe@elusive.cx>
Date: Sun, 18 Mar 2018 12:04:59 +0000
Subject: [PATCH] SQL ASSERTION prototype

---
 doc/src/sgml/ddl.sgml                      |   31 +
 doc/src/sgml/ref/allfiles.sgml             |    3 +
 doc/src/sgml/ref/alter_assertion.sgml      |  139 ++++
 doc/src/sgml/ref/create_assertion.sgml     |  133 ++++
 doc/src/sgml/ref/drop_assertion.sgml       |  115 +++
 doc/src/sgml/reference.sgml                |    3 +
 src/backend/catalog/aclchk.c               |   33 +
 src/backend/catalog/information_schema.sql |   60 +-
 src/backend/catalog/namespace.c            |  121 +++
 src/backend/catalog/objectaddress.c        |   11 +
 src/backend/catalog/pg_constraint.c        |   20 +-
 src/backend/commands/alter.c               |    6 +
 src/backend/commands/constraint.c          | 1090 +++++++++++++++++++++++++++-
 src/backend/commands/event_trigger.c       |    2 +
 src/backend/nodes/copyfuncs.c              |   14 +
 src/backend/nodes/equalfuncs.c             |   12 +
 src/backend/parser/gram.y                  |   80 +-
 src/backend/parser/parse_agg.c             |    2 +
 src/backend/parser/parse_expr.c            |    2 +
 src/backend/parser/parse_func.c            |    4 +
 src/backend/tcop/utility.c                 |   20 +
 src/backend/utils/cache/lsyscache.c        |   19 +
 src/bin/psql/command.c                     |    3 +
 src/bin/psql/describe.c                    |   92 +++
 src/bin/psql/describe.h                    |    3 +
 src/bin/psql/help.c                        |    1 +
 src/bin/psql/tab-complete.c                |   30 +-
 src/include/catalog/namespace.h            |    1 +
 src/include/catalog/pg_constraint.h        |    3 +-
 src/include/catalog/pg_constraint_fn.h     |    2 +-
 src/include/catalog/pg_proc.h              |    4 +
 src/include/commands/constraint.h          |   10 +
 src/include/nodes/nodes.h                  |    1 +
 src/include/nodes/parsenodes.h             |   11 +
 src/include/parser/parse_node.h            |    1 +
 src/include/utils/acl.h                    |    1 +
 src/include/utils/lsyscache.h              |    1 +
 src/test/regress/expected/assertions.out   |  779 ++++++++++++++++++++
 src/test/regress/parallel_schedule         |    2 +-
 src/test/regress/serial_schedule           |    1 +
 src/test/regress/sql/assertions.sql        |  775 ++++++++++++++++++++
 41 files changed, 3572 insertions(+), 69 deletions(-)
 create mode 100644 doc/src/sgml/ref/alter_assertion.sgml
 create mode 100644 doc/src/sgml/ref/create_assertion.sgml
 create mode 100644 doc/src/sgml/ref/drop_assertion.sgml
 create mode 100644 src/include/commands/constraint.h
 create mode 100644 src/test/regress/expected/assertions.out
 create mode 100644 src/test/regress/sql/assertions.sql

diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml
index 3a54ba9d5a..81fde6403a 100644
--- a/doc/src/sgml/ddl.sgml
+++ b/doc/src/sgml/ddl.sgml
@@ -917,6 +917,37 @@ CREATE TABLE circles (
     of the type specified in the constraint declaration.
    </para>
   </sect2>
+
+  <sect2 id="ddl-constraints-assertions">
+   <title>Assertions</title>
+   
+   <indexterm zone="ddl-constraints-assertions">
+    <primary>assertion</primary>
+   </indexterm>
+
+   <para>
+    An assertion is a constraint that is not part of a table
+    definition.  An assertion can define constraints that evaluate the
+    data across multiple rows of a table beyond what unique and
+    exclusion constraints can do, and assertions can look at the data
+    in multiple tables.
+   </para>
+
+   <para>
+    An assertion is a separate schema object and is created with the
+    command <command>CREATE ASSERTION</command>.  The constraint
+    expression is written as a <literal>CHECK</literal> clause like in
+    check constraints.  For instance, to ensure that there is always
+    at least one entry in the product table:
+<programlisting>
+CREATE ASSERTION products_not_empty CHECK ((SELECT count(*) FROM products) &gt; 0);
+</programlisting>
+    Assertions will often involve aggregate functions computed over
+    entire tables.  Note, however, that this kind of assertion can be
+   quite inefficient and should only be used on tables that are small
+    and change rarely.
+   </para>
+  </sect2>
  </sect1>
 
  <sect1 id="ddl-system-columns">
diff --git a/doc/src/sgml/ref/allfiles.sgml b/doc/src/sgml/ref/allfiles.sgml
index 22e6893211..57badaf157 100644
--- a/doc/src/sgml/ref/allfiles.sgml
+++ b/doc/src/sgml/ref/allfiles.sgml
@@ -7,6 +7,7 @@ Complete list of usable sgml source files in this directory.
 <!-- SQL commands -->
 <!ENTITY abort              SYSTEM "abort.sgml">
 <!ENTITY alterAggregate     SYSTEM "alter_aggregate.sgml">
+<!ENTITY alterAssertion     SYSTEM "alter_assertion.sgml">
 <!ENTITY alterCollation     SYSTEM "alter_collation.sgml">
 <!ENTITY alterConversion    SYSTEM "alter_conversion.sgml">
 <!ENTITY alterDatabase      SYSTEM "alter_database.sgml">
@@ -60,6 +61,7 @@ Complete list of usable sgml source files in this directory.
 <!ENTITY copyTable          SYSTEM "copy.sgml">
 <!ENTITY createAccessMethod SYSTEM "create_access_method.sgml">
 <!ENTITY createAggregate    SYSTEM "create_aggregate.sgml">
+<!ENTITY createAssertion    SYSTEM "create_assertion.sgml">
 <!ENTITY createCast         SYSTEM "create_cast.sgml">
 <!ENTITY createCollation    SYSTEM "create_collation.sgml">
 <!ENTITY createConversion   SYSTEM "create_conversion.sgml">
@@ -107,6 +109,7 @@ Complete list of usable sgml source files in this directory.
 <!ENTITY do                 SYSTEM "do.sgml">
 <!ENTITY dropAccessMethod   SYSTEM "drop_access_method.sgml">
 <!ENTITY dropAggregate      SYSTEM "drop_aggregate.sgml">
+<!ENTITY dropAssertion      SYSTEM "drop_assertion.sgml">
 <!ENTITY dropCast           SYSTEM "drop_cast.sgml">
 <!ENTITY dropCollation      SYSTEM "drop_collation.sgml">
 <!ENTITY dropConversion     SYSTEM "drop_conversion.sgml">
diff --git a/doc/src/sgml/ref/alter_assertion.sgml b/doc/src/sgml/ref/alter_assertion.sgml
new file mode 100644
index 0000000000..b06417f740
--- /dev/null
+++ b/doc/src/sgml/ref/alter_assertion.sgml
@@ -0,0 +1,139 @@
+<!--
+doc/src/sgml/ref/alter_assertion.sgml
+PostgreSQL documentation
+-->
+
+<refentry id="sql-alterassertion">
+
+ <indexterm zone="sql-alterassertion">
+  <primary>ALTER ASSERTION</primary>
+ </indexterm>
+
+ <refmeta>
+  <refentrytitle>ALTER ASSERTION</refentrytitle>
+  <manvolnum>7</manvolnum>
+  <refmiscinfo>SQL - Language Statements</refmiscinfo>
+ </refmeta>
+
+ <refnamediv>
+  <refname>ALTER ASSERTION</refname>
+  <refpurpose>change the definition of an assertion</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+<synopsis>
+ALTER ASSERTION <replaceable>name</replaceable> RENAME TO <replaceable>new_name</replaceable>
+ALTER ASSERTION <replaceable>name</replaceable> OWNER TO <replaceable>new_owner</replaceable>
+ALTER ASSERTION <replaceable>name</replaceable> SET SCHEMA <replaceable>new_schema</replaceable>
+</synopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+  <title>Description</title>
+
+  <para>
+   <command>ALTER ASSERTION</command> changes the definition of an
+   assertion.
+  </para>
+
+  <para>
+   You must own the assertion to use <command>ALTER ASSERTION</command>.  To
+   change the schema of an assertion, you must also have
+   <literal>CREATE</literal> privilege on the new schema.  To alter
+   the owner, you must also be a direct or indirect member of the new
+   owning role, and that role must have <literal>CREATE</literal>
+   privilege on the assertion's schema.  (These restrictions enforce
+   that altering the owner doesn't do anything you couldn't do by
+   dropping and recreating the assertion.  However, a superuser can
+   alter ownership of any assertion anyway.)
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Parameters</title>
+
+  <variablelist>
+   <varlistentry>
+    <term><replaceable class="parameter">name</replaceable></term>
+    <listitem>
+     <para>
+      The name (optionally schema-qualified) of an existing assertion.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><replaceable class="parameter">new_name</replaceable></term>
+    <listitem>
+     <para>
+      The new name of the assertion.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><replaceable class="parameter">new_owner</replaceable></term>
+    <listitem>
+     <para>
+      The new owner of the assertion.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><replaceable class="parameter">new_schema</replaceable></term>
+    <listitem>
+     <para>
+      The new schema for the assertion.
+     </para>
+    </listitem>
+   </varlistentry>
+  </variablelist>
+ </refsect1>
+
+ <refsect1>
+  <title>Examples</title>
+
+  <para>
+   To rename the assertuib <literal>check_size</literal>
+   to <literal>check_count</literal>:
+<programlisting>
+ALTER ASSERTION check_size RENAME TO check_count;
+</programlisting>
+  </para>
+
+  <para>
+   To change the owner of the assertion <literal>check_size</literal>
+   to <literal>joe</literal>:
+<programlisting>
+ALTER ASSERTION check_size OWNER TO joe;
+</programlisting>
+  </para>
+
+  <para>
+   To move the assertion <literal>check_size</literal> into
+   schema <literal>myschema</literal>:
+<programlisting>
+ALTER ASSERTION check_size SET SCHEMA myschema;
+</programlisting>
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Compatibility</title>
+
+  <para>
+   There is no <command>ALTER ASSERTION</command> statement in the SQL
+   standard.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>See Also</title>
+
+  <simplelist type="inline">
+   <member><xref linkend="sql-createassertion"/></member>
+   <member><xref linkend="sql-dropassertion"/></member>
+  </simplelist>
+ </refsect1>
+</refentry>
diff --git a/doc/src/sgml/ref/create_assertion.sgml b/doc/src/sgml/ref/create_assertion.sgml
new file mode 100644
index 0000000000..b36d1b4ecb
--- /dev/null
+++ b/doc/src/sgml/ref/create_assertion.sgml
@@ -0,0 +1,133 @@
+<!--
+doc/src/sgml/ref/create_assertion.sgml
+PostgreSQL documentation
+-->
+
+<refentry id="sql-createassertion">
+ <indexterm zone="sql-createassertion">
+  <primary>CREATE ASSERTION</primary>
+ </indexterm>
+
+ <refmeta>
+  <refentrytitle>CREATE ASSERTION</refentrytitle>
+  <manvolnum>7</manvolnum>
+  <refmiscinfo>SQL - Language Statements</refmiscinfo>
+ </refmeta>
+
+ <refnamediv>
+  <refname>CREATE ASSERTION</refname>
+  <refpurpose>define a new assertion</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+<synopsis>
+CREATE ASSERTION <replaceable class="parameter">name</replaceable> CHECK ( <replaceable class="parameter">name</replaceable> ) [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
+</synopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+  <title>Description</title>
+
+  <para>
+   <command>CREATE ASSERTION</command> creates an assertion.  An
+   assertion is a check constraint that is independent of a table row
+   and a table.  It can therefore be used to enforce more complex
+   constraints across multiple table rows and across multiple tables.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Parameters</title>
+
+  <variablelist>
+   <varlistentry>
+    <term><replaceable class="parameter">name</replaceable></term>
+    <listitem>
+     <para>
+      The name (optionally schema-qualified) of the assertion to
+      create.  Assertions use the same namespace as constraints on
+      tables.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>CHECK ( <replaceable class="parameter">expression</replaceable> )</literal></term>
+    <listitem>
+     <para>
+      The <literal>CHECK</literal> clause specifies an expression producing a
+      Boolean result which the database must satisfy at all times for a
+      data change operation to succeed.  Expressions evaluating
+      to TRUE or UNKNOWN succeed.  Should the result of a data change
+      operation produce a FALSE result an error exception is
+      raised and the change is not made.
+     </para>
+
+     <para>
+      The check expression typically involves subselects in order to
+      read data from tables.  See the examples below.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>DEFERRABLE</literal></term>
+    <term><literal>NOT DEFERRABLE</literal></term>
+    <term><literal>INITIALLY IMMEDIATE</literal></term>
+    <term><literal>INITIALLY DEFERRED</literal></term>
+    <listitem>
+     <para>
+      These clauses control the deferrability of the constraint.  See
+      <xref linkend="sql-createtable"/> for an explanation.
+     </para>
+    </listitem>
+   </varlistentry>
+  </variablelist>
+ </refsect1>
+
+ <refsect1>
+  <title>Notes</title>
+
+  <para>
+   More specialized constraint forms such as table check constraints,
+   foreign-key constraints, or exclusion constraints should be used
+   instead when applicable, because they will be more efficient.
+  </para>
+
+  <para>
+   Assertion checks are not specially optimized.  For example,
+   checking the row count of a large table in an assertion will be
+   just as slow as implementing the check manually.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Examples</title>
+
+  <para>
+   Check that the table <literal>table1</literal> has at most 30 rows:
+<programlisting>
+CREATE ASSERTION table1_max30 CHECK ((SELECT count(*) FROM table1) &lt;= 30);
+</programlisting>
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Compatibility</title>
+
+  <para>
+   <command>CREATE ASSERTION</command> conforms to the SQL standard.
+   The PostgreSQL implementation has certain restrictions on what
+   check expressions are allowed in assertions.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>See Also</title>
+
+  <simplelist type="inline">
+   <member><xref linkend="sql-alterassertion"/></member>
+   <member><xref linkend="sql-dropassertion"/></member>
+  </simplelist>
+ </refsect1>
+</refentry>
diff --git a/doc/src/sgml/ref/drop_assertion.sgml b/doc/src/sgml/ref/drop_assertion.sgml
new file mode 100644
index 0000000000..39a60a0d29
--- /dev/null
+++ b/doc/src/sgml/ref/drop_assertion.sgml
@@ -0,0 +1,115 @@
+<!--
+doc/src/sgml/ref/drop_assertion.sgml
+PostgreSQL documentation
+-->
+
+<refentry id="sql-dropassertion">
+
+ <indexterm zone="sql-dropassertion">
+  <primary>DROP ASSERTION</primary>
+ </indexterm>
+
+ <refmeta>
+  <refentrytitle>DROP ASSERTION</refentrytitle>
+  <manvolnum>7</manvolnum>
+  <refmiscinfo>SQL - Language Statements</refmiscinfo>
+ </refmeta>
+
+ <refnamediv>
+  <refname>DROP ASSERTION</refname>
+  <refpurpose>remove an assertion</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+<synopsis>
+DROP ASSERTION [ IF EXISTS ] <replaceable class="parameter">name</replaceable> [, ...] [ CASCADE | RESTRICT ]
+</synopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+  <title>Description</title>
+
+  <para>
+   <command>DROP ASSERTION</command> removes an existing assertion. To
+   execute this command the current user must be the owner of the
+   assertion.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Parameters</title>
+
+  <variablelist>
+
+   <varlistentry>
+    <term><literal>IF EXISTS</literal></term>
+    <listitem>
+     <para>
+      Do not throw an error if the assertion does not exist. A notice
+      is issued in this case.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><replaceable class="parameter">name</replaceable></term>
+    <listitem>
+     <para>
+      The name (optionally schema-qualified) of an existing assertion.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>CASCADE</literal></term>
+    <listitem>
+     <para>
+      Automatically drop objects that depend on the assertion.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>RESTRICT</literal></term>
+    <listitem>
+     <para>
+      Refuse to drop the assertion if any objects depend on it.  This
+      is the default.
+     </para>
+    </listitem>
+   </varlistentry>
+  </variablelist>
+ </refsect1>
+
+ <refsect1>
+  <title>Examples</title>
+
+  <para>
+   To remove the assertion <literal>check_size</literal>:
+<programlisting>
+DROP ASSERTION check_size;
+</programlisting>
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Compatibility</title>
+
+  <para>
+   This command conforms to the SQL standard, except that the standard
+   only allows one assertion to be dropped per command, and apart from
+   the <literal>IF EXISTS</literal> option, which is
+   a <productname>PostgreSQL</productname> extension.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>See Also</title>
+
+  <simplelist type="inline">
+   <member><xref linkend="sql-alterassertion"/></member>
+   <member><xref linkend="sql-createassertion"/></member>
+  </simplelist>
+ </refsect1>
+
+</refentry>
diff --git a/doc/src/sgml/reference.sgml b/doc/src/sgml/reference.sgml
index d27fb414f7..9300f2d9fc 100644
--- a/doc/src/sgml/reference.sgml
+++ b/doc/src/sgml/reference.sgml
@@ -35,6 +35,7 @@
 
    &abort;
    &alterAggregate;
+   &alterAssertion;
    &alterCollation;
    &alterConversion;
    &alterDatabase;
@@ -88,6 +89,7 @@
    &copyTable;
    &createAccessMethod;
    &createAggregate;
+   &createAssertion;
    &createCast;
    &createCollation;
    &createConversion;
@@ -135,6 +137,7 @@
    &do;
    &dropAccessMethod;
    &dropAggregate;
+   &dropAssertion;
    &dropCast;
    &dropCollation;
    &dropConversion;
diff --git a/src/backend/catalog/aclchk.c b/src/backend/catalog/aclchk.c
index 0648539796..e804e6d493 100644
--- a/src/backend/catalog/aclchk.c
+++ b/src/backend/catalog/aclchk.c
@@ -3362,6 +3362,9 @@ aclcheck_error(AclResult aclerr, ObjectType objtype,
 					case OBJECT_AGGREGATE:
 						msg = gettext_noop("permission denied for aggregate %s");
 						break;
+					case OBJECT_ASSERTION:
+						msg = gettext_noop("permission denied for assertion %s");
+						break;
 					case OBJECT_COLLATION:
 						msg = gettext_noop("permission denied for collation %s");
 						break;
@@ -3493,6 +3496,9 @@ aclcheck_error(AclResult aclerr, ObjectType objtype,
 					case OBJECT_AGGREGATE:
 						msg = gettext_noop("must be owner of aggregate %s");
 						break;
+					case OBJECT_ASSERTION:
+						msg = gettext_noop("must be owner of assertion %s");
+						break;
 					case OBJECT_COLLATION:
 						msg = gettext_noop("must be owner of collation %s");
 						break;
@@ -5211,6 +5217,33 @@ pg_collation_ownercheck(Oid coll_oid, Oid roleid)
 	return has_privs_of_role(roleid, ownerId);
 }
 
+/*
+ * Ownership check for a constraint (specified by OID).
+ */
+bool
+pg_constraint_ownercheck(Oid constr_oid, Oid roleid)
+{
+	HeapTuple   tuple;
+	//Oid           ownerId;
+
+	/* Superusers bypass all permission checking. */
+	if (superuser_arg(roleid))
+		return true;
+
+	tuple = SearchSysCache1(CONSTROID, ObjectIdGetDatum(constr_oid));
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+			    (errcode(ERRCODE_UNDEFINED_OBJECT),
+			     errmsg("constraint with OID %u does not exist", constr_oid)));
+
+	//FIXME: ownerId = ((Form_pg_constraint) GETSTRUCT(tuple))->conowner;
+
+	ReleaseSysCache(tuple);
+
+	//return has_privs_of_role(roleid, ownerId);
+	return true; // for now
+}
+
 /*
  * Ownership check for a conversion (specified by OID).
  */
diff --git a/src/backend/catalog/information_schema.sql b/src/backend/catalog/information_schema.sql
index f4e69f4a26..23cc0759a3 100644
--- a/src/backend/catalog/information_schema.sql
+++ b/src/backend/catalog/information_schema.sql
@@ -285,7 +285,20 @@ GRANT SELECT ON administrable_role_authorizations TO PUBLIC;
  * ASSERTIONS view
  */
 
--- feature not supported
+CREATE VIEW assertions AS
+    SELECT CAST(current_database() AS sql_identifier) AS constraint_catalog,
+           CAST(n.nspname AS sql_identifier) AS constraint_schema,
+           CAST(con.conname AS sql_identifier) AS constraint_name,
+           CAST(CASE WHEN condeferrable THEN 'YES' ELSE 'NO' END
+             AS yes_or_no) AS is_deferrable,
+           CAST(CASE WHEN condeferred THEN 'YES' ELSE 'NO' END
+             AS yes_or_no) AS initially_deferred
+    FROM pg_namespace n, pg_constraint con
+    WHERE n.oid = con.connamespace
+          AND con.conrelid = 0 AND con.contypid = 0;
+          -- TODO: AND pg_has_role(con.conowner, 'USAGE');
+
+GRANT SELECT ON assertions TO PUBLIC;
 
 
 /*
@@ -790,7 +803,7 @@ CREATE VIEW constraint_column_usage AS
            CAST(cstrname AS sql_identifier) AS constraint_name
 
     FROM (
-        /* check constraints */
+        /* assertions and check constraints */
         SELECT DISTINCT nr.nspname, r.relname, r.relowner, a.attname, nc.nspname, c.conname
           FROM pg_namespace nr, pg_class r, pg_attribute a, pg_depend d, pg_namespace nc, pg_constraint c
           WHERE nr.oid = r.relnamespace
@@ -802,7 +815,7 @@ CREATE VIEW constraint_column_usage AS
             AND d.objid = c.oid
             AND c.connamespace = nc.oid
             AND c.contype = 'c'
-            AND r.relkind IN ('r', 'p')
+            AND r.relkind IN ('r', 'p', 'v')
             AND NOT a.attisdropped
 
         UNION ALL
@@ -842,20 +855,41 @@ GRANT SELECT ON constraint_column_usage TO PUBLIC;
 
 CREATE VIEW constraint_table_usage AS
     SELECT CAST(current_database() AS sql_identifier) AS table_catalog,
-           CAST(nr.nspname AS sql_identifier) AS table_schema,
-           CAST(r.relname AS sql_identifier) AS table_name,
+           CAST(tblschema AS sql_identifier) AS table_schema,
+           CAST(tblname AS sql_identifier) AS table_name,
            CAST(current_database() AS sql_identifier) AS constraint_catalog,
-           CAST(nc.nspname AS sql_identifier) AS constraint_schema,
-           CAST(c.conname AS sql_identifier) AS constraint_name
+           CAST(cstrschema AS sql_identifier) AS constraint_schema,
+           CAST(cstrname AS sql_identifier) AS constraint_name
+
+    FROM (
+        /* assertions and check constraints */
+        SELECT DISTINCT nr.nspname, r.relname, r.relowner, nc.nspname, c.conname
+          FROM pg_namespace nr, pg_class r,
+               pg_depend d, pg_namespace nc, pg_constraint c
+         WHERE nr.oid = r.relnamespace
+           AND d.refobjid = r.oid
+           AND c.connamespace = nc.oid
+           AND d.objid = c.oid
+           AND d.refclassid = 'pg_catalog.pg_class'::regclass
+           AND d.classid = 'pg_catalog.pg_constraint'::regclass
+           AND c.contype = 'c'
+           AND r.relkind IN ('r', 'p', 'v')
 
-    FROM pg_constraint c, pg_namespace nc,
-         pg_class r, pg_namespace nr
+        UNION ALL
 
-    WHERE c.connamespace = nc.oid AND r.relnamespace = nr.oid
-          AND ( (c.contype = 'f' AND c.confrelid = r.oid)
+        /* unique/primary key constraints */
+        SELECT nr.nspname, r.relname, r.relowner, nc.nspname, c.conname
+          FROM pg_constraint c, pg_namespace nc,
+               pg_class r, pg_namespace nr
+         WHERE c.connamespace = nc.oid
+           AND r.relnamespace = nr.oid
+           AND ( (c.contype = 'f' AND c.confrelid = r.oid)
              OR (c.contype IN ('p', 'u') AND c.conrelid = r.oid) )
-          AND r.relkind IN ('r', 'p')
-          AND pg_has_role(r.relowner, 'USAGE');
+           AND r.relkind IN ('r', 'p')
+
+    ) AS x (tblschema, tblname, tblowner, cstrschema, cstrname)
+
+    WHERE pg_has_role(x.tblowner, 'USAGE');
 
 GRANT SELECT ON constraint_table_usage TO PUBLIC;
 
diff --git a/src/backend/catalog/namespace.c b/src/backend/catalog/namespace.c
index 52dd400b96..0bb1e31eff 100644
--- a/src/backend/catalog/namespace.c
+++ b/src/backend/catalog/namespace.c
@@ -27,6 +27,7 @@
 #include "catalog/objectaccess.h"
 #include "catalog/pg_authid.h"
 #include "catalog/pg_collation.h"
+#include "catalog/pg_constraint.h"
 #include "catalog/pg_conversion.h"
 #include "catalog/pg_conversion_fn.h"
 #include "catalog/pg_namespace.h"
@@ -57,9 +58,11 @@
 #include "utils/lsyscache.h"
 #include "utils/memutils.h"
 #include "utils/syscache.h"
+#include "utils/fmgroids.h"
 #include "utils/varlena.h"
 
 
+
 /*
  * The namespace search path is a possibly-empty list of namespace OIDs.
  * In addition to the explicit list, implicitly-searched namespaces
@@ -3483,6 +3486,124 @@ PopOverrideSearchPath(void)
 }
 
 
+static Oid
+get_assertion_oid_internal(Relation pg_constraint, char *assertion_name, Oid namespaceId, List *name)
+{
+	SysScanDesc scan;
+	ScanKeyData skey[4];
+	HeapTuple	tuple;
+	Oid			conOid = InvalidOid;
+
+	ScanKeyInit(&skey[0],
+				Anum_pg_constraint_conname,
+				BTEqualStrategyNumber, F_NAMEEQ,
+				PointerGetDatum(assertion_name));
+
+	ScanKeyInit(&skey[1],
+				Anum_pg_constraint_connamespace,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(namespaceId));
+
+	ScanKeyInit(&skey[2],
+				Anum_pg_constraint_conrelid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				InvalidOid);
+
+	ScanKeyInit(&skey[3],
+				Anum_pg_constraint_contypid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				InvalidOid);
+
+	scan = systable_beginscan(pg_constraint, InvalidOid, false,
+							  NULL, 4, skey);
+
+	/*
+	 * Fetch the constraint tuple from pg_constraint.  There may be
+	 * more than one match, because constraints are not required to
+	 * have unique names; if so, error out.
+	 */
+	while (HeapTupleIsValid(tuple = systable_getnext(scan)))
+	{
+		Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(tuple);
+
+		if (OidIsValid(con->conrelid) || OidIsValid(con->contypid))
+			ereport(ERROR,
+					(errmsg("constraint \"%s\" is not an assertion",
+							NameListToString(name))));
+
+		if (strcmp(NameStr(con->conname), assertion_name) == 0)
+		{
+			if (OidIsValid(conOid))
+				ereport(ERROR,
+						(errcode(ERRCODE_DUPLICATE_OBJECT),
+								errmsg("there are multiple assertions named \"%s\"",
+									   NameListToString(name))));
+			conOid = HeapTupleGetOid(tuple);
+		}
+	}
+
+	systable_endscan(scan);
+
+	return conOid;
+}
+
+/*
+ * get_assertion_oid
+ *		Find an assertion with the specified name.
+ *		Returns constraint's OID.
+ */
+Oid
+get_assertion_oid(List *name, bool missing_ok)
+{
+	char	   *schemaname;
+	char	   *assertion_name;
+	Oid			namespaceId;
+	Relation	pg_constraint;
+	Oid			conOid = InvalidOid;
+
+	DeconstructQualifiedName(name, &schemaname, &assertion_name);
+
+	pg_constraint = heap_open(ConstraintRelationId, AccessShareLock);
+
+	if (schemaname)
+	{
+		namespaceId = LookupExplicitNamespace(schemaname, missing_ok);
+		conOid = get_assertion_oid_internal(pg_constraint, assertion_name, namespaceId, name);
+	}
+	else
+	{
+		ListCell   *l;
+
+		recomputeNamespacePath();
+
+		foreach(l, activeSearchPath)
+		{
+			namespaceId = lfirst_oid(l);
+
+			if (namespaceId == myTempNamespace)
+				continue;		/* do not look in temp namespace */
+
+			conOid = get_assertion_oid_internal(pg_constraint, assertion_name, namespaceId, name);
+
+			if (OidIsValid(conOid))
+				break;
+		}
+	}
+
+	heap_close(pg_constraint, AccessShareLock);
+
+	/* If no such constraint exists, complain */
+	if (!OidIsValid(conOid) && !missing_ok)
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+						errmsg("assertion \"%s\" does not exist",
+							   NameListToString(name))));
+
+	return conOid;
+}
+
+
+
 /*
  * get_collation_oid - find a collation by possibly qualified name
  *
diff --git a/src/backend/catalog/objectaddress.c b/src/backend/catalog/objectaddress.c
index 119297b33a..1c9f186d02 100644
--- a/src/backend/catalog/objectaddress.c
+++ b/src/backend/catalog/objectaddress.c
@@ -899,6 +899,11 @@ get_object_address(ObjectType objtype, Node *object,
 				address.objectId = LookupOperWithArgs(castNode(ObjectWithArgs, object), missing_ok);
 				address.objectSubId = 0;
 				break;
+			case OBJECT_ASSERTION:
+				address.classId = ConstraintRelationId;
+				address.objectId = get_assertion_oid(castNode(List, object), missing_ok);
+				address.objectSubId = 0;
+				break;
 			case OBJECT_COLLATION:
 				address.classId = CollationRelationId;
 				address.objectId = get_collation_oid(castNode(List, object), missing_ok);
@@ -2117,6 +2122,7 @@ pg_get_object_address(PG_FUNCTION_ARGS)
 		case OBJECT_FOREIGN_TABLE:
 		case OBJECT_COLUMN:
 		case OBJECT_ATTRIBUTE:
+		case OBJECT_ASSERTION:
 		case OBJECT_COLLATION:
 		case OBJECT_CONVERSION:
 		case OBJECT_STATISTIC_EXT:
@@ -2277,6 +2283,11 @@ check_object_ownership(Oid roleid, ObjectType objtype, ObjectAddress address,
 				aclcheck_error(ACLCHECK_NOT_OWNER, objtype,
 							   strVal((Value *) object));
 			break;
+		case OBJECT_ASSERTION:
+			if (!pg_constraint_ownercheck(address.objectId, roleid))
+				aclcheck_error(ACLCHECK_NOT_OWNER, objtype,
+							   NameListToString(castNode(List, object)));
+			break;
 		case OBJECT_COLLATION:
 			if (!pg_collation_ownercheck(address.objectId, roleid))
 				aclcheck_error(ACLCHECK_NOT_OWNER, objtype,
diff --git a/src/backend/catalog/pg_constraint.c b/src/backend/catalog/pg_constraint.c
index 731c5e4317..08e3e4f9c8 100644
--- a/src/backend/catalog/pg_constraint.c
+++ b/src/backend/catalog/pg_constraint.c
@@ -429,6 +429,13 @@ ConstraintNameIsUsed(ConstraintCategory conCat, Oid objId,
 			found = true;
 			break;
 		}
+		else if (conCat == CONSTRAINT_ASSERTION
+				 && con->conrelid == InvalidOid
+				 && con->contypid == InvalidOid)
+		{
+			found = true;
+			break;
+		}
 	}
 
 	systable_endscan(conscan);
@@ -600,8 +607,7 @@ RemoveConstraintById(Oid conId)
 		 * but we have no such concept at the moment.
 		 */
 	}
-	else
-		elog(ERROR, "constraint %u is not of a known type", conId);
+	/* Else it's an assertion; nothing special for that. */
 
 	/* Fry the constraint itself */
 	CatalogTupleDelete(conDesc, &tup->t_self);
@@ -657,6 +663,16 @@ RenameConstraintById(Oid conId, const char *newname)
 				(errcode(ERRCODE_DUPLICATE_OBJECT),
 				 errmsg("constraint \"%s\" for domain %s already exists",
 						newname, format_type_be(con->contypid))));
+	if (!OidIsValid(con->conrelid) &&
+		!OidIsValid(con->contypid) &&
+		ConstraintNameIsUsed(CONSTRAINT_ASSERTION,
+							 InvalidOid,
+							 con->connamespace,
+							 newname))
+		ereport(ERROR,
+				(errcode(ERRCODE_DUPLICATE_OBJECT),
+						errmsg("assertion \"%s\" already exists",
+							   newname)));
 
 	/* OK, do the rename --- tuple is a copy, so OK to scribble on it */
 	namestrcpy(&(con->conname), newname);
diff --git a/src/backend/commands/alter.c b/src/backend/commands/alter.c
index 0d63866fb0..5cb6e0fe7d 100644
--- a/src/backend/commands/alter.c
+++ b/src/backend/commands/alter.c
@@ -41,6 +41,7 @@
 #include "commands/alter.h"
 #include "commands/collationcmds.h"
 #include "commands/conversioncmds.h"
+#include "commands/constraint.h"
 #include "commands/dbcommands.h"
 #include "commands/defrem.h"
 #include "commands/event_trigger.h"
@@ -326,6 +327,9 @@ ExecRenameStmt(RenameStmt *stmt)
 {
 	switch (stmt->renameType)
 	{
+		case OBJECT_ASSERTION:
+			return RenameAssertion(stmt);
+
 		case OBJECT_TABCONSTRAINT:
 		case OBJECT_DOMCONSTRAINT:
 			return RenameConstraint(stmt);
@@ -491,6 +495,7 @@ ExecAlterObjectSchemaStmt(AlterObjectSchemaStmt *stmt,
 
 			/* generic code path */
 		case OBJECT_AGGREGATE:
+		case OBJECT_ASSERTION:
 		case OBJECT_COLLATION:
 		case OBJECT_CONVERSION:
 		case OBJECT_FUNCTION:
@@ -838,6 +843,7 @@ ExecAlterOwnerStmt(AlterOwnerStmt *stmt)
 
 			/* Generic cases */
 		case OBJECT_AGGREGATE:
+		case OBJECT_ASSERTION:
 		case OBJECT_COLLATION:
 		case OBJECT_CONVERSION:
 		case OBJECT_FUNCTION:
diff --git a/src/backend/commands/constraint.c b/src/backend/commands/constraint.c
index 90f19ad3dd..172508510f 100644
--- a/src/backend/commands/constraint.c
+++ b/src/backend/commands/constraint.c
@@ -11,6 +11,8 @@
  *
  *-------------------------------------------------------------------------
  */
+
+
 #include "postgres.h"
 
 #include "catalog/index.h"
@@ -20,6 +22,40 @@
 #include "utils/rel.h"
 #include "utils/tqual.h"
 
+#include "access/htup_details.h"
+#include "catalog/dependency.h"
+#include "catalog/namespace.h"
+#include "catalog/pg_aggregate.h"
+#include "catalog/pg_constraint.h"
+#include "catalog/pg_constraint_fn.h"
+#include "catalog/pg_operator.h"
+#include "catalog/pg_proc.h"
+#include "catalog/pg_language.h"
+#include "catalog/pg_trigger.h"
+#include "catalog/pg_type.h"
+#include "commands/constraint.h"
+#include "executor/functions.h"
+#include "executor/spi.h"
+#include "miscadmin.h"
+#include "nodes/makefuncs.h"
+#include "nodes/nodeFuncs.h"
+#include "optimizer/planner.h"
+#include "parser/analyze.h"
+#include "parser/parse_coerce.h"
+#include "parser/parse_expr.h"
+#include "parser/parse_node.h"
+#include "parser/parse_relation.h"
+#include "parser/parser.h"
+#include "parser/parsetree.h"
+#include "rewrite/rewriteHandler.h"
+#include "tcop/tcopprot.h"
+#include "utils/acl.h"
+#include "utils/lsyscache.h"
+#include "utils/snapmgr.h"
+#include "utils/syscache.h"
+#include "utils/ruleutils.h"
+#include "utils/fmgroids.h"
+
 
 /*
  * unique_key_recheck - trigger function to do a deferred uniqueness check.
@@ -39,15 +75,15 @@ unique_key_recheck(PG_FUNCTION_ARGS)
 {
 	TriggerData *trigdata = castNode(TriggerData, fcinfo->context);
 	const char *funcname = "unique_key_recheck";
-	HeapTuple	new_row;
+	HeapTuple new_row;
 	ItemPointerData tmptid;
-	Relation	indexRel;
-	IndexInfo  *indexInfo;
-	EState	   *estate;
+	Relation indexRel;
+	IndexInfo *indexInfo;
+	EState *estate;
 	ExprContext *econtext;
 	TupleTableSlot *slot;
-	Datum		values[INDEX_MAX_KEYS];
-	bool		isnull[INDEX_MAX_KEYS];
+	Datum values[INDEX_MAX_KEYS];
+	bool isnull[INDEX_MAX_KEYS];
 
 	/*
 	 * Make sure this is being called as an AFTER ROW trigger.  Note:
@@ -57,15 +93,15 @@ unique_key_recheck(PG_FUNCTION_ARGS)
 	if (!CALLED_AS_TRIGGER(fcinfo))
 		ereport(ERROR,
 				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
-				 errmsg("function \"%s\" was not called by trigger manager",
-						funcname)));
+					errmsg("function \"%s\" was not called by trigger manager",
+						   funcname)));
 
 	if (!TRIGGER_FIRED_AFTER(trigdata->tg_event) ||
 		!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
 		ereport(ERROR,
 				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
-				 errmsg("function \"%s\" must be fired AFTER ROW",
-						funcname)));
+					errmsg("function \"%s\" must be fired AFTER ROW",
+						   funcname)));
 
 	/*
 	 * Get the new data that was inserted/updated.
@@ -78,9 +114,9 @@ unique_key_recheck(PG_FUNCTION_ARGS)
 	{
 		ereport(ERROR,
 				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
-				 errmsg("function \"%s\" must be fired for INSERT or UPDATE",
-						funcname)));
-		new_row = NULL;			/* keep compiler quiet */
+					errmsg("function \"%s\" must be fired for INSERT or UPDATE",
+						   funcname)));
+		new_row = NULL;            /* keep compiler quiet */
 	}
 
 	/*
@@ -194,3 +230,1031 @@ unique_key_recheck(PG_FUNCTION_ARGS)
 
 	return PointerGetDatum(NULL);
 }
+
+
+static void
+test_assertion_expr(char *name, char *expression)
+{
+	char *sql;
+	int returnCode;
+	bool isNull;
+	Datum value;
+
+	if (SPI_connect() != SPI_OK_CONNECT)
+		elog(ERROR, "SPI connect failed when executing ASSERTION statement");
+
+	sql = psprintf("SELECT %s", expression);
+	returnCode = SPI_exec(sql, 1);
+
+	if (returnCode > 0 && SPI_tuptable != NULL)
+	{
+		value = SPI_getbinval(SPI_tuptable->vals[0], SPI_tuptable->tupdesc, 1, &isNull);
+		if (isNull)
+			ereport(ERROR,
+					(errcode(ERRCODE_CHECK_VIOLATION),
+							errmsg("assertion \"%s\" truth is unknown", name)));
+		else if (!isNull && !DatumGetBool(value))
+			ereport(ERROR,
+					(errcode(ERRCODE_CHECK_VIOLATION),
+							errmsg("assertion \"%s\" violated", name)));
+	}
+	else
+		elog(ERROR, "unexpected SPI result when executing ASSERTION statement");
+
+	SPI_finish();
+}
+
+
+Datum
+assertion_check(PG_FUNCTION_ARGS)
+{
+	TriggerData *trigdata = (TriggerData *) fcinfo->context;
+	const char *funcname = "assertion_check";
+	Oid constraintOid;
+	HeapTuple tup;
+	Datum adatum;
+	bool isNull;
+
+	/*
+	 * Make sure this is being called as an AFTER STATEMENT trigger.	Note:
+	 * translatable error strings are shared with ri_triggers.c, so resist the
+	 * temptation to fold the function name into them.
+	 */
+	if (!CALLED_AS_TRIGGER(fcinfo))
+		ereport(ERROR,
+				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
+					errmsg("function \"%s\" was not called by trigger manager",
+						   funcname)));
+
+	if (!TRIGGER_FIRED_AFTER(trigdata->tg_event) ||
+		!TRIGGER_FIRED_FOR_STATEMENT(trigdata->tg_event))
+		ereport(ERROR,
+				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
+					errmsg("function \"%s\" must be fired AFTER STATEMENT",
+						   funcname)));
+
+	constraintOid = trigdata->tg_trigger->tgconstraint;
+	tup = SearchSysCache1(CONSTROID, ObjectIdGetDatum(constraintOid));
+	if (!HeapTupleIsValid(tup))
+		elog(ERROR, "cache lookup failed for constraint %u", constraintOid);
+
+	// XXX bogus
+	adatum = SysCacheGetAttr(CONSTROID, tup,
+							 Anum_pg_constraint_consrc, &isNull);
+	if (isNull)
+		elog(ERROR, "constraint %u has null consrc", constraintOid);
+
+	test_assertion_expr(get_constraint_name(constraintOid), TextDatumGetCString(adatum));
+
+	ReleaseSysCache(tup);
+	return PointerGetDatum(NULL);
+}
+
+#define NO_FUNC				(0)
+#define OTHER_FUNC			(1 << 0)
+#define MIN_AGG_FUNC		(1 << 1)
+#define MAX_AGG_FUNC		(1 << 2)
+#define COUNT_AGG_FUNC		(1 << 3)
+#define EVERY_AGG_FUNC		(1 << 4)
+#define BOOL_AND_AGG_FUNC	(1 << 5)
+#define BOOL_OR_AGG_FUNC	(1 << 6)
+
+#define EQ_COMPARISONS 		(bms_make_singleton(ROWCOMPARE_EQ))
+#define NE_COMPARISONS 		(bms_make_singleton(ROWCOMPARE_NE))
+#define LTE_COMPARISONS 	(bms_add_member(bms_make_singleton(ROWCOMPARE_LE), ROWCOMPARE_LT))
+#define GTE_COMPARISONS 	(bms_add_member(bms_make_singleton(ROWCOMPARE_GE), ROWCOMPARE_GT))
+
+#define MatchesOnly(a,b)	(((a) & (b)) && !((a) & (~(b))))
+#define CanOptimise(s) 		(!bms_is_empty(s) && \
+							(bms_is_subset(s, EQ_COMPARISONS)  || \
+							 bms_is_subset(s, NE_COMPARISONS)  || \
+							 bms_is_subset(s, LTE_COMPARISONS) || \
+							 bms_is_subset(s, GTE_COMPARISONS) ))
+
+
+// TODO review TODOs in the tests
+// TODO assertions should allow unknown according to the SQL specification
+// TODO traversal into views needs rethinking - dependencies?
+// TODO pg_dump support
+
+/*
+ * DML operations that could affect the truth of an assertion. Only
+ * INSERT and DELETE are considered as part of the labeling algorithm.
+ * UPDATEs are inferred using different logic.
+ */
+typedef enum DmlOp
+{
+	INSERT,
+	DELETE,
+	INSERT_DELETE
+} DmlOp;
+
+
+/*
+ * A context used to capture operations that may invalidate an assertion.
+ */
+typedef struct AssertionInfo
+{
+	DmlOp	label;         /* current invaliding operation */
+	Expr   *expr;          /* current Expression node */
+	List   *rtable;        /* current range tables */
+	List   *operators;     /* current operators */
+	SetOperation setOp;         /* current set-operation */
+	bool	invert;		   /* ... */
+	bool	inView;        /* if the walker has entered a view */
+	bool	inTargetEntry; /* if the walker has entered a TargetEntry node */
+	bool	inComparison;  /* if the walker has entered a comparison operation */
+	bool	inExists;      /* if the walker has entered an EXISTS node */
+
+	List   *dependencies; /* ... */
+	List   *relations;    /* relation Oids for all tables involved in the assertion check */
+	List   *inserts;      /* relation Oids for which INSERT could invalidate the assertion */
+	List   *deletes;      /* relation Oids for which DELETE could invalidate the assertion */
+	List   *updates;      /* relation Oids for which UPDATE could invalidate the assertion */
+	List   *columns;      /* list of ObjectAddresses referencing involved columns */
+} AssertionInfo;
+
+
+static void initAssertionInfo(AssertionInfo *info);
+static void copyAssertionInfo(AssertionInfo *target, AssertionInfo *source);
+static DmlOp oppositeDmlOp(DmlOp operation);
+static RowCompareType oppositeCompareType(RowCompareType type);
+static DmlOp labelForComparisonWithAggFuncs(DmlOp label, RowCompareType compOp, int aggFuncs);
+static int16 triggerOnEvents(AssertionInfo *info, Oid relationId);
+static List *triggerOnColumns(AssertionInfo *info, Oid relationId);
+static bool listContainsObjectAddress(List *list, ObjectAddress *address);
+static Bitmapset * strategiesForOperators(List *operators);
+static int functionsForTargetList(List *targetList);
+static int funcMaskForFuncOid(Oid funcOid);
+static Query * queryForSQLFunction(FuncExpr *funcExpr);
+
+/* Expression visiting */
+static bool visitAllNodes(Node *node, AssertionInfo *info);
+static bool visitRangeTblRef(RangeTblRef *node, AssertionInfo *info);
+static bool visitQuery(Query *node, AssertionInfo *info);
+static bool visitSetOperationStmt(SetOperationStmt *node, AssertionInfo *info);
+static bool visitBoolExpr(BoolExpr *node, AssertionInfo *info);
+static bool visitSubLink(SubLink *node, AssertionInfo *info);
+static bool visitFuncExpr(FuncExpr *node, AssertionInfo *info);
+static bool visitExpr(Expr *node, AssertionInfo *info);
+static bool visitVar(Var *node, AssertionInfo *info);
+
+/* TargetList visiting */
+static bool visitAggrefNodes(Node *node, int *aggFuncs);
+static bool visitAggref(Aggref *node, int *aggFuncs);
+static bool visitWindowFunc(WindowFunc *node, int *aggFuncs);
+
+
+static void
+initAssertionInfo(AssertionInfo *info)
+{
+	info->label = DELETE;
+	info->expr = NULL;
+	info->rtable = NIL;
+	info->operators = NIL;
+	info->setOp = SETOP_NONE;
+	info->invert = false;
+	info->inView = false;
+	info->inTargetEntry = false;
+	info->inComparison = false;
+	info->inExists = false;
+
+	info->dependencies = NIL;
+	info->relations = NIL;
+	info->inserts = NIL;
+	info->deletes = NIL;
+	info->updates = NIL;
+	info->columns = NIL;
+}
+
+
+static void
+copyAssertionInfo(AssertionInfo *target, AssertionInfo *source)
+{
+	target->label = source->label;
+	target->expr = source->expr;
+	target->rtable = source->rtable;
+	target->operators = source->operators;
+	target->setOp = source->setOp;
+	target->invert = source->invert;
+	target->inView = source->inView;
+	target->inTargetEntry = source->inTargetEntry;
+	target->inComparison = source->inComparison;
+	target->inExists = source->inExists;
+}
+
+
+static DmlOp
+oppositeDmlOp(DmlOp operation)
+{
+	switch (operation)
+	{
+		case INSERT:
+			return DELETE;
+		case DELETE:
+			return INSERT;
+		case INSERT_DELETE:
+			return INSERT_DELETE;
+	}
+}
+
+
+static RowCompareType
+oppositeCompareType(RowCompareType type)
+{
+	switch (type)
+	{
+		case ROWCOMPARE_LE:
+			return ROWCOMPARE_GE;
+		case ROWCOMPARE_LT:
+			return ROWCOMPARE_GT;
+		case ROWCOMPARE_GT:
+			return ROWCOMPARE_LT;
+		case ROWCOMPARE_GE:
+			return ROWCOMPARE_LE;
+		default:
+			return type; /* we do not flip EQ and NE comparisons */
+	}
+}
+
+
+static DmlOp
+labelForComparisonWithAggFuncs(DmlOp label, RowCompareType compOp, int aggFuncs)
+{
+	int stronger, weaker;
+
+	switch (compOp)
+	{
+		case ROWCOMPARE_LT:
+		case ROWCOMPARE_LE:
+			stronger = MIN_AGG_FUNC;
+			weaker = MAX_AGG_FUNC | COUNT_AGG_FUNC;
+			break;
+
+		case ROWCOMPARE_EQ:
+			stronger = BOOL_AND_AGG_FUNC | EVERY_AGG_FUNC;
+			weaker = BOOL_OR_AGG_FUNC;
+			break;
+
+		case ROWCOMPARE_NE:
+			stronger = BOOL_AND_AGG_FUNC | EVERY_AGG_FUNC;
+			weaker = BOOL_OR_AGG_FUNC;
+			break;
+
+		case ROWCOMPARE_GE:
+		case ROWCOMPARE_GT:
+			stronger = MAX_AGG_FUNC | COUNT_AGG_FUNC;
+			weaker = MIN_AGG_FUNC;
+			break;
+
+		default:
+			stronger = weaker = NO_FUNC;
+	}
+
+	if (MatchesOnly(aggFuncs, weaker))
+		return label;
+	else if (MatchesOnly(aggFuncs, stronger))
+		return oppositeDmlOp(label);
+	else
+		return INSERT_DELETE;
+}
+
+
+static int16
+triggerOnEvents(AssertionInfo *info, Oid relationId)
+{
+	int16 result = 0;
+	if (list_member_oid(info->inserts, relationId))
+		result |= TRIGGER_TYPE_INSERT;
+	if (list_member_oid(info->deletes, relationId))
+		result |= TRIGGER_TYPE_DELETE | TRIGGER_TYPE_TRUNCATE;
+	if (list_member_oid(info->updates, relationId))
+		result |= TRIGGER_TYPE_UPDATE;
+	return result;
+}
+
+
+/*
+ * Returns a list of string nodes, suitable for use in the trigger
+ * definition, that contain the column names to be triggered against
+ * on UPDATE operations.
+ */
+static List *
+triggerOnColumns(AssertionInfo *info, Oid relationId)
+{
+	List     	  *columns = NIL;
+	ListCell 	  *cell;
+
+	foreach(cell, info->columns)
+	{
+		ObjectAddress *column = (ObjectAddress *) lfirst(cell);
+		AttrNumber attrNumber = (AttrNumber) column->objectSubId;
+
+		if (column->objectId == relationId)
+		{
+			Value *name = makeString(get_attname(relationId, attrNumber, false));
+			columns = lappend(columns, name);
+		}
+	}
+
+	return columns;
+}
+
+
+static bool
+listContainsObjectAddress(List *list, ObjectAddress *address)
+{
+	ListCell 	  *cell;
+	ObjectAddress *item;
+
+	foreach(cell, list)
+	{
+		item = (ObjectAddress *) lfirst(cell);
+		if (item->classId == address->classId &&
+			item->objectId == address->objectId &&
+			item->objectSubId == address->objectSubId)
+			return true;
+	}
+
+	return false;
+}
+
+
+static Bitmapset *
+strategiesForOperators(List *operators)
+{
+	ListCell  *operatorCell;
+	Bitmapset *strategies = NULL;
+
+	foreach(operatorCell, operators)
+	{
+		Oid operator = lfirst_oid(operatorCell);
+		List *interpretations = get_op_btree_interpretation(operator);
+		ListCell *interpretationCell;
+
+		foreach(interpretationCell, interpretations)
+			strategies = bms_add_member(strategies,
+										((OpBtreeInterpretation *) lfirst(interpretationCell))->strategy);
+	}
+
+	return strategies;
+}
+
+
+static int
+functionsForTargetList(List *targetList)
+{
+	int functionMask = NO_FUNC;
+	expression_tree_walker((Node *) targetList, visitAggrefNodes, &functionMask);
+	return functionMask;
+}
+
+
+static int
+funcMaskForFuncOid(Oid funcOid)
+{
+	char *name = get_func_name(funcOid);
+
+	if (name == NULL)
+		return OTHER_FUNC;
+	else if (strncmp(name, "min", strlen("min")) == 0)
+		return MIN_AGG_FUNC;
+	else if (strncmp(name, "max", strlen("max")) == 0)
+		return MAX_AGG_FUNC;
+	else if (strncmp(name, "count", strlen("count")) == 0)
+		return COUNT_AGG_FUNC;
+	else if (strncmp(name, "every", strlen("every")) == 0)
+		return EVERY_AGG_FUNC;
+	else if (strncmp(name, "bool_and", strlen("bool_and")) == 0)
+		return BOOL_AND_AGG_FUNC;
+	else if (strncmp(name, "bool_or", strlen("bool_or")) == 0)
+		return BOOL_OR_AGG_FUNC;
+	else
+		return OTHER_FUNC;
+}
+
+
+static Query *
+queryForSQLFunction(FuncExpr *funcExpr)
+{
+	Oid			funcId;
+	Relation 	procRel;
+	HeapTuple	tuple;
+	Datum		datum;
+	bool		isNull;
+	char	   *sql;
+	List	   *rawParseTree;
+	ParseState *pstate;
+	Query	   *query;
+	SQLFunctionParseInfoPtr pinfo;
+
+	funcId = funcExpr->funcid;
+	procRel = heap_open(ProcedureRelationId, ShareLock);
+
+	tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcId));
+	if (!HeapTupleIsValid(tuple))
+		elog(ERROR, "cache lookup failed for function %u", funcId);
+
+	datum = SysCacheGetAttr(PROCOID,
+							tuple,
+							Anum_pg_proc_prosrc,
+							&isNull);
+	if (isNull)
+		elog(ERROR, "null prosrc for function %u", funcId);
+
+	sql = TextDatumGetCString(datum);
+	rawParseTree = pg_parse_query(sql);
+
+	pinfo = prepare_sql_fn_parse_info(tuple,
+									  (Node *) funcExpr,
+									  funcExpr->inputcollid);
+
+	pstate = make_parsestate(NULL);
+	pstate->p_sourcetext = sql;
+	sql_fn_parser_setup(pstate, pinfo);
+
+	query = transformTopLevelStmt(pstate, linitial(rawParseTree));
+	free_parsestate(pstate);
+
+	ReleaseSysCache(tuple);
+	heap_close(procRel, NoLock);
+
+	return query;
+}
+
+
+static bool
+visitRangeTblRef(RangeTblRef *node, AssertionInfo *info)
+{
+	RangeTblEntry  *entry;
+	Oid				relationId;
+	RTEKind			rtekind;
+	char 		    relkind;
+	bool			result;
+
+	entry = rt_fetch(node->rtindex, info->rtable);
+	rtekind = entry->rtekind;
+	result = false;
+
+	if (rtekind == RTE_RELATION)
+	{
+		relationId = getrelid(node->rtindex, info->rtable);
+		relkind = get_rel_relkind(relationId);
+
+		if (relkind == RELKIND_RELATION)
+		{
+			if (info->label == INSERT || info->label == INSERT_DELETE)
+				info->inserts = list_append_unique_oid(info->inserts, relationId);
+
+			if (info->label == DELETE || info->label == INSERT_DELETE)
+				info->deletes = list_append_unique_oid(info->deletes, relationId);
+
+			if (!info->inView)
+				info->dependencies = list_append_unique_oid(info->dependencies, relationId);
+
+			info->relations = list_append_unique_oid(info->relations, relationId);
+
+		}
+		else if (relkind == RELKIND_VIEW)
+		{
+			Relation view = heap_open(relationId, AccessShareLock);
+			Query *query = get_view_query(view);
+
+			if (!info->inView)
+				info->dependencies = list_append_unique_oid(info->dependencies, relationId);
+
+			info->inView = true;
+			result = visitQuery(query, info);
+
+			heap_close(view, NoLock);
+		}
+
+	}
+	else if (rtekind == RTE_TABLEFUNC)
+	{
+		result = visitAllNodes((Node *) entry->tablefunc, info);
+	}
+	else if (rtekind == RTE_FUNCTION)
+	{
+		result = visitAllNodes((Node *) entry->functions, info);
+	}
+	else if (rtekind == RTE_SUBQUERY)
+	{
+		result = visitQuery(entry->subquery, info);
+	}
+
+	return result;
+}
+
+
+static bool
+visitQuery(Query *node, AssertionInfo *info)
+{
+	info->rtable = node->rtable;
+
+	if (info->inComparison)
+	{
+		int functions = functionsForTargetList(node->targetList);
+		Bitmapset *strategies = strategiesForOperators(info->operators);
+
+		if (CanOptimise(strategies))
+		{
+			RowCompareType rowCompareType = (RowCompareType) bms_first_member(strategies);
+			info->label = labelForComparisonWithAggFuncs(
+				info->label,
+				info->invert ? oppositeCompareType(rowCompareType) : rowCompareType,
+				functions
+			);
+		}
+		else
+		{
+			/*
+			 * Either no btree interpretation was found for the operator(s), there were
+			 * multiple interpretations that were incompatible with each other, or the
+			 * found interpretations were not able to be optimised. We must therefore
+			 * assume that both INSERT and DELETE operations may be invalidating.
+			 */
+			info->label = INSERT_DELETE;
+		}
+	}
+	else if (node->hasWindowFuncs)
+	{
+		info->label = INSERT_DELETE;
+	}
+
+	return query_tree_walker(node,
+							 visitAllNodes,
+							 info,
+							 QTW_IGNORE_RANGE_TABLE);
+}
+
+
+static bool
+visitSetOperationStmt(SetOperationStmt *node, AssertionInfo *info)
+{
+	info->setOp = node->op;
+
+	if (visitAllNodes(node->larg, info))
+		return true;
+
+	if (info->setOp == SETOP_EXCEPT)
+		info->label = oppositeDmlOp(info->label);
+
+	return visitAllNodes(node->rarg, info);
+}
+
+
+static bool
+visitBoolExpr(BoolExpr *node, AssertionInfo *info)
+{
+	if (node->boolop == NOT_EXPR)
+		info->label = oppositeDmlOp(info->label);
+
+	return expression_tree_walker((Node *) node, visitAllNodes, (void *) info);
+}
+
+
+// TODO refactor this function
+static bool
+visitSubLink(SubLink *node, AssertionInfo *info)
+{
+	List *operators;
+	bool  invert;
+	bool  inComparison;
+	bool  inExists;
+
+	switch (node->subLinkType)
+	{
+		case ARRAY_SUBLINK: // TODO write tests for this
+		case EXPR_SUBLINK:
+		{
+			Expr *expr = info->expr;
+			bool hasExpr = (expr != NULL);
+
+			if (hasExpr && IsA(expr, OpExpr))
+			{
+				OpExpr *opExpr = (OpExpr *) expr;
+				inComparison = true;
+				inExists = false;
+
+				/*
+				 * Optimisation code is written under the assumption that the sub-select is the
+				 * right operand. If it is the left operand the comparison needs to be inverted.
+				 */
+				invert = (list_nth_node(SubLink, opExpr->args, 0) == node);
+				operators = list_make1_oid(opExpr->opno);
+			}
+			else if (hasExpr && IsA(expr, FuncExpr) &&
+					((FuncExpr *)expr)->funcresulttype == BOOLOID)
+			{
+				/*
+				 * We are inside a function invocation that returns Boolean but is not an OpExpr.
+				 * Let's exploit the fact that "expr == TRUE -> expr", and pretend there is an
+				 * equality operator.
+				 */
+				inComparison = true;
+				inExists = false;
+				operators = list_make1_oid(F_BOOLEQ);
+				invert = false;
+			}
+			else if (exprType((const Node *) node) == BOOLOID)
+			{
+				/*
+				 * We are _not_ inside either an OpExpr or FuncExpr, but we are a query that can be
+				 * coerced to Boolean. We use the same logic above e.g. "expr == TRUE -> expr"
+				 */
+				inComparison = true;
+				inExists = false;
+				operators = list_make1_oid(F_BOOLEQ);
+				invert = false;
+			}
+			else
+			{
+				inComparison = false;
+				inExists = false;
+				invert = false;
+				operators = NIL;
+			}
+		}
+		break;
+
+		case ALL_SUBLINK:
+		case ANY_SUBLINK:
+		case ROWCOMPARE_SUBLINK:
+		{
+			if (IsA(node->testexpr, OpExpr))
+			{
+				OpExpr *expr = (OpExpr *) node->testexpr;
+				inComparison = true;
+				inExists = false;
+				invert = false;
+				operators = list_make1_oid(expr->opno);
+			}
+			else if (IsA(node->testexpr, RowCompareExpr))
+			{
+				RowCompareExpr *expr = (RowCompareExpr *) node->testexpr;
+				inComparison = true;
+				inExists = false;
+				invert = false;
+				operators = list_copy(expr->opnos);
+			}
+			else
+			{
+				inComparison = false;
+				inExists = false;
+				invert = false;
+				operators = NIL;
+			}
+		}
+		break;
+
+		case EXISTS_SUBLINK:
+		{
+			/* existential quantification, no operators */
+			inComparison = false;
+			inExists = true;
+			invert = false;
+			operators = NIL;
+		}
+		break;
+			// case MULTIEXPR_SUBLINK: // TODO write tests for MULTIEXPR_SUBLINK? -- or, can it only occur in UPDATEs?
+		default:
+		{
+			elog(ERROR, "unhandled sublink type %u", node->subLinkType);
+			return true;
+		}
+
+	}
+
+	info->operators = operators;
+	info->invert = invert;
+	info->inComparison = inComparison;
+	info->inExists = inExists;
+	info->setOp = SETOP_NONE;
+
+	return expression_tree_walker((Node *) node, visitAllNodes, (void *) info);
+}
+
+
+static bool
+visitTargetEntry(TargetEntry *node, AssertionInfo *info)
+{
+	info->inTargetEntry = true;
+	return expression_tree_walker((Node *) node, visitAllNodes, (void *) info);
+}
+
+
+static bool
+visitFromExpr(FromExpr *node, AssertionInfo *info)
+{
+	info->inExists = false;
+	info->inComparison = false;
+	return expression_tree_walker((Node *) node, visitAllNodes, (void *) info);
+}
+
+
+static bool
+visitFuncExpr(FuncExpr *node, AssertionInfo *info)
+{
+	Oid lang = get_func_lang(node->funcid);
+
+	info->expr = (Expr *) node;
+
+	if (!(lang == INTERNALlanguageId || lang == SQLlanguageId))
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_AMBIGUOUS_FUNCTION),
+				 errmsg("function \"%s\" uses unsupported language \"%s\"",
+				   get_func_name(node->funcid), get_language_name(lang, false))));
+		return true;
+	}
+
+	if (expression_tree_walker((Node *) node, visitAllNodes, (void *) info))
+		return true;
+
+	if (lang == SQLlanguageId)
+	{
+		Query *query = queryForSQLFunction(node);
+		Node *next;
+		if (node->funcretset)
+			next = (Node *) query;
+		else
+			next = (Node *) ((TargetEntry *) linitial(query->targetList))->expr;
+
+		return visitAllNodes(next, info);
+	}
+
+	return false;
+}
+
+
+static bool
+visitExpr(Expr *node, AssertionInfo *info)
+{
+	info->expr = node;
+	return expression_tree_walker((Node *) node, visitAllNodes, (void *) info);
+}
+
+
+static bool
+visitVar(Var *node, AssertionInfo *info)
+{
+	RangeTblEntry *entry = rt_fetch(node->varno, info->rtable);
+
+	// TODO we should do this only for Tables and not Views?
+	// TODO optimisations for set-operations
+	if (entry->rtekind == RTE_RELATION && !(info->inExists && info->setOp == SETOP_NONE))
+	{
+		Oid relationId = getrelid(node->varno, info->rtable);
+		ObjectAddress *column = (ObjectAddress *) palloc(sizeof(ObjectAddress));
+
+		column->classId = RelationRelationId;
+		column->objectId = relationId;
+		column->objectSubId = node->varattno;
+
+		if (!listContainsObjectAddress(info->columns, column))
+			info->columns = lcons(column, info->columns);
+
+		info->relations = list_append_unique_oid(info->relations, relationId);
+		info->updates = list_append_unique_oid(info->updates, relationId);
+	}
+
+	return expression_tree_walker((Node *) node, visitAllNodes, (void *) info);
+}
+
+
+static bool
+visitAllNodes(Node *node, AssertionInfo *info)
+{
+	AssertionInfo stored;
+	bool result;
+
+	copyAssertionInfo(&stored, info);
+
+	if (node == NULL)
+		result = false;
+	else if (IsA(node, RangeTblRef))
+		result = visitRangeTblRef((RangeTblRef *) node, info);
+	else if (IsA(node, Query))
+		result = visitQuery((Query *) node, info);
+	else if (IsA(node, BoolExpr))
+		result = visitBoolExpr((BoolExpr *) node, info);
+	else if (IsA(node, SubLink))
+		result = visitSubLink((SubLink *) node, info);
+	else if (IsA(node, SetOperationStmt))
+		result = visitSetOperationStmt((SetOperationStmt *) node, info);
+	else if (IsA(node, FuncExpr))
+		result = visitFuncExpr((FuncExpr *) node, info);
+	else if (IsA(node, OpExpr) ||
+			 IsA(node, DistinctExpr) ||
+			 IsA(node, NullIfExpr))
+		result = visitExpr((Expr *) node, info);
+	else if (IsA(node, TargetEntry))
+		result = visitTargetEntry((TargetEntry *) node, info);
+	else if (IsA(node, Var))
+		result = visitVar((Var *) node, info);
+	else if (IsA(node, FromExpr))
+		result = visitFromExpr((FromExpr *) node, info);
+	else
+		result = expression_tree_walker(node, visitAllNodes, (void *) info);
+
+	copyAssertionInfo(info, &stored);
+
+	return result;
+}
+
+
+static bool
+visitAggrefNodes(Node *node, int *aggFuncs)
+{
+	if (node == NULL)
+		return false;
+	else if (IsA(node, Aggref))
+		return visitAggref((Aggref *) node, aggFuncs);
+	else if(IsA(node, WindowFunc))
+		return visitWindowFunc((WindowFunc *) node, aggFuncs);
+	else
+		return expression_tree_walker(node, visitAggrefNodes, (void *) aggFuncs);
+}
+
+
+static bool
+visitAggref(Aggref *node, int *aggFuncs)
+{
+	*aggFuncs |= funcMaskForFuncOid(node->aggfnoid);
+	return expression_tree_walker((Node *) node, visitAggrefNodes, (void *) aggFuncs);
+}
+
+
+static bool
+visitWindowFunc(WindowFunc *node, int *aggFuncs)
+{
+	*aggFuncs |= funcMaskForFuncOid(node->winfnoid);
+
+	return expression_tree_walker((Node *) node, visitAggrefNodes, (void *) aggFuncs);
+}
+
+
+ObjectAddress
+CreateAssertion(CreateAssertionStmt *stmt)
+{
+	Oid namespaceId;
+	char *assertion_name;
+	AclResult aclresult;
+	Node *expr;
+	ParseState *pstate;
+	char *ccsrc;
+	char *ccbin;
+	Oid constrOid;
+	AssertionInfo info;
+	ListCell *lc;
+	ObjectAddress address;
+
+	namespaceId = QualifiedNameGetCreationNamespace(stmt->assertion_name,
+													&assertion_name);
+
+	aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(), ACL_CREATE);
+	if (aclresult != ACLCHECK_OK)
+		aclcheck_error(aclresult, OBJECT_SCHEMA,
+					   get_namespace_name(namespaceId));
+
+	if (ConstraintNameIsUsed(CONSTRAINT_ASSERTION, InvalidOid, namespaceId, assertion_name))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_NAME),
+				 errmsg("assertion \"%s\" already exists", assertion_name)));
+
+	pstate = make_parsestate(NULL);
+	expr = transformExpr(pstate, stmt->constraint->raw_expr, EXPR_KIND_ASSERTION_CHECK);
+	expr = coerce_to_boolean(pstate, expr, "CHECK");
+
+	ccbin = nodeToString(expr);
+	ccsrc = deparse_expression(expr, NIL, false, false);
+
+	constrOid = CreateConstraintEntry(assertion_name,
+									  namespaceId,
+									  CONSTRAINT_CHECK, /* constraint type */
+									  stmt->constraint->deferrable,
+									  stmt->constraint->initdeferred,
+									  !stmt->constraint->skip_validation,
+									  InvalidOid, /* not a relation constraint */
+									  NULL,          /* no keys */
+									  0,          /* no keys */
+									  InvalidOid, /* not a domain constraint */
+									  InvalidOid, /* no associated index */
+									  InvalidOid, /* foreign key fields ... */
+									  NULL,
+									  NULL,
+									  NULL,
+									  NULL,
+									  0,
+									  ' ',
+									  ' ',
+									  ' ',
+									  NULL,    /* not an exclusion constraint */
+									  expr, /* tree form of check constraint */
+									  ccbin, /* binary form of check constraint */
+									  ccsrc, /* source form of check constraint */
+									  true, /* is local */
+									  0,   /* inhcount */
+									  false, /* noinherit XXX */
+									  false); /* is_internal */
+
+	initAssertionInfo(&info);
+	visitAllNodes(expr, &info);
+
+	foreach (lc, info.relations)
+	{
+		Oid relationId = lfirst_oid(lc);
+		CreateTrigStmt *trigger;
+		Relation rel;
+
+		rel = heap_open(relationId, ShareLock); // XXX
+
+		trigger = makeNode(CreateTrigStmt);
+		trigger->trigname = "AssertionTrigger";
+		trigger->relation = makeRangeVar(get_namespace_name(namespaceId),
+										 pstrdup(RelationGetRelationName(rel)),
+										 -1);
+		trigger->funcname = SystemFuncName("assertion_check");
+		trigger->args = NIL;
+		trigger->row = false;
+		trigger->timing = TRIGGER_TYPE_AFTER;
+		trigger->events = triggerOnEvents(&info, relationId);
+		trigger->columns = triggerOnColumns(&info, relationId);
+		trigger->whenClause = NULL;
+		trigger->isconstraint = true;
+		trigger->deferrable = stmt->constraint->deferrable;
+		trigger->initdeferred = stmt->constraint->initdeferred;
+		trigger->constrrel = NULL;
+
+		CreateTrigger(trigger, NULL, InvalidOid, relationId, constrOid, InvalidOid, true);
+
+		heap_close(rel, NoLock);
+	}
+
+	/*
+	 * Record dependencies between the constraint and the relations found in the
+	 * top-level expression. Dependencies to specific columns will already have
+	 * been recorded by the trigger creation.
+	 */
+	ObjectAddress myself, referenced;
+	ListCell *cell;
+
+	myself.classId = ConstraintRelationId;
+	myself.objectId = constrOid;
+	myself.objectSubId = 0;
+
+	foreach (cell, info.dependencies)
+	{
+		referenced.classId = RelationRelationId;
+		referenced.objectId = lfirst_oid(cell);
+		referenced.objectSubId = 0;
+		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+	}
+
+	test_assertion_expr(assertion_name, ccsrc);
+
+	ObjectAddressSet(address, ConstraintRelationId, constrOid);
+
+	return address;
+}
+
+
+ObjectAddress
+RenameAssertion(RenameStmt *stmt)
+{
+	Oid           assertionOid;
+	ObjectAddress address;
+	Relation      rel;
+	HeapTuple     tuple;
+	Form_pg_constraint con;
+	AclResult     aclresult;
+
+	List *oldName = castNode(List, stmt->object);
+	char *newName = stmt->newname;
+
+	rel = heap_open(ConstraintRelationId, RowExclusiveLock);
+	assertionOid = get_assertion_oid(oldName, false);
+
+	tuple = SearchSysCache1(CONSTROID, ObjectIdGetDatum(assertionOid));
+	if (!HeapTupleIsValid(tuple))
+		elog(ERROR, "cache lookup failed for constraint %u",
+			 assertionOid);
+	con = (Form_pg_constraint) GETSTRUCT(tuple);
+
+	if (!pg_constraint_ownercheck(assertionOid, GetUserId()))
+		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_CONVERSION,
+					   NameListToString(oldName));
+
+	aclresult = pg_namespace_aclcheck(con->connamespace, GetUserId(), ACL_CREATE);
+	if (aclresult != ACLCHECK_OK)
+		aclcheck_error(aclresult, OBJECT_SCHEMA,
+					   get_namespace_name(con->connamespace));
+
+	ReleaseSysCache(tuple);
+	RenameConstraintById(assertionOid, newName);
+	ObjectAddressSet(address, ConstraintRelationId, assertionOid);
+	heap_close(rel, NoLock);
+
+	return address;
+}
diff --git a/src/backend/commands/event_trigger.c b/src/backend/commands/event_trigger.c
index 549c7ea51d..95e6a6687d 100644
--- a/src/backend/commands/event_trigger.c
+++ b/src/backend/commands/event_trigger.c
@@ -88,6 +88,7 @@ typedef enum
 static event_trigger_support_data event_trigger_support[] = {
 	{"ACCESS METHOD", true},
 	{"AGGREGATE", true},
+	{"ASSERTION", true},
 	{"CAST", true},
 	{"CONSTRAINT", true},
 	{"COLLATION", true},
@@ -1081,6 +1082,7 @@ EventTriggerSupportsObjectType(ObjectType obtype)
 			return false;
 		case OBJECT_ACCESS_METHOD:
 		case OBJECT_AGGREGATE:
+		case OBJECT_ASSERTION:
 		case OBJECT_AMOP:
 		case OBJECT_AMPROC:
 		case OBJECT_ATTRIBUTE:
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 3ad4da64aa..0bbb8bb87a 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -4320,6 +4320,17 @@ _copyCreateSchemaStmt(const CreateSchemaStmt *from)
 	return newnode;
 }
 
+static CreateAssertionStmt *
+_copyCreateAssertionStmt(const CreateAssertionStmt *from)
+{
+	CreateAssertionStmt *newnode = makeNode(CreateAssertionStmt);
+
+	COPY_NODE_FIELD(assertion_name);
+	COPY_NODE_FIELD(constraint);
+
+	return newnode;
+}
+
 static CreateConversionStmt *
 _copyCreateConversionStmt(const CreateConversionStmt *from)
 {
@@ -5389,6 +5400,9 @@ copyObjectImpl(const void *from)
 		case T_CreateSchemaStmt:
 			retval = _copyCreateSchemaStmt(from);
 			break;
+		case T_CreateAssertionStmt:
+			retval = _copyCreateAssertionStmt(from);
+			break;
 		case T_CreateConversionStmt:
 			retval = _copyCreateConversionStmt(from);
 			break;
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 765b1be74b..9ac7971b0c 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -2121,6 +2121,15 @@ _equalCreateSchemaStmt(const CreateSchemaStmt *a, const CreateSchemaStmt *b)
 	return true;
 }
 
+static bool
+_equalCreateAssertionStmt(const CreateAssertionStmt *a, const CreateAssertionStmt *b)
+{
+	COMPARE_NODE_FIELD(assertion_name);
+	COMPARE_NODE_FIELD(constraint);
+
+	return true;
+}
+
 static bool
 _equalCreateConversionStmt(const CreateConversionStmt *a, const CreateConversionStmt *b)
 {
@@ -3521,6 +3530,9 @@ equal(const void *a, const void *b)
 		case T_CreateSchemaStmt:
 			retval = _equalCreateSchemaStmt(a, b);
 			break;
+		case T_CreateAssertionStmt:
+			retval = _equalCreateAssertionStmt(a, b);
+			break;
 		case T_CreateConversionStmt:
 			retval = _equalCreateConversionStmt(a, b);
 			break;
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index cd5ba2d4d8..22926ff03a 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -259,11 +259,11 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 		CreateOpFamilyStmt AlterOpFamilyStmt CreatePLangStmt
 		CreateSchemaStmt CreateSeqStmt CreateStmt CreateStatsStmt CreateTableSpaceStmt
 		CreateFdwStmt CreateForeignServerStmt CreateForeignTableStmt
-		CreateAssertStmt CreateTransformStmt CreateTrigStmt CreateEventTrigStmt
+		CreateAssertionStmt CreateTransformStmt CreateTrigStmt CreateEventTrigStmt
 		CreateUserStmt CreateUserMappingStmt CreateRoleStmt CreatePolicyStmt
 		CreatedbStmt DeclareCursorStmt DefineStmt DeleteStmt DiscardStmt DoStmt
 		DropOpClassStmt DropOpFamilyStmt DropPLangStmt DropStmt
-		DropAssertStmt DropCastStmt DropRoleStmt
+		DropCastStmt DropRoleStmt
 		DropdbStmt DropTableSpaceStmt
 		DropTransformStmt
 		DropUserMappingStmt ExplainStmt FetchStmt
@@ -859,7 +859,7 @@ stmt :
 			| CopyStmt
 			| CreateAmStmt
 			| CreateAsStmt
-			| CreateAssertStmt
+			| CreateAssertionStmt
 			| CreateCastStmt
 			| CreateConversionStmt
 			| CreateDomainStmt
@@ -895,7 +895,6 @@ stmt :
 			| DeleteStmt
 			| DiscardStmt
 			| DoStmt
-			| DropAssertStmt
 			| DropCastStmt
 			| DropOpClassStmt
 			| DropOpFamilyStmt
@@ -5624,45 +5623,28 @@ enable_trigger:
  *
  *		QUERIES :
  *				CREATE ASSERTION ...
- *				DROP ASSERTION ...
  *
  *****************************************************************************/
 
-CreateAssertStmt:
-			CREATE ASSERTION name CHECK '(' a_expr ')'
+CreateAssertionStmt:
+			CREATE ASSERTION any_name CHECK '(' a_expr ')'
 			ConstraintAttributeSpec
 				{
-					CreateTrigStmt *n = makeNode(CreateTrigStmt);
-					n->trigname = $3;
-					n->args = list_make1($6);
-					n->isconstraint  = true;
-					processCASbits($8, @8, "ASSERTION",
-								   &n->deferrable, &n->initdeferred, NULL,
-								   NULL, yyscanner);
-
-					ereport(ERROR,
-							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-							 errmsg("CREATE ASSERTION is not yet implemented")));
-
-					$$ = (Node *)n;
-				}
-		;
-
-DropAssertStmt:
-			DROP ASSERTION name opt_drop_behavior
-				{
-					DropStmt *n = makeNode(DropStmt);
-					n->objects = NIL;
-					n->behavior = $4;
-					n->removeType = OBJECT_TRIGGER; /* XXX */
-					ereport(ERROR,
-							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-							 errmsg("DROP ASSERTION is not yet implemented")));
-					$$ = (Node *) n;
+					CreateAssertionStmt *n = makeNode(CreateAssertionStmt);
+					Constraint *c = makeNode(Constraint);
+					c->contype = CONSTR_CHECK;
+					c->location = @4;
+					c->raw_expr = $6;
+					c->cooked_expr = NULL;
+ 					processCASbits($8, @8, "ASSERTION",
+								   &c->deferrable, &c->initdeferred, NULL,
+ 								   NULL, yyscanner);
+					n->assertion_name = $3;
+					n->constraint = c;
+ 					$$ = (Node *)n;
 				}
 		;
 
-
 /*****************************************************************************
  *
  *		QUERY :
@@ -6316,6 +6298,7 @@ drop_type_any_name:
 			| MATERIALIZED VIEW						{ $$ = OBJECT_MATVIEW; }
 			| INDEX									{ $$ = OBJECT_INDEX; }
 			| FOREIGN TABLE							{ $$ = OBJECT_FOREIGN_TABLE; }
+			| ASSERTION								{ $$ = OBJECT_ASSERTION; }
 			| COLLATION								{ $$ = OBJECT_COLLATION; }
 			| CONVERSION_P							{ $$ = OBJECT_CONVERSION; }
 			| STATISTICS							{ $$ = OBJECT_STATISTIC_EXT; }
@@ -6585,6 +6568,7 @@ comment_type_any_name:
 			| TABLE								{ $$ = OBJECT_TABLE; }
 			| VIEW								{ $$ = OBJECT_VIEW; }
 			| MATERIALIZED VIEW					{ $$ = OBJECT_MATVIEW; }
+			| ASSERTION							{ $$ = OBJECT_ASSERTION; }
 			| COLLATION							{ $$ = OBJECT_COLLATION; }
 			| CONVERSION_P						{ $$ = OBJECT_CONVERSION; }
 			| FOREIGN TABLE						{ $$ = OBJECT_FOREIGN_TABLE; }
@@ -8437,6 +8421,15 @@ RenameStmt: ALTER AGGREGATE aggregate_with_argtypes RENAME TO name
 					n->missing_ok = false;
 					$$ = (Node *)n;
 				}
+			| ALTER ASSERTION any_name RENAME TO name
+				{
+					RenameStmt *n = makeNode(RenameStmt);
+					n->renameType = OBJECT_ASSERTION;
+					n->object = (Node *) $3;
+					n->newname = $6;
+					n->missing_ok = false;
+					$$ = (Node *)n;
+				}
 			| ALTER COLLATION any_name RENAME TO name
 				{
 					RenameStmt *n = makeNode(RenameStmt);
@@ -9021,6 +9014,15 @@ AlterObjectSchemaStmt:
 					n->missing_ok = false;
 					$$ = (Node *)n;
 				}
+			| ALTER ASSERTION any_name SET SCHEMA name
+				{
+					AlterObjectSchemaStmt *n = makeNode(AlterObjectSchemaStmt);
+					n->objectType = OBJECT_ASSERTION;
+					n->object = (Node *) $3;
+					n->newschema = $6;
+					n->missing_ok = false;
+					$$ = (Node *)n;
+				}
 			| ALTER COLLATION any_name SET SCHEMA name
 				{
 					AlterObjectSchemaStmt *n = makeNode(AlterObjectSchemaStmt);
@@ -9306,6 +9308,14 @@ AlterOwnerStmt: ALTER AGGREGATE aggregate_with_argtypes OWNER TO RoleSpec
 					n->newowner = $6;
 					$$ = (Node *)n;
 				}
+			| ALTER ASSERTION any_name OWNER TO RoleSpec
+				{
+					AlterOwnerStmt *n = makeNode(AlterOwnerStmt);
+					n->objectType = OBJECT_ASSERTION;
+					n->object = (Node *) $3;
+					n->newowner = $6;
+					$$ = (Node *)n;
+				}
 			| ALTER COLLATION any_name OWNER TO RoleSpec
 				{
 					AlterOwnerStmt *n = makeNode(AlterOwnerStmt);
diff --git a/src/backend/parser/parse_agg.c b/src/backend/parser/parse_agg.c
index 377a7ed6d0..223cea1134 100644
--- a/src/backend/parser/parse_agg.c
+++ b/src/backend/parser/parse_agg.c
@@ -457,6 +457,7 @@ check_agglevels_and_constraints(ParseState *pstate, Node *expr)
 			break;
 		case EXPR_KIND_CHECK_CONSTRAINT:
 		case EXPR_KIND_DOMAIN_CHECK:
+		case EXPR_KIND_ASSERTION_CHECK:
 			if (isAgg)
 				err = _("aggregate functions are not allowed in check constraints");
 			else
@@ -875,6 +876,7 @@ transformWindowFuncCall(ParseState *pstate, WindowFunc *wfunc,
 			break;
 		case EXPR_KIND_CHECK_CONSTRAINT:
 		case EXPR_KIND_DOMAIN_CHECK:
+		case EXPR_KIND_ASSERTION_CHECK:
 			err = _("window functions are not allowed in check constraints");
 			break;
 		case EXPR_KIND_COLUMN_DEFAULT:
diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index 385e54a9b6..1933a615bf 100644
--- a/src/backend/parser/parse_expr.c
+++ b/src/backend/parser/parse_expr.c
@@ -1818,6 +1818,7 @@ transformSubLink(ParseState *pstate, SubLink *sublink)
 		case EXPR_KIND_RETURNING:
 		case EXPR_KIND_VALUES:
 		case EXPR_KIND_VALUES_SINGLE:
+		case EXPR_KIND_ASSERTION_CHECK:
 			/* okay */
 			break;
 		case EXPR_KIND_CHECK_CONSTRAINT:
@@ -3457,6 +3458,7 @@ ParseExprKindName(ParseExprKind exprKind)
 			return "VALUES";
 		case EXPR_KIND_CHECK_CONSTRAINT:
 		case EXPR_KIND_DOMAIN_CHECK:
+		case EXPR_KIND_ASSERTION_CHECK:
 			return "CHECK";
 		case EXPR_KIND_COLUMN_DEFAULT:
 		case EXPR_KIND_FUNCTION_DEFAULT:
diff --git a/src/backend/parser/parse_func.c b/src/backend/parser/parse_func.c
index ea5d5212b4..8193b7da37 100644
--- a/src/backend/parser/parse_func.c
+++ b/src/backend/parser/parse_func.c
@@ -2277,6 +2277,10 @@ check_srf_call_placement(ParseState *pstate, Node *last_srf, int location)
 			/* okay, since we process this like a SELECT tlist */
 			pstate->p_hasTargetSRFs = true;
 			break;
+		case EXPR_KIND_ASSERTION_CHECK:
+			/* okay */
+			pstate->p_hasTargetSRFs = true;
+			break;
 		case EXPR_KIND_CHECK_CONSTRAINT:
 		case EXPR_KIND_DOMAIN_CHECK:
 			err = _("set-returning functions are not allowed in check constraints");
diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c
index ed55521a0c..9ead34af3d 100644
--- a/src/backend/tcop/utility.c
+++ b/src/backend/tcop/utility.c
@@ -30,6 +30,7 @@
 #include "commands/cluster.h"
 #include "commands/comment.h"
 #include "commands/collationcmds.h"
+#include "commands/constraint.h"
 #include "commands/conversioncmds.h"
 #include "commands/copy.h"
 #include "commands/createas.h"
@@ -160,6 +161,7 @@ check_xact_readonly(Node *parsetree)
 		case T_RenameStmt:
 		case T_CommentStmt:
 		case T_DefineStmt:
+		case T_CreateAssertionStmt:
 		case T_CreateCastStmt:
 		case T_CreateEventTrigStmt:
 		case T_AlterEventTrigStmt:
@@ -1503,6 +1505,10 @@ ProcessUtilitySlow(ParseState *pstate,
 				address = DefineDomain((CreateDomainStmt *) parsetree);
 				break;
 
+			case T_CreateAssertionStmt:
+				address = CreateAssertion((CreateAssertionStmt *) parsetree);
+				break;
+
 			case T_CreateConversionStmt:
 				address = CreateConversionCommand((CreateConversionStmt *) parsetree);
 				break;
@@ -1913,6 +1919,9 @@ AlterObjectTypeCommandTag(ObjectType objtype)
 		case OBJECT_AGGREGATE:
 			tag = "ALTER AGGREGATE";
 			break;
+		case OBJECT_ASSERTION:
+			tag = "ALTER ASSERTION";
+			break;
 		case OBJECT_ATTRIBUTE:
 			tag = "ALTER TYPE";
 			break;
@@ -2251,6 +2260,9 @@ CreateCommandTag(Node *parsetree)
 				case OBJECT_DOMAIN:
 					tag = "DROP DOMAIN";
 					break;
+				case OBJECT_ASSERTION:
+					tag = "DROP ASSERTION";
+					break;
 				case OBJECT_COLLATION:
 					tag = "DROP COLLATION";
 					break;
@@ -2681,6 +2693,10 @@ CreateCommandTag(Node *parsetree)
 			tag = "REINDEX";
 			break;
 
+		case T_CreateAssertionStmt:
+			tag = "CREATE ASSERTION";
+			break;
+
 		case T_CreateConversionStmt:
 			tag = "CREATE CONVERSION";
 			break;
@@ -3281,6 +3297,10 @@ GetCommandLogLevel(Node *parsetree)
 			lev = LOGSTMT_ALL;	/* should this be DDL? */
 			break;
 
+		case T_CreateAssertionStmt:
+			lev = LOGSTMT_DDL;
+			break;
+
 		case T_CreateConversionStmt:
 			lev = LOGSTMT_DDL;
 			break;
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index bba595ad1d..6a0d6edb81 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -1542,6 +1542,25 @@ get_func_retset(Oid funcid)
 	return result;
 }
 
+/*
+ * get_func_lang
+ *		Given procedure id, return the function's language id.
+ */
+Oid
+get_func_lang(Oid funcid)
+{
+	HeapTuple	tp;
+	Oid			result;
+
+	tp = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
+	if (!HeapTupleIsValid(tp))
+		elog(ERROR, "cache lookup failed for function %u", funcid);
+
+	result = ((Form_pg_proc) GETSTRUCT(tp))->prolang;
+	ReleaseSysCache(tp);
+	return result;
+}
+
 /*
  * func_strict
  *		Given procedure id, return the function's proisstrict flag.
diff --git a/src/bin/psql/command.c b/src/bin/psql/command.c
index 3560318749..2635b280de 100644
--- a/src/bin/psql/command.c
+++ b/src/bin/psql/command.c
@@ -785,6 +785,9 @@ exec_command_d(PsqlScanState scan_state, bool active_branch, const char *cmd)
 			case 'p':
 				success = permissionsList(pattern);
 				break;
+			case 'Q':
+				success = describeAssertions(pattern);
+				break;
 			case 'T':
 				success = describeTypes(pattern, show_verbose, show_system);
 				break;
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index 0c3be1f504..762de44ff6 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -140,6 +140,66 @@ describeAggregates(const char *pattern, bool verbose, bool showSystem)
 	return true;
 }
 
+/* \dA
+ * Takes an optional regexp to select particular assertions
+ */
+bool
+describeAssertions(const char *pattern)
+{
+	PQExpBufferData buf;
+	PGresult   *res;
+	printQueryOpt myopt = pset.popt;
+
+	if (pset.sversion < 90400)
+	{
+		fprintf(stderr, _("The server (version %d.%d) does not support assertions.\n"),
+				pset.sversion / 10000, (pset.sversion / 100) % 100);
+		return true;
+	}
+
+	initPQExpBuffer(&buf);
+
+	printfPQExpBuffer(&buf,
+					  "SELECT n.nspname AS \"%s\",\n"
+							  "  c.conname AS \"%s\",\n"
+							  "  pg_catalog.pg_get_constraintdef(c.oid, true) AS \"%s\",\n"
+							  "  pg_catalog.obj_description(c.oid, 'pg_constraint') AS \"%s\"\n"
+							  "FROM pg_catalog.pg_constraint c\n"
+							  "     LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.connamespace\n"
+							  "WHERE c.conrelid = 0 AND c.contypid = 0\n",
+					  gettext_noop("Schema"),
+					  gettext_noop("Name"),
+					  gettext_noop("Definition"),
+					  gettext_noop("Description"));
+
+	if (!pattern)
+		appendPQExpBuffer(&buf, "      AND n.nspname <> 'pg_catalog'\n"
+				"      AND n.nspname <> 'information_schema'\n");
+
+#if TODO
+	processSQLNamePattern(pset.db, &buf, pattern, true, false,
+						  "n.nspname", "c.conname", NULL,
+						  "pg_catalog.pg_constraint_is_visible(c.oid)");
+#endif
+
+	appendPQExpBuffer(&buf, "ORDER BY 1, 2, 3, 4;");
+
+	res = PSQLexec(buf.data);
+	termPQExpBuffer(&buf);
+	if (!res)
+		return false;
+
+	myopt.nullPrint = NULL;
+	myopt.title = _("List of assertions");
+	myopt.translate_header = true;
+
+	printQuery(res, &myopt, pset.queryFout, false, pset.logfile);
+
+	PQclear(res);
+	return true;
+}
+
+
 /*
  * \dA
  * Takes an optional regexp to select particular access methods
@@ -2518,6 +2578,38 @@ describeOneTableDetails(const char *schemaname,
 			PQclear(result);
 		}
 
+		/* print assertions referencing this table (none if no triggers) */
+		if (tableinfo.hastriggers)
+		{
+			printfPQExpBuffer(&buf,
+							  "SELECT conname,\n"
+									  "  pg_catalog.pg_get_constraintdef(c.oid, true) AS condef\n"
+									  "FROM pg_catalog.pg_constraint c\n"
+									  "WHERE c.oid IN (SELECT objid FROM pg_depend WHERE classid = 'pg_constraint'::pg_catalog.regclass AND refclassid = 'pg_class'::pg_catalog.regclass AND refobjid = '%s')\n"
+									  "  AND c.conrelid = 0 AND c.contypid = 0 AND c.contype = 'c'\n"
+									  "ORDER BY 1",
+							  oid);
+			result = PSQLexec(buf.data);
+			if (!result)
+				goto error_return;
+			else
+				tuples = PQntuples(result);
+
+			if (tuples > 0)
+			{
+				printTableAddFooter(&cont, _("Assertions:"));
+				for (i = 0; i < tuples; i++)
+				{
+					printfPQExpBuffer(&buf, "    \"%s\" %s",
+									  PQgetvalue(result, i, 0),
+									  PQgetvalue(result, i, 1));
+
+					printTableAddFooter(&cont, buf.data);
+				}
+			}
+			PQclear(result);
+		}
+
 		/* print rules */
 		if (tableinfo.hasrules && tableinfo.relkind != RELKIND_MATVIEW)
 		{
diff --git a/src/bin/psql/describe.h b/src/bin/psql/describe.h
index a4cc5efae0..7b405b65da 100644
--- a/src/bin/psql/describe.h
+++ b/src/bin/psql/describe.h
@@ -15,6 +15,9 @@ extern bool describeAggregates(const char *pattern, bool verbose, bool showSyste
 /* \dA */
 extern bool describeAccessMethods(const char *pattern, bool verbose);
 
+/* \dQ */
+extern bool describeAssertions(const char *pattern);
+
 /* \db */
 extern bool describeTablespaces(const char *pattern, bool verbose);
 
diff --git a/src/bin/psql/help.c b/src/bin/psql/help.c
index 702e742af4..9deabd195f 100644
--- a/src/bin/psql/help.c
+++ b/src/bin/psql/help.c
@@ -223,6 +223,7 @@ slashUsage(unsigned short int pager)
 	fprintf(output, _("  \\d[S+]                 list tables, views, and sequences\n"));
 	fprintf(output, _("  \\d[S+]  NAME           describe table, view, sequence, or index\n"));
 	fprintf(output, _("  \\da[S]  [PATTERN]      list aggregates\n"));
+	fprintf(output, _("  \\dQ     [PATTERN]      list assertions\n"));
 	fprintf(output, _("  \\dA[+]  [PATTERN]      list access methods\n"));
 	fprintf(output, _("  \\db[+]  [PATTERN]      list tablespaces\n"));
 	fprintf(output, _("  \\dc[S+] [PATTERN]      list conversions\n"));
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 08d8ef09a4..923ee42a03 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -424,6 +424,24 @@ static const SchemaQuery Query_for_list_of_aggregates[] = {
 	}
 };
 
+static const SchemaQuery Query_for_list_of_assertions = {
+	/* min_server_version */
+	0,
+	/* catname */
+	"pg_catalog.pg_constraint c",
+	/* selcondition */
+	"(c.conrelid = 0 AND c.contypid = 0)",
+	/* viscondition */
+	"TRUE", //TODO: "pg_catalog.pg_constraint_is_visible(c.oid)",
+	/* namespace */
+	"c.connamespace",
+	/* result */
+	"pg_catalog.quote_ident(c.conname)",
+	/* qualresult */
+	NULL
+};
+
+
 static const SchemaQuery Query_for_list_of_datatypes = {
 	/* min_server_version */
 	0,
@@ -1192,6 +1210,7 @@ typedef struct
 static const pgsql_thing_t words_after_create[] = {
 	{"ACCESS METHOD", NULL, NULL, NULL, THING_NO_ALTER},
 	{"AGGREGATE", NULL, NULL, Query_for_list_of_aggregates},
+	{"ASSERTION", NULL, NULL, &Query_for_list_of_assertions},
 	{"CAST", NULL, NULL, NULL}, /* Casts have complex structures for names, so
 								 * skip it */
 	{"COLLATION", "SELECT pg_catalog.quote_ident(collname) FROM pg_catalog.pg_collation WHERE collencoding IN (-1, pg_catalog.pg_char_to_encoding(pg_catalog.getdatabaseencoding())) AND substring(pg_catalog.quote_ident(collname),1,%d)='%s'"},
@@ -1618,7 +1637,7 @@ psql_completion(const char *text, int start, int end)
 		"\\a",
 		"\\connect", "\\conninfo", "\\C", "\\cd", "\\copy",
 		"\\copyright", "\\crosstabview",
-		"\\d", "\\da", "\\dA", "\\db", "\\dc", "\\dC", "\\dd", "\\ddp", "\\dD",
+		"\\d", "\\da", "\\dA", "\\dQ", "\\db", "\\dc", "\\dC", "\\dd", "\\ddp", "\\dD",
 		"\\des", "\\det", "\\deu", "\\dew", "\\dE", "\\df",
 		"\\dF", "\\dFd", "\\dFp", "\\dFt", "\\dg", "\\di", "\\dl", "\\dL",
 		"\\dm", "\\dn", "\\do", "\\dO", "\\dp",
@@ -1769,6 +1788,11 @@ psql_completion(const char *text, int start, int end)
 	else if (Matches3("ALTER", "SCHEMA", MatchAny))
 		COMPLETE_WITH_LIST2("OWNER TO", "RENAME TO");
 
+	// TODO ASSERTION
+
+	else if (Matches3("ALTER", "ASSERTION", MatchAny))
+		COMPLETE_WITH_CONST("RENAME TO ");
+
 	/* ALTER COLLATION <name> */
 	else if (Matches3("ALTER", "COLLATION", MatchAny))
 		COMPLETE_WITH_LIST3("OWNER TO", "RENAME TO", "SET SCHEMA");
@@ -2896,7 +2920,7 @@ psql_completion(const char *text, int start, int end)
 /* DROP */
 	/* Complete DROP object with CASCADE / RESTRICT */
 	else if (Matches3("DROP",
-					  "COLLATION|CONVERSION|DOMAIN|EXTENSION|LANGUAGE|PUBLICATION|SCHEMA|SEQUENCE|SERVER|SUBSCRIPTION|STATISTICS|TABLE|TYPE|VIEW",
+					  "ASSERTION|COLLATION|CONVERSION|DOMAIN|EXTENSION|LANGUAGE|PUBLICATION|SCHEMA|SEQUENCE|SERVER|SUBSCRIPTION|STATISTICS|TABLE|TYPE|VIEW",
 					  MatchAny) ||
 			 Matches4("DROP", "ACCESS", "METHOD", MatchAny) ||
 			 (Matches4("DROP", "AGGREGATE|FUNCTION|PROCEDURE|ROUTINE", MatchAny, MatchAny) &&
@@ -3628,6 +3652,8 @@ psql_completion(const char *text, int start, int end)
 	}
 	else if (TailMatchesCS1("\\da*"))
 		COMPLETE_WITH_VERSIONED_SCHEMA_QUERY(Query_for_list_of_aggregates, NULL);
+	else if (TailMatchesCS1("\\dQ*"))
+		COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_assertions, NULL);
 	else if (TailMatchesCS1("\\dA*"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_access_methods);
 	else if (TailMatchesCS1("\\db*"))
diff --git a/src/include/catalog/namespace.h b/src/include/catalog/namespace.h
index 5f8cf4992e..841be6db59 100644
--- a/src/include/catalog/namespace.h
+++ b/src/include/catalog/namespace.h
@@ -140,6 +140,7 @@ extern bool OverrideSearchPathMatchesCurrent(OverrideSearchPath *path);
 extern void PushOverrideSearchPath(OverrideSearchPath *newpath);
 extern void PopOverrideSearchPath(void);
 
+extern Oid	get_assertion_oid(List *name, bool missing_ok);
 extern Oid	get_collation_oid(List *collname, bool missing_ok);
 extern Oid	get_conversion_oid(List *conname, bool missing_ok);
 extern Oid	FindDefaultConversionProc(int32 for_encoding, int32 to_encoding);
diff --git a/src/include/catalog/pg_constraint.h b/src/include/catalog/pg_constraint.h
index 8fca86d71e..060e436fcd 100644
--- a/src/include/catalog/pg_constraint.h
+++ b/src/include/catalog/pg_constraint.h
@@ -57,8 +57,7 @@ CATALOG(pg_constraint,2606)
 	 * contypid links to the pg_type row for a domain if this is a domain
 	 * constraint.  Otherwise it's 0.
 	 *
-	 * For SQL-style global ASSERTIONs, both conrelid and contypid would be
-	 * zero. This is not presently supported, however.
+	 * For SQL-style global ASSERTIONs, both conrelid and contypid are zero.
 	 */
 	Oid			contypid;		/* domain this constraint constrains */
 
diff --git a/src/include/catalog/pg_constraint_fn.h b/src/include/catalog/pg_constraint_fn.h
index d3351f4a83..9c44c4c6da 100644
--- a/src/include/catalog/pg_constraint_fn.h
+++ b/src/include/catalog/pg_constraint_fn.h
@@ -24,7 +24,7 @@ typedef enum ConstraintCategory
 {
 	CONSTRAINT_RELATION,
 	CONSTRAINT_DOMAIN,
-	CONSTRAINT_ASSERTION		/* for future expansion */
+	CONSTRAINT_ASSERTION
 } ConstraintCategory;
 
 extern Oid CreateConstraintEntry(const char *constraintName,
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 0fdb42f639..463190724d 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -2101,6 +2101,10 @@ DESCR("oid of replica identity index if any");
 DATA(insert OID = 1250 (  unique_key_recheck	PGNSP PGUID 12 1 0 0 0 f f f t f v s 0 0 2279 "" _null_ _null_ _null_ _null_ _null_ unique_key_recheck _null_ _null_ _null_ ));
 DESCR("deferred UNIQUE constraint check");
 
+DATA(insert OID = 3556 (  assertion_check	PGNSP PGUID 12 1 0 0 0 f f f t f v s 0 0 2279 "" _null_ _null_ _null_ _null_ _null_ assertion_check _null_ _null_ _null_ ));
+DESCR("assertion check");
+
+
 /* Generic referential integrity constraint triggers */
 DATA(insert OID = 1644 (  RI_FKey_check_ins		PGNSP PGUID 12 1 0 0 0 f f f t f v s 0 0 2279 "" _null_ _null_ _null_ _null_ _null_ RI_FKey_check_ins _null_ _null_ _null_ ));
 DESCR("referential integrity FOREIGN KEY ... REFERENCES");
diff --git a/src/include/commands/constraint.h b/src/include/commands/constraint.h
new file mode 100644
index 0000000000..98aa8f996e
--- /dev/null
+++ b/src/include/commands/constraint.h
@@ -0,0 +1,10 @@
+#ifndef CONSTRAINT_H
+#define CONSTRAINT_H
+
+#include "catalog/objectaddress.h"
+#include "nodes/parsenodes.h"
+
+extern ObjectAddress CreateAssertion(CreateAssertionStmt *stmt);
+extern ObjectAddress RenameAssertion(RenameStmt *stmt);
+
+#endif
\ No newline at end of file
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index 74b094a9c3..6c9b89e139 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -414,6 +414,7 @@ typedef enum NodeTag
 	T_DropSubscriptionStmt,
 	T_CreateStatsStmt,
 	T_AlterCollationStmt,
+	T_CreateAssertionStmt,
 	T_CallStmt,
 
 	/*
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 92082b3a7a..d63a7a28ec 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1635,6 +1635,7 @@ typedef enum ObjectType
 	OBJECT_AGGREGATE,
 	OBJECT_AMOP,
 	OBJECT_AMPROC,
+	OBJECT_ASSERTION,
 	OBJECT_ATTRIBUTE,			/* type's attribute, when distinct from column */
 	OBJECT_CAST,
 	OBJECT_COLUMN,
@@ -3283,6 +3284,16 @@ typedef struct ReindexStmt
 	int			options;		/* Reindex options flags */
 } ReindexStmt;
 
+/* ----------------------
+ *      CREATE ASSERTION Statement
+ */
+typedef struct CreateAssertionStmt
+{
+	NodeTag		type;
+	List    	*assertion_name;
+	Constraint	*constraint;
+} CreateAssertionStmt;
+
 /* ----------------------
  *		CREATE CONVERSION Statement
  * ----------------------
diff --git a/src/include/parser/parse_node.h b/src/include/parser/parse_node.h
index 0230543810..54a6b114ff 100644
--- a/src/include/parser/parse_node.h
+++ b/src/include/parser/parse_node.h
@@ -60,6 +60,7 @@ typedef enum ParseExprKind
 	EXPR_KIND_VALUES_SINGLE,	/* single-row VALUES (in INSERT only) */
 	EXPR_KIND_CHECK_CONSTRAINT, /* CHECK constraint for a table */
 	EXPR_KIND_DOMAIN_CHECK,		/* CHECK constraint for a domain */
+	EXPR_KIND_ASSERTION_CHECK,	/* CHECK constraint for an assertion */
 	EXPR_KIND_COLUMN_DEFAULT,	/* default value for a table column */
 	EXPR_KIND_FUNCTION_DEFAULT, /* default parameter value for function */
 	EXPR_KIND_INDEX_EXPRESSION, /* index expression */
diff --git a/src/include/utils/acl.h b/src/include/utils/acl.h
index f4d4be8d0d..2c10dd082f 100644
--- a/src/include/utils/acl.h
+++ b/src/include/utils/acl.h
@@ -295,6 +295,7 @@ extern bool pg_opclass_ownercheck(Oid opc_oid, Oid roleid);
 extern bool pg_opfamily_ownercheck(Oid opf_oid, Oid roleid);
 extern bool pg_database_ownercheck(Oid db_oid, Oid roleid);
 extern bool pg_collation_ownercheck(Oid coll_oid, Oid roleid);
+extern bool pg_constraint_ownercheck(Oid constr_oid, Oid roleid);
 extern bool pg_conversion_ownercheck(Oid conv_oid, Oid roleid);
 extern bool pg_ts_dict_ownercheck(Oid dict_oid, Oid roleid);
 extern bool pg_ts_config_ownercheck(Oid cfg_oid, Oid roleid);
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index e55ea4035b..f618270bc8 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -114,6 +114,7 @@ extern int	get_func_nargs(Oid funcid);
 extern Oid	get_func_signature(Oid funcid, Oid **argtypes, int *nargs);
 extern Oid	get_func_variadictype(Oid funcid);
 extern bool get_func_retset(Oid funcid);
+extern Oid  get_func_lang(Oid funcid);
 extern bool func_strict(Oid funcid);
 extern char func_volatile(Oid funcid);
 extern char func_parallel(Oid funcid);
diff --git a/src/test/regress/expected/assertions.out b/src/test/regress/expected/assertions.out
new file mode 100644
index 0000000000..7fc0d710a3
--- /dev/null
+++ b/src/test/regress/expected/assertions.out
@@ -0,0 +1,779 @@
+BEGIN TRANSACTION;
+--
+-- Create some helper views and functions to allow us to more easily
+-- assert which operations will cause an assertion to be checked.
+--
+CREATE OR REPLACE VIEW invalidating_operation
+  (assertion_name,
+   relation_name,
+   operation)
+AS
+SELECT c.conname,
+       cl.relname,
+       v.operation
+  FROM pg_trigger t
+  JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+  JOIN pg_proc p ON (t.tgfoid = p.oid)
+  JOIN pg_class cl ON (t.tgrelid = cl.oid)
+  JOIN (VALUES ('INSERT', 1<<2),
+               ('DELETE', 1<<3|1<<5),
+               ('UPDATE', 1<<4))
+    AS v(operation, mask) ON ((v.mask & tgtype) > 0)
+ WHERE t.tgisinternal
+   AND p.proname = 'assertion_check';
+CREATE OR REPLACE VIEW invalidating_by_update_of_column
+  (assertion_name,
+   relation_name,
+   column_name)
+AS
+SELECT c.conname,
+       cl.relname,
+       a.attname
+  FROM pg_trigger t INNER JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+                    INNER JOIN pg_proc p ON (t.tgfoid = p.oid)
+                    INNER JOIN pg_class cl ON (t.tgrelid = cl.oid)
+                    CROSS JOIN LATERAL UNNEST(t.tgattr) AS co(n)
+                    INNER JOIN pg_attribute a ON (a.attrelid = cl.oid AND attnum = co.n)
+ WHERE t.tgisinternal
+   AND p.proname = 'assertion_check'
+   AND (tgtype & (1 << 4)) > 0;
+CREATE OR REPLACE VIEW invalidating_summary
+  (assertion_name,
+   operations)
+AS
+SELECT assertion_name,
+       string_agg(operation, ' ' ORDER BY operation)
+  FROM (SELECT assertion_name,
+               operation ||'('|| string_agg(relation_name, ', ' ORDER BY relation_name) ||')'
+          FROM invalidating_operation
+         WHERE operation <> 'UPDATE'
+         GROUP BY assertion_name,
+                  operation
+         UNION
+        SELECT assertion_name,
+               operation ||'('|| string_agg(relation_name ||'.'|| column_name, ', ' ORDER BY relation_name, column_name) ||')'
+          FROM invalidating_by_update_of_column JOIN invalidating_operation USING (assertion_name, relation_name)
+         WHERE operation = 'UPDATE'
+         GROUP BY assertion_name,
+                  operation)
+    AS v(assertion_name, operation)
+ GROUP BY assertion_name;
+CREATE OR REPLACE FUNCTION have_identical_invalidating_operations
+  (a text, b text)
+RETURNS TABLE (predicate text, correct text)
+AS $$
+  SELECT 'assertion "'|| a ||'" has identical invalidating operations to assertion "'|| b ||'"',
+         CASE WHEN
+           NOT EXISTS (SELECT relation_name, operation
+                         FROM invalidating_operation
+                        WHERE assertion_name = a
+                       EXCEPT 
+                       SELECT relation_name, operation
+                         FROM invalidating_operation
+                        WHERE assertion_name = b) AND
+           NOT EXISTS (SELECT relation_name, column_name
+                         FROM invalidating_by_update_of_column
+                        WHERE assertion_name = a
+                       EXCEPT
+                       SELECT relation_name, column_name
+                         FROM invalidating_by_update_of_column
+                        WHERE assertion_name = b) THEN 'YES'
+                                                  ELSE 'NO' END
+$$ LANGUAGE SQL;
+COMMIT;
+BEGIN TRANSACTION;
+--
+-- Perform some basic sanity checking on creating assertions
+--
+CREATE TABLE test1 (a int, b text);
+CREATE ASSERTION foo CHECK (1 < 2);
+CREATE ASSERTION a2 CHECK ((SELECT count(*) FROM test1) < 5);
+DELETE FROM test1;
+INSERT INTO test1 VALUES (1, 'one');
+INSERT INTO test1 VALUES (2, 'two');
+INSERT INTO test1 VALUES (3, 'three');
+INSERT INTO test1 VALUES (4, 'four');
+SAVEPOINT pre_insert_too_many;
+INSERT INTO test1 VALUES (5, 'five');
+ERROR:  assertion "a2" violated
+ROLLBACK TO SAVEPOINT pre_insert_too_many;
+SELECT constraint_schema,
+       constraint_name
+  FROM information_schema.assertions
+ ORDER BY 1, 2;
+ constraint_schema | constraint_name 
+-------------------+-----------------
+ public            | a2
+ public            | foo
+(2 rows)
+
+\dQ
+                        List of assertions
+ Schema | Name |             Definition             | Description 
+--------+------+------------------------------------+-------------
+ public | a2   | CHECK ((( SELECT count(*) AS count+| 
+        |      |    FROM test1)) < 5)               | 
+ public | foo  | CHECK (1 < 2)                      | 
+(2 rows)
+
+ALTER ASSERTION a2 RENAME TO a3;
+SAVEPOINT pre_rename_foo;
+ALTER ASSERTION foo RENAME TO a3; -- fails
+ERROR:  assertion "a3" already exists
+ROLLBACK TO SAVEPOINT pre_rename_foo;
+DROP ASSERTION foo;
+SAVEPOINT pre_drop_test1;
+DROP TABLE test1; -- fails
+ERROR:  cannot drop table test1 because other objects depend on it
+DETAIL:  constraint a3 depends on table test1
+HINT:  Use DROP ... CASCADE to drop the dependent objects too.
+ROLLBACK TO SAVEPOINT pre_drop_test1;
+DROP TABLE test1 CASCADE;
+NOTICE:  drop cascades to constraint a3
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving various operators, functions and casts
+-- 
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+INSERT INTO t (n, p) VALUES (20, TRUE);
+CREATE ASSERTION is_distinct_from CHECK (10 IS DISTINCT FROM (SELECT MIN(n) FROM t));
+CREATE ASSERTION is_not_distinct_from CHECK (20 IS NOT DISTINCT FROM (SELECT MIN(n) FROM t));
+CREATE ASSERTION null_if CHECK (NULLIF((SELECT BOOL_AND(p) FROM t), FALSE));
+CREATE ASSERTION coerce_to_boolean_from_min CHECK (CAST((SELECT MIN(n) FROM t) AS BOOLEAN));
+CREATE ASSERTION coerce_to_boolean_from_bool_and CHECK (CAST((SELECT BOOL_AND(p) FROM t) AS BOOLEAN));
+CREATE ASSERTION coerce_to_boolean_from_boolean CHECK (CAST((SELECT TRUE FROM t) AS BOOLEAN));
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving function calls
+--
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL, d DATE NOT NULL);
+CREATE FUNCTION f(n INTEGER) RETURNS INTEGER
+AS $$
+  SELECT n * 2
+$$ LANGUAGE SQL;
+CREATE FUNCTION r(n INTEGER) RETURNS TABLE (m INTEGER )
+AS $$
+  SELECT m
+    FROM t
+   WHERE n > r.n
+$$ LANGUAGE SQL;
+CREATE ASSERTION age_of_d_in_t CHECK (
+  NOT EXISTS (
+    SELECT FROM t
+     WHERE AGE(DATE '01-01-2018') > INTERVAL '10 days' -- AGE(DATE) is built-in SQL
+  )
+);
+CREATE ASSERTION use_f CHECK (f(0) = 0);
+CREATE ASSERTION use_f_in_predicate CHECK (NOT EXISTS (SELECT FROM t WHERE f(n) = 20));
+CREATE ASSERTION use_f_in_target CHECK (NOT EXISTS (SELECT f(n) FROM t));
+CREATE ASSERTION use_r_in_from CHECK (NOT EXISTS (SELECT FROM r(100)));
+CREATE ASSERTION use_r_in_target CHECK (NOT EXISTS (SELECT r(100)));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (COALESCE(operations, 'NONE') = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('age_of_d_in_t',      'INSERT(t)'),
+       ('use_f',              'NONE'),
+       ('use_f_in_predicate', 'INSERT(t) UPDATE(t.n)'),
+       ('use_f_in_target',    'INSERT(t)'),
+       ('use_r_in_from',      'INSERT(t) UPDATE(t.m, t.n)'), -- TODO should _from and _target be the same?
+       ('use_r_in_target',    'INSERT(t) UPDATE(t.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+   assertion_name   |           actual           |          expected          | correct 
+--------------------+----------------------------+----------------------------+---------
+ age_of_d_in_t      | INSERT(t)                  | INSERT(t)                  | YES
+ use_f              | NONE                       | NONE                       | YES
+ use_f_in_predicate | INSERT(t) UPDATE(t.n)      | INSERT(t) UPDATE(t.n)      | YES
+ use_f_in_target    | INSERT(t)                  | INSERT(t)                  | YES
+ use_r_in_from      | INSERT(t) UPDATE(t.m, t.n) | INSERT(t) UPDATE(t.m, t.n) | YES
+ use_r_in_target    | INSERT(t) UPDATE(t.n)      | INSERT(t) UPDATE(t.n)      | YES
+(6 rows)
+
+CREATE FUNCTION g(n INTEGER) RETURNS INTEGER
+AS $$
+BEGIN
+  RETURN n * 2;
+END;
+$$ LANGUAGE PLPGSQL;
+-- Use of functions other than internal or those implemented in SQL are illegal
+CREATE ASSERTION use_g_in_from CHECK (NOT EXISTS (SELECT FROM g(100))); -- fails
+ERROR:  function "g" uses unsupported language "plpgsql"
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving EXISTS and NOT EXISTS
+--
+CREATE TABLE r (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+CREATE TABLE t1 (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+CREATE TABLE t2 (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+INSERT INTO r (n) VALUES (1);
+INSERT INTO t (n, m) VALUES (0, 0);
+INSERT INTO t1 (n, m) VALUES (0, 0);
+INSERT INTO t2 (n, m) VALUES (0, 0);
+CREATE ASSERTION exists_no_predicate CHECK (
+  EXISTS (SELECT FROM r)
+);
+CREATE ASSERTION exists_with_predicate CHECK (
+  EXISTS (SELECT FROM r WHERE n > 0)
+);
+CREATE ASSERTION not_exists_no_predicate CHECK (
+  NOT EXISTS (SELECT FROM s)
+);
+CREATE ASSERTION not_exists_with_predicate CHECK (
+  NOT EXISTS (SELECT FROM r WHERE n < 1)
+);
+CREATE ASSERTION direct_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t WHERE m = 0)
+);
+-- TODO These can be optimised, at least if the set operation is UNION.
+CREATE ASSERTION except_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t1 WHERE m = 0 EXCEPT SELECT n FROM t2 WHERE m = 1)
+);
+CREATE ASSERTION intersect_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t1 WHERE m = 0 INTERSECT SELECT n FROM t2 WHERE m = 0)
+);
+CREATE ASSERTION union_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t1 WHERE m = 0 UNION SELECT n FROM t2 WHERE m = 0)
+);
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('exists_no_predicate',            'DELETE(r)'),
+       ('exists_with_predicate',          'DELETE(r) UPDATE(r.n)'),
+       ('not_exists_no_predicate',        'INSERT(s)'),
+       ('not_exists_with_predicate',      'INSERT(r) UPDATE(r.n)'),
+       ('direct_subject_of_an_exists',    'DELETE(t) UPDATE(t.m)'),
+       ('except_subject_of_an_exists',    'DELETE(t1) INSERT(t2) UPDATE(t1.m, t1.n, t2.m, t2.n)'),
+       ('intersect_subject_of_an_exists', 'DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)'),
+       ('union_subject_of_an_exists',     'DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+         assertion_name         |                        actual                        |                       expected                       | correct 
+--------------------------------+------------------------------------------------------+------------------------------------------------------+---------
+ direct_subject_of_an_exists    | DELETE(t) UPDATE(t.m)                                | DELETE(t) UPDATE(t.m)                                | YES
+ except_subject_of_an_exists    | DELETE(t1) INSERT(t2) UPDATE(t1.m, t1.n, t2.m, t2.n) | DELETE(t1) INSERT(t2) UPDATE(t1.m, t1.n, t2.m, t2.n) | YES
+ exists_no_predicate            | DELETE(r)                                            | DELETE(r)                                            | YES
+ exists_with_predicate          | DELETE(r) UPDATE(r.n)                                | DELETE(r) UPDATE(r.n)                                | YES
+ intersect_subject_of_an_exists | DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)        | DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)        | YES
+ not_exists_no_predicate        | INSERT(s)                                            | INSERT(s)                                            | YES
+ not_exists_with_predicate      | INSERT(r) UPDATE(r.n)                                | INSERT(r) UPDATE(r.n)                                | YES
+ union_subject_of_an_exists     | DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)        | DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)        | YES
+(8 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving NOT
+--
+CREATE TABLE r (p BOOLEAN NOT NULL PRIMARY KEY);
+INSERT INTO r (p) VALUES (TRUE);
+CREATE ASSERTION a CHECK (EXISTS (SELECT FROM r WHERE p));
+CREATE ASSERTION b CHECK (NOT EXISTS (SELECT FROM r WHERE NOT p));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('a', 'DELETE(r) UPDATE(r.p)'),
+       ('b', 'INSERT(r) UPDATE(r.p)')) -- NOT(x) and x have opposite invalidating operations
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name |        actual         |       expected        | correct 
+----------------+-----------------------+-----------------------+---------
+ a              | DELETE(r) UPDATE(r.p) | DELETE(r) UPDATE(r.p) | YES
+ b              | INSERT(r) UPDATE(r.p) | INSERT(r) UPDATE(r.p) | YES
+(2 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving set operations INTERSECT, UNION, and EXCEPT
+--
+CREATE TABLE r (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY);
+INSERT INTO t (n) VALUES (0);
+CREATE ASSERTION except_operands CHECK (NOT EXISTS (SELECT FROM r EXCEPT SELECT FROM s));
+CREATE ASSERTION intersect_operands CHECK (NOT EXISTS (SELECT FROM r INTERSECT SELECT FROM s));
+CREATE ASSERTION union_operands CHECK (EXISTS (SELECT FROM s UNION SELECT FROM t));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('except_operands',    'DELETE(s) INSERT(r)'),
+       ('intersect_operands', 'INSERT(r, s)'),
+       ('union_operands',     'DELETE(s, t)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+   assertion_name   |       actual        |      expected       | correct 
+--------------------+---------------------+---------------------+---------
+ except_operands    | DELETE(s) INSERT(r) | DELETE(s) INSERT(r) | YES
+ intersect_operands | INSERT(r, s)        | INSERT(r, s)        | YES
+ union_operands     | DELETE(s, t)        | DELETE(s, t)        | YES
+(3 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving COUNT aggregations
+--
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+INSERT INTO s VALUES (1, 2);
+CREATE ASSERTION ge_all_count CHECK (1 >= ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION ge_any_count CHECK (1 >= ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION ge_count     CHECK (1 >=     (SELECT COUNT(*) FROM s));
+CREATE ASSERTION gt_all_count CHECK (2 >  ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION gt_any_count CHECK (2 >  ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION gt_count     CHECK (2 >      (SELECT COUNT(*) FROM s));
+CREATE ASSERTION le_all_count CHECK (1 <= ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION le_any_count CHECK (0 <= ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION le_count     CHECK (0 <=     (SELECT COUNT(*) FROM s));
+CREATE ASSERTION lt_all_count CHECK (0 <  ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION lt_any_count CHECK (0 <  ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION lt_count     CHECK (0 <      (SELECT COUNT(*) FROM s));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('ge_all_count', 'INSERT(s)'),
+       ('ge_any_count', 'INSERT(s)'),
+       ('ge_count',     'INSERT(s)'),
+       ('gt_all_count', 'INSERT(s)'),
+       ('gt_any_count', 'INSERT(s)'),
+       ('gt_count',     'INSERT(s)'),
+       ('le_all_count', 'DELETE(s)'),
+       ('le_any_count', 'DELETE(s)'),
+       ('le_count',     'DELETE(s)'),
+       ('lt_all_count', 'DELETE(s)'),
+       ('lt_any_count', 'DELETE(s)'),
+       ('lt_count',     'DELETE(s)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name |  actual   | expected  | correct 
+----------------+-----------+-----------+---------
+ ge_all_count   | INSERT(s) | INSERT(s) | YES
+ ge_any_count   | INSERT(s) | INSERT(s) | YES
+ ge_count       | INSERT(s) | INSERT(s) | YES
+ gt_all_count   | INSERT(s) | INSERT(s) | YES
+ gt_any_count   | INSERT(s) | INSERT(s) | YES
+ gt_count       | INSERT(s) | INSERT(s) | YES
+ le_all_count   | DELETE(s) | DELETE(s) | YES
+ le_any_count   | DELETE(s) | DELETE(s) | YES
+ le_count       | DELETE(s) | DELETE(s) | YES
+ lt_all_count   | DELETE(s) | DELETE(s) | YES
+ lt_any_count   | DELETE(s) | DELETE(s) | YES
+ lt_count       | DELETE(s) | DELETE(s) | YES
+(12 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving MIN aggregations
+--
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+INSERT INTO s VALUES (1, 2);
+CREATE ASSERTION ge_any_min CHECK (1 >= ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION ge_all_min CHECK (1 >= ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION ge_min     CHECK (1 >=     (SELECT MIN(n) FROM s));
+CREATE ASSERTION gt_any_min CHECK (2 >  ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION gt_all_min CHECK (2 >  ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION gt_min     CHECK (2 >      (SELECT MIN(n) FROM s));
+CREATE ASSERTION le_any_min CHECK (0 <= ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION le_all_min CHECK (0 <= ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION le_min     CHECK (0 <=     (SELECT MIN(n) FROM s));
+CREATE ASSERTION lt_any_min CHECK (0 <  ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION lt_all_min CHECK (0 <  ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION lt_min     CHECK (0 <      (SELECT MIN(n) FROM s));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('ge_all_min', 'DELETE(s) UPDATE(s.n)'),
+       ('ge_any_min', 'DELETE(s) UPDATE(s.n)'),
+       ('ge_min',     'DELETE(s) UPDATE(s.n)'),
+       ('gt_all_min', 'DELETE(s) UPDATE(s.n)'),
+       ('gt_any_min', 'DELETE(s) UPDATE(s.n)'),
+       ('gt_min',     'DELETE(s) UPDATE(s.n)'),
+       ('le_all_min', 'INSERT(s) UPDATE(s.n)'),
+       ('le_any_min', 'INSERT(s) UPDATE(s.n)'),
+       ('le_min',     'INSERT(s) UPDATE(s.n)'),
+       ('lt_all_min', 'INSERT(s) UPDATE(s.n)'),
+       ('lt_any_min', 'INSERT(s) UPDATE(s.n)'),
+       ('lt_min',     'INSERT(s) UPDATE(s.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name |        actual         |       expected        | correct 
+----------------+-----------------------+-----------------------+---------
+ ge_all_min     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ ge_any_min     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ ge_min         | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ gt_all_min     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ gt_any_min     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ gt_min         | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ le_all_min     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ le_any_min     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ le_min         | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ lt_all_min     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ lt_any_min     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ lt_min         | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+(12 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving MAX aggregations
+--
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+INSERT INTO s VALUES (1, 2);
+CREATE ASSERTION ge_any_max CHECK (1 >= ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION ge_all_max CHECK (1 >= ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION ge_max     CHECK (1 >=     (SELECT MAX(n) FROM s));
+CREATE ASSERTION gt_all_max CHECK (2 >  ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION gt_any_max CHECK (2 >  ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION gt_max     CHECK (2 >      (SELECT MAX(n) FROM s));
+CREATE ASSERTION le_all_max CHECK (0 <= ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION le_any_max CHECK (0 <= ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION le_max     CHECK (0 <=     (SELECT MAX(n) FROM s));
+CREATE ASSERTION lt_all_max CHECK (0 <  ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION lt_any_max CHECK (0 <  ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION lt_max     CHECK (0 <      (SELECT MAX(n) FROM s));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('ge_all_max', 'INSERT(s) UPDATE(s.n)'),
+       ('ge_any_max', 'INSERT(s) UPDATE(s.n)'),
+       ('ge_max',     'INSERT(s) UPDATE(s.n)'),
+       ('gt_all_max', 'INSERT(s) UPDATE(s.n)'),
+       ('gt_any_max', 'INSERT(s) UPDATE(s.n)'),
+       ('gt_max',     'INSERT(s) UPDATE(s.n)'),
+       ('le_all_max', 'DELETE(s) UPDATE(s.n)'),
+       ('le_any_max', 'DELETE(s) UPDATE(s.n)'),
+       ('le_max',     'DELETE(s) UPDATE(s.n)'),
+       ('lt_all_max', 'DELETE(s) UPDATE(s.n)'),
+       ('lt_any_max', 'DELETE(s) UPDATE(s.n)'),
+       ('lt_max',     'DELETE(s) UPDATE(s.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name |        actual         |       expected        | correct 
+----------------+-----------------------+-----------------------+---------
+ ge_all_max     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ ge_any_max     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ ge_max         | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ gt_all_max     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ gt_any_max     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ gt_max         | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ le_all_max     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ le_any_max     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ le_max         | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ lt_all_max     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ lt_any_max     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ lt_max         | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+(12 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving BOOL_AND aggregations
+--
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+INSERT INTO t (n, p) VALUES (0, TRUE);
+CREATE ASSERTION eq_bool_and     CHECK (TRUE  =      (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION eq_any_bool_and CHECK (TRUE  =  ANY (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION eq_all_bool_and CHECK (TRUE  =  ALL (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION ne_bool_and     CHECK (FALSE <>     (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION ne_any_bool_and CHECK (FALSE <> ANY (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION ne_all_bool_and CHECK (FALSE <> ALL (SELECT BOOL_AND(p) FROM t));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('eq_all_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('eq_any_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('eq_bool_and',     'INSERT(t) UPDATE(t.p)'),
+       ('ne_all_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('ne_any_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('ne_bool_and',     'INSERT(t) UPDATE(t.p)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name  |        actual         |       expected        | correct 
+-----------------+-----------------------+-----------------------+---------
+ eq_all_bool_and | INSERT(t) UPDATE(t.p) | INSERT(t) UPDATE(t.p) | YES
+ eq_any_bool_and | INSERT(t) UPDATE(t.p) | INSERT(t) UPDATE(t.p) | YES
+ eq_bool_and     | INSERT(t) UPDATE(t.p) | INSERT(t) UPDATE(t.p) | YES
+ ne_all_bool_and | INSERT(t) UPDATE(t.p) | INSERT(t) UPDATE(t.p) | YES
+ ne_any_bool_and | INSERT(t) UPDATE(t.p) | INSERT(t) UPDATE(t.p) | YES
+ ne_bool_and     | INSERT(t) UPDATE(t.p) | INSERT(t) UPDATE(t.p) | YES
+(6 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving BOOL_OR aggregations
+--
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+INSERT INTO t (n, p) VALUES (0, TRUE);
+CREATE ASSERTION eq_bool_or     CHECK (TRUE  =      (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION eq_any_bool_or CHECK (TRUE  =  ANY (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION eq_all_bool_or CHECK (TRUE  =  ALL (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION ne_bool_or     CHECK (FALSE <>     (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION ne_any_bool_or CHECK (FALSE <> ANY (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION ne_all_bool_or CHECK (FALSE <> ALL (SELECT BOOL_OR(p) FROM t));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('eq_all_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('eq_any_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('eq_bool_or',     'DELETE(t) UPDATE(t.p)'),
+       ('ne_all_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('ne_any_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('ne_bool_or',     'DELETE(t) UPDATE(t.p)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name |        actual         |       expected        | correct 
+----------------+-----------------------+-----------------------+---------
+ eq_all_bool_or | DELETE(t) UPDATE(t.p) | DELETE(t) UPDATE(t.p) | YES
+ eq_any_bool_or | DELETE(t) UPDATE(t.p) | DELETE(t) UPDATE(t.p) | YES
+ eq_bool_or     | DELETE(t) UPDATE(t.p) | DELETE(t) UPDATE(t.p) | YES
+ ne_all_bool_or | DELETE(t) UPDATE(t.p) | DELETE(t) UPDATE(t.p) | YES
+ ne_any_bool_or | DELETE(t) UPDATE(t.p) | DELETE(t) UPDATE(t.p) | YES
+ ne_bool_or     | DELETE(t) UPDATE(t.p) | DELETE(t) UPDATE(t.p) | YES
+(6 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving window functions
+--
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+-- Regular window function
+CREATE ASSERTION alternate_p CHECK (
+  NOT EXISTS (
+    SELECT FROM (
+      SELECT LAG(p, 1, NOT p) OVER n <> p
+         AND LEAD(p, 1, NOT p) OVER n <> p
+        FROM t
+      WINDOW n AS (ORDER BY n)
+    ) AS v(q)
+    WHERE NOT q
+  )
+);
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('alternate_p', 'DELETE(t) INSERT(t) UPDATE(t.n, t.p)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name |                actual                |               expected               | correct 
+----------------+--------------------------------------+--------------------------------------+---------
+ alternate_p    | DELETE(t) INSERT(t) UPDATE(t.n, t.p) | DELETE(t) INSERT(t) UPDATE(t.n, t.p) | YES
+(1 row)
+
+INSERT INTO t (n, p) VALUES (10, TRUE);
+INSERT INTO t (n, p) VALUES (20, FALSE);
+INSERT INTO t (n, p) VALUES (30, TRUE);
+SAVEPOINT pre_insert;
+INSERT INTO t (n, p) VALUES (40, TRUE);
+ERROR:  assertion "alternate_p" violated
+ROLLBACK TO SAVEPOINT pre_insert;
+SAVEPOINT pre_delete;
+DELETE FROM t WHERE n = 20;
+ERROR:  assertion "alternate_p" violated
+ROLLBACK TO SAVEPOINT pre_delete;
+SAVEPOINT pre_update;
+UPDATE t SET p = NOT p WHERE n = 20;
+ERROR:  assertion "alternate_p" violated
+ROLLBACK TO SAVEPOINT pre_update;
+DROP ASSERTION alternate_p;
+-- Aggregate function over a window
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+INSERT INTO s (n, m)
+SELECT n, (2 * n)
+  FROM GENERATE_SERIES(0, 9) AS ns(n);
+CREATE ASSERTION max_over_window CHECK ((10, 20) > ALL (SELECT n, MAX(m) OVER (ORDER BY n) FROM s));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('max_over_window', 'INSERT(s) UPDATE(s.m, s.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name  |           actual           |          expected          | correct 
+-----------------+----------------------------+----------------------------+---------
+ max_over_window | INSERT(s) UPDATE(s.m, s.n) | INSERT(s) UPDATE(s.m, s.n) | YES
+(1 row)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions containing a comparison should have the same invalidating
+-- operations as an expression containing the inverse comparison operation
+-- and where the operands have been switched
+--
+CREATE TABLE r (n INTEGER NOT NULL PRIMARY KEY);
+INSERT INTO r (n) VALUES (9);
+-- ">" and "<" are opposites
+CREATE ASSERTION a CHECK (10 > (SELECT MIN(n) FROM r));
+CREATE ASSERTION b CHECK ((SELECT MIN(n) FROM r) < 10);
+-- "<" and ">" are opposites
+CREATE ASSERTION c CHECK (8 < (SELECT MIN(n) FROM r));
+CREATE ASSERTION d CHECK ((SELECT MIN(n) FROM r) > 8);
+-- ">=" and "<=" are opposites
+CREATE ASSERTION e CHECK (9 >= (SELECT MIN(n) FROM r));
+CREATE ASSERTION f CHECK ((SELECT MIN(n) FROM r) <= 9);
+-- "<=" and ">=" are opposites
+CREATE ASSERTION g CHECK (9 <= (SELECT MIN(n) FROM r));
+CREATE ASSERTION h CHECK ((SELECT MIN(n) FROM r) >= 9);
+SELECT (test).predicate, (test).correct
+  FROM (
+VALUES ('a', 'b'),
+       ('c', 'd'),
+       ('e', 'f'),
+       ('g', 'h'))
+    AS v(a, b)
+ CROSS JOIN LATERAL (SELECT have_identical_invalidating_operations(v.a, v.b))
+    AS w(test)
+ ORDER BY 1, 2;
+                              predicate                               | correct 
+----------------------------------------------------------------------+---------
+ assertion "a" has identical invalidating operations to assertion "b" | YES
+ assertion "c" has identical invalidating operations to assertion "d" | YES
+ assertion "e" has identical invalidating operations to assertion "f" | YES
+ assertion "g" has identical invalidating operations to assertion "h" | YES
+(4 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- The INFORMATION_SCHEMA should contain the correct information
+--
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+CREATE ASSERTION a CHECK (NOT EXISTS (SELECT FROM t WHERE p));
+SELECT predicate,
+       CASE WHEN
+         truth THEN 'YES'
+               ELSE 'NO'
+       END AS correct
+  FROM ( 
+VALUES ('INFORMATION_SCHEMA.CONSTRAINT_TABLE_USAGE contains only the correct tables',
+        EXISTS (
+          SELECT FROM information_schema.constraint_table_usage
+           WHERE (constraint_name, table_name) = ('a', 't'))
+        AND NOT EXISTS (
+          SELECT FROM information_schema.constraint_table_usage
+           WHERE constraint_name = 'a'
+             AND table_name <> 't')),
+       ('INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE contains only the correct columns (t.p)',
+        EXISTS (
+          SELECT FROM information_schema.constraint_column_usage
+           WHERE (constraint_name, table_name, column_name) = ('a', 't', 'p'))
+        AND NOT EXISTS (
+          SELECT FROM information_schema.constraint_column_usage
+           WHERE constraint_name ='a'
+             AND (table_name, column_name) <> ('t', 'p'))),
+       ('INFORMATION_SCHEMA.ASSERTIONS contains only the correct assertions',
+        EXISTS (
+          SELECT FROM information_schema.assertions
+           WHERE constraint_name = 'a')
+        AND NOT EXISTS (
+          SELECT FROM information_schema.assertions
+           WHERE constraint_name <> 'a')))
+    AS v(predicate, truth);
+                                     predicate                                      | correct 
+------------------------------------------------------------------------------------+---------
+ INFORMATION_SCHEMA.CONSTRAINT_TABLE_USAGE contains only the correct tables         | YES
+ INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE contains only the correct columns (t.p) | YES
+ INFORMATION_SCHEMA.ASSERTIONS contains only the correct assertions                 | YES
+(3 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+-- TODO This needs rethinking
+/*
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+CREATE VIEW v AS SELECT * FROM s INNER JOIN t USING (n);
+
+CREATE ASSERTION a CHECK (NOT EXISTS (SELECT FROM v));
+
+-- we should depend on the view not the tables
+SELECT OK(depends_on('a', 'v'),
+          'Assertion depends upon the view v it references');
+SELECT OK(NOT depends_on('a', 's'),
+          'Assertion does not depend upon the table s referenced in the view v');
+SELECT OK(NOT depends_on('a', 't'),
+          'Assertion does not depend upon the table t referenced in the view v');
+
+-- we should trigger on the tables and not the view
+SELECT OK(EXISTS(SELECT FROM assertion_check_operation
+                  WHERE (assertion_name, relation_name) = ('a', 's')),
+          'Assertion is checked on modifications to table s');
+SELECT OK(EXISTS(SELECT FROM assertion_check_operation
+                  WHERE (assertion_name, relation_name) = ('a', 't')),
+          'Assertion is checked on modifications to table t');
+SELECT OK(NOT EXISTS(SELECT FROM assertion_check_operation
+                      WHERE (assertion_name, relation_name) = ('a', 'v')),
+          'Assertion is not checked on modifications to view v');
+*/
+ROLLBACK;
+-- TODO test commonalities between count, min, max, etc, for optimisations
+-- TODO ensure window function aggregates are treated the same as regular aggregates
+-- TODO ensure that conflicting aggregate functions are not incorrectly optimised
+-- TODO ensure that recorded dependencies are correct (traversal into functions and views)
+BEGIN TRANSACTION;
+DROP FUNCTION have_identical_invalidating_operations;
+DROP VIEW invalidating_summary;
+DROP VIEW invalidating_by_update_of_column;
+DROP VIEW invalidating_operation;
+COMMIT;
diff --git a/src/test/regress/parallel_schedule b/src/test/regress/parallel_schedule
index ad9434fb87..4966352197 100644
--- a/src/test/regress/parallel_schedule
+++ b/src/test/regress/parallel_schedule
@@ -60,7 +60,7 @@ test: create_index create_view
 # ----------
 # Another group of parallel tests
 # ----------
-test: create_aggregate create_function_3 create_cast constraints triggers inherit create_table_like typed_table vacuum drop_if_exists updatable_views rolenames roleattributes create_am hash_func
+test: create_aggregate create_function_3 create_cast constraints triggers inherit create_table_like typed_table vacuum drop_if_exists updatable_views rolenames roleattributes create_am assertions hash_func
 
 # ----------
 # sanity_check does a vacuum, affecting the sort order of SELECT *
diff --git a/src/test/regress/serial_schedule b/src/test/regress/serial_schedule
index 27cd49845e..e5277a278a 100644
--- a/src/test/regress/serial_schedule
+++ b/src/test/regress/serial_schedule
@@ -58,6 +58,7 @@ test: create_function_1
 test: create_type
 test: create_table
 test: create_function_2
+test: assertions
 test: copy
 test: copyselect
 test: copydml
diff --git a/src/test/regress/sql/assertions.sql b/src/test/regress/sql/assertions.sql
new file mode 100644
index 0000000000..f270698da1
--- /dev/null
+++ b/src/test/regress/sql/assertions.sql
@@ -0,0 +1,775 @@
+
+BEGIN TRANSACTION;
+
+--
+-- Create some helper views and functions to allow us to more easily
+-- assert which operations will cause an assertion to be checked.
+--
+
+CREATE OR REPLACE VIEW invalidating_operation
+  (assertion_name,
+   relation_name,
+   operation)
+AS
+SELECT c.conname,
+       cl.relname,
+       v.operation
+  FROM pg_trigger t
+  JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+  JOIN pg_proc p ON (t.tgfoid = p.oid)
+  JOIN pg_class cl ON (t.tgrelid = cl.oid)
+  JOIN (VALUES ('INSERT', 1<<2),
+               ('DELETE', 1<<3|1<<5),
+               ('UPDATE', 1<<4))
+    AS v(operation, mask) ON ((v.mask & tgtype) > 0)
+ WHERE t.tgisinternal
+   AND p.proname = 'assertion_check';
+
+CREATE OR REPLACE VIEW invalidating_by_update_of_column
+  (assertion_name,
+   relation_name,
+   column_name)
+AS
+SELECT c.conname,
+       cl.relname,
+       a.attname
+  FROM pg_trigger t INNER JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+                    INNER JOIN pg_proc p ON (t.tgfoid = p.oid)
+                    INNER JOIN pg_class cl ON (t.tgrelid = cl.oid)
+                    CROSS JOIN LATERAL UNNEST(t.tgattr) AS co(n)
+                    INNER JOIN pg_attribute a ON (a.attrelid = cl.oid AND attnum = co.n)
+ WHERE t.tgisinternal
+   AND p.proname = 'assertion_check'
+   AND (tgtype & (1 << 4)) > 0;
+
+CREATE OR REPLACE VIEW invalidating_summary
+  (assertion_name,
+   operations)
+AS
+SELECT assertion_name,
+       string_agg(operation, ' ' ORDER BY operation)
+  FROM (SELECT assertion_name,
+               operation ||'('|| string_agg(relation_name, ', ' ORDER BY relation_name) ||')'
+          FROM invalidating_operation
+         WHERE operation <> 'UPDATE'
+         GROUP BY assertion_name,
+                  operation
+         UNION
+        SELECT assertion_name,
+               operation ||'('|| string_agg(relation_name ||'.'|| column_name, ', ' ORDER BY relation_name, column_name) ||')'
+          FROM invalidating_by_update_of_column JOIN invalidating_operation USING (assertion_name, relation_name)
+         WHERE operation = 'UPDATE'
+         GROUP BY assertion_name,
+                  operation)
+    AS v(assertion_name, operation)
+ GROUP BY assertion_name;
+
+CREATE OR REPLACE FUNCTION have_identical_invalidating_operations
+  (a text, b text)
+RETURNS TABLE (predicate text, correct text)
+AS $$
+  SELECT 'assertion "'|| a ||'" has identical invalidating operations to assertion "'|| b ||'"',
+         CASE WHEN
+           NOT EXISTS (SELECT relation_name, operation
+                         FROM invalidating_operation
+                        WHERE assertion_name = a
+                       EXCEPT 
+                       SELECT relation_name, operation
+                         FROM invalidating_operation
+                        WHERE assertion_name = b) AND
+           NOT EXISTS (SELECT relation_name, column_name
+                         FROM invalidating_by_update_of_column
+                        WHERE assertion_name = a
+                       EXCEPT
+                       SELECT relation_name, column_name
+                         FROM invalidating_by_update_of_column
+                        WHERE assertion_name = b) THEN 'YES'
+                                                  ELSE 'NO' END
+$$ LANGUAGE SQL;
+
+COMMIT;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Perform some basic sanity checking on creating assertions
+--
+
+CREATE TABLE test1 (a int, b text);
+
+CREATE ASSERTION foo CHECK (1 < 2);
+CREATE ASSERTION a2 CHECK ((SELECT count(*) FROM test1) < 5);
+
+DELETE FROM test1;
+INSERT INTO test1 VALUES (1, 'one');
+INSERT INTO test1 VALUES (2, 'two');
+INSERT INTO test1 VALUES (3, 'three');
+INSERT INTO test1 VALUES (4, 'four');
+
+SAVEPOINT pre_insert_too_many;
+INSERT INTO test1 VALUES (5, 'five');
+ROLLBACK TO SAVEPOINT pre_insert_too_many;
+
+SELECT constraint_schema,
+       constraint_name
+  FROM information_schema.assertions
+ ORDER BY 1, 2;
+
+\dQ
+
+ALTER ASSERTION a2 RENAME TO a3;
+
+SAVEPOINT pre_rename_foo;
+ALTER ASSERTION foo RENAME TO a3; -- fails
+ROLLBACK TO SAVEPOINT pre_rename_foo;
+
+DROP ASSERTION foo;
+
+SAVEPOINT pre_drop_test1;
+DROP TABLE test1; -- fails
+ROLLBACK TO SAVEPOINT pre_drop_test1;
+
+DROP TABLE test1 CASCADE;
+
+ROLLBACK;
+
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving various operators, functions and casts
+-- 
+
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+
+INSERT INTO t (n, p) VALUES (20, TRUE);
+
+CREATE ASSERTION is_distinct_from CHECK (10 IS DISTINCT FROM (SELECT MIN(n) FROM t));
+CREATE ASSERTION is_not_distinct_from CHECK (20 IS NOT DISTINCT FROM (SELECT MIN(n) FROM t));
+CREATE ASSERTION null_if CHECK (NULLIF((SELECT BOOL_AND(p) FROM t), FALSE));
+CREATE ASSERTION coerce_to_boolean_from_min CHECK (CAST((SELECT MIN(n) FROM t) AS BOOLEAN));
+CREATE ASSERTION coerce_to_boolean_from_bool_and CHECK (CAST((SELECT BOOL_AND(p) FROM t) AS BOOLEAN));
+CREATE ASSERTION coerce_to_boolean_from_boolean CHECK (CAST((SELECT TRUE FROM t) AS BOOLEAN));
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving function calls
+--
+
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL, d DATE NOT NULL);
+
+CREATE FUNCTION f(n INTEGER) RETURNS INTEGER
+AS $$
+  SELECT n * 2
+$$ LANGUAGE SQL;
+
+CREATE FUNCTION r(n INTEGER) RETURNS TABLE (m INTEGER )
+AS $$
+  SELECT m
+    FROM t
+   WHERE n > r.n
+$$ LANGUAGE SQL;
+
+CREATE ASSERTION age_of_d_in_t CHECK (
+  NOT EXISTS (
+    SELECT FROM t
+     WHERE AGE(DATE '01-01-2018') > INTERVAL '10 days' -- AGE(DATE) is built-in SQL
+  )
+);
+CREATE ASSERTION use_f CHECK (f(0) = 0);
+CREATE ASSERTION use_f_in_predicate CHECK (NOT EXISTS (SELECT FROM t WHERE f(n) = 20));
+CREATE ASSERTION use_f_in_target CHECK (NOT EXISTS (SELECT f(n) FROM t));
+CREATE ASSERTION use_r_in_from CHECK (NOT EXISTS (SELECT FROM r(100)));
+CREATE ASSERTION use_r_in_target CHECK (NOT EXISTS (SELECT r(100)));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (COALESCE(operations, 'NONE') = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('age_of_d_in_t',      'INSERT(t)'),
+       ('use_f',              'NONE'),
+       ('use_f_in_predicate', 'INSERT(t) UPDATE(t.n)'),
+       ('use_f_in_target',    'INSERT(t)'),
+       ('use_r_in_from',      'INSERT(t) UPDATE(t.m, t.n)'), -- TODO should _from and _target be the same?
+       ('use_r_in_target',    'INSERT(t) UPDATE(t.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+CREATE FUNCTION g(n INTEGER) RETURNS INTEGER
+AS $$
+BEGIN
+  RETURN n * 2;
+END;
+$$ LANGUAGE PLPGSQL;
+
+-- Use of functions other than internal or those implemented in SQL are illegal
+CREATE ASSERTION use_g_in_from CHECK (NOT EXISTS (SELECT FROM g(100))); -- fails
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving EXISTS and NOT EXISTS
+--
+
+CREATE TABLE r (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+CREATE TABLE t1 (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+CREATE TABLE t2 (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+
+INSERT INTO r (n) VALUES (1);
+INSERT INTO t (n, m) VALUES (0, 0);
+INSERT INTO t1 (n, m) VALUES (0, 0);
+INSERT INTO t2 (n, m) VALUES (0, 0);
+
+CREATE ASSERTION exists_no_predicate CHECK (
+  EXISTS (SELECT FROM r)
+);
+
+CREATE ASSERTION exists_with_predicate CHECK (
+  EXISTS (SELECT FROM r WHERE n > 0)
+);
+
+CREATE ASSERTION not_exists_no_predicate CHECK (
+  NOT EXISTS (SELECT FROM s)
+);
+
+CREATE ASSERTION not_exists_with_predicate CHECK (
+  NOT EXISTS (SELECT FROM r WHERE n < 1)
+);
+
+CREATE ASSERTION direct_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t WHERE m = 0)
+);
+
+-- TODO These can be optimised, at least if the set operation is UNION.
+CREATE ASSERTION except_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t1 WHERE m = 0 EXCEPT SELECT n FROM t2 WHERE m = 1)
+);
+
+CREATE ASSERTION intersect_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t1 WHERE m = 0 INTERSECT SELECT n FROM t2 WHERE m = 0)
+);
+
+CREATE ASSERTION union_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t1 WHERE m = 0 UNION SELECT n FROM t2 WHERE m = 0)
+);
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('exists_no_predicate',            'DELETE(r)'),
+       ('exists_with_predicate',          'DELETE(r) UPDATE(r.n)'),
+       ('not_exists_no_predicate',        'INSERT(s)'),
+       ('not_exists_with_predicate',      'INSERT(r) UPDATE(r.n)'),
+       ('direct_subject_of_an_exists',    'DELETE(t) UPDATE(t.m)'),
+       ('except_subject_of_an_exists',    'DELETE(t1) INSERT(t2) UPDATE(t1.m, t1.n, t2.m, t2.n)'),
+       ('intersect_subject_of_an_exists', 'DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)'),
+       ('union_subject_of_an_exists',     'DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving NOT
+--
+
+CREATE TABLE r (p BOOLEAN NOT NULL PRIMARY KEY);
+
+INSERT INTO r (p) VALUES (TRUE);
+
+CREATE ASSERTION a CHECK (EXISTS (SELECT FROM r WHERE p));
+CREATE ASSERTION b CHECK (NOT EXISTS (SELECT FROM r WHERE NOT p));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('a', 'DELETE(r) UPDATE(r.p)'),
+       ('b', 'INSERT(r) UPDATE(r.p)')) -- NOT(x) and x have opposite invalidating operations
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving set operations INTERSECT, UNION, and EXCEPT
+--
+
+CREATE TABLE r (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY);
+
+INSERT INTO t (n) VALUES (0);
+
+CREATE ASSERTION except_operands CHECK (NOT EXISTS (SELECT FROM r EXCEPT SELECT FROM s));
+CREATE ASSERTION intersect_operands CHECK (NOT EXISTS (SELECT FROM r INTERSECT SELECT FROM s));
+CREATE ASSERTION union_operands CHECK (EXISTS (SELECT FROM s UNION SELECT FROM t));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('except_operands',    'DELETE(s) INSERT(r)'),
+       ('intersect_operands', 'INSERT(r, s)'),
+       ('union_operands',     'DELETE(s, t)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving COUNT aggregations
+--
+
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+
+INSERT INTO s VALUES (1, 2);
+
+CREATE ASSERTION ge_all_count CHECK (1 >= ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION ge_any_count CHECK (1 >= ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION ge_count     CHECK (1 >=     (SELECT COUNT(*) FROM s));
+CREATE ASSERTION gt_all_count CHECK (2 >  ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION gt_any_count CHECK (2 >  ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION gt_count     CHECK (2 >      (SELECT COUNT(*) FROM s));
+CREATE ASSERTION le_all_count CHECK (1 <= ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION le_any_count CHECK (0 <= ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION le_count     CHECK (0 <=     (SELECT COUNT(*) FROM s));
+CREATE ASSERTION lt_all_count CHECK (0 <  ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION lt_any_count CHECK (0 <  ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION lt_count     CHECK (0 <      (SELECT COUNT(*) FROM s));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('ge_all_count', 'INSERT(s)'),
+       ('ge_any_count', 'INSERT(s)'),
+       ('ge_count',     'INSERT(s)'),
+       ('gt_all_count', 'INSERT(s)'),
+       ('gt_any_count', 'INSERT(s)'),
+       ('gt_count',     'INSERT(s)'),
+       ('le_all_count', 'DELETE(s)'),
+       ('le_any_count', 'DELETE(s)'),
+       ('le_count',     'DELETE(s)'),
+       ('lt_all_count', 'DELETE(s)'),
+       ('lt_any_count', 'DELETE(s)'),
+       ('lt_count',     'DELETE(s)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving MIN aggregations
+--
+
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+
+INSERT INTO s VALUES (1, 2);
+
+CREATE ASSERTION ge_any_min CHECK (1 >= ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION ge_all_min CHECK (1 >= ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION ge_min     CHECK (1 >=     (SELECT MIN(n) FROM s));
+CREATE ASSERTION gt_any_min CHECK (2 >  ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION gt_all_min CHECK (2 >  ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION gt_min     CHECK (2 >      (SELECT MIN(n) FROM s));
+CREATE ASSERTION le_any_min CHECK (0 <= ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION le_all_min CHECK (0 <= ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION le_min     CHECK (0 <=     (SELECT MIN(n) FROM s));
+CREATE ASSERTION lt_any_min CHECK (0 <  ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION lt_all_min CHECK (0 <  ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION lt_min     CHECK (0 <      (SELECT MIN(n) FROM s));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('ge_all_min', 'DELETE(s) UPDATE(s.n)'),
+       ('ge_any_min', 'DELETE(s) UPDATE(s.n)'),
+       ('ge_min',     'DELETE(s) UPDATE(s.n)'),
+       ('gt_all_min', 'DELETE(s) UPDATE(s.n)'),
+       ('gt_any_min', 'DELETE(s) UPDATE(s.n)'),
+       ('gt_min',     'DELETE(s) UPDATE(s.n)'),
+       ('le_all_min', 'INSERT(s) UPDATE(s.n)'),
+       ('le_any_min', 'INSERT(s) UPDATE(s.n)'),
+       ('le_min',     'INSERT(s) UPDATE(s.n)'),
+       ('lt_all_min', 'INSERT(s) UPDATE(s.n)'),
+       ('lt_any_min', 'INSERT(s) UPDATE(s.n)'),
+       ('lt_min',     'INSERT(s) UPDATE(s.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving MAX aggregations
+--
+
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+
+INSERT INTO s VALUES (1, 2);
+
+CREATE ASSERTION ge_any_max CHECK (1 >= ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION ge_all_max CHECK (1 >= ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION ge_max     CHECK (1 >=     (SELECT MAX(n) FROM s));
+CREATE ASSERTION gt_all_max CHECK (2 >  ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION gt_any_max CHECK (2 >  ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION gt_max     CHECK (2 >      (SELECT MAX(n) FROM s));
+CREATE ASSERTION le_all_max CHECK (0 <= ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION le_any_max CHECK (0 <= ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION le_max     CHECK (0 <=     (SELECT MAX(n) FROM s));
+CREATE ASSERTION lt_all_max CHECK (0 <  ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION lt_any_max CHECK (0 <  ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION lt_max     CHECK (0 <      (SELECT MAX(n) FROM s));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('ge_all_max', 'INSERT(s) UPDATE(s.n)'),
+       ('ge_any_max', 'INSERT(s) UPDATE(s.n)'),
+       ('ge_max',     'INSERT(s) UPDATE(s.n)'),
+       ('gt_all_max', 'INSERT(s) UPDATE(s.n)'),
+       ('gt_any_max', 'INSERT(s) UPDATE(s.n)'),
+       ('gt_max',     'INSERT(s) UPDATE(s.n)'),
+       ('le_all_max', 'DELETE(s) UPDATE(s.n)'),
+       ('le_any_max', 'DELETE(s) UPDATE(s.n)'),
+       ('le_max',     'DELETE(s) UPDATE(s.n)'),
+       ('lt_all_max', 'DELETE(s) UPDATE(s.n)'),
+       ('lt_any_max', 'DELETE(s) UPDATE(s.n)'),
+       ('lt_max',     'DELETE(s) UPDATE(s.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving BOOL_AND aggregations
+--
+
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+INSERT INTO t (n, p) VALUES (0, TRUE);
+
+CREATE ASSERTION eq_bool_and     CHECK (TRUE  =      (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION eq_any_bool_and CHECK (TRUE  =  ANY (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION eq_all_bool_and CHECK (TRUE  =  ALL (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION ne_bool_and     CHECK (FALSE <>     (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION ne_any_bool_and CHECK (FALSE <> ANY (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION ne_all_bool_and CHECK (FALSE <> ALL (SELECT BOOL_AND(p) FROM t));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('eq_all_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('eq_any_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('eq_bool_and',     'INSERT(t) UPDATE(t.p)'),
+       ('ne_all_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('ne_any_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('ne_bool_and',     'INSERT(t) UPDATE(t.p)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving BOOL_OR aggregations
+--
+
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+INSERT INTO t (n, p) VALUES (0, TRUE);
+
+CREATE ASSERTION eq_bool_or     CHECK (TRUE  =      (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION eq_any_bool_or CHECK (TRUE  =  ANY (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION eq_all_bool_or CHECK (TRUE  =  ALL (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION ne_bool_or     CHECK (FALSE <>     (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION ne_any_bool_or CHECK (FALSE <> ANY (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION ne_all_bool_or CHECK (FALSE <> ALL (SELECT BOOL_OR(p) FROM t));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('eq_all_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('eq_any_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('eq_bool_or',     'DELETE(t) UPDATE(t.p)'),
+       ('ne_all_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('ne_any_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('ne_bool_or',     'DELETE(t) UPDATE(t.p)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving window functions
+--
+
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+
+-- Regular window function
+CREATE ASSERTION alternate_p CHECK (
+  NOT EXISTS (
+    SELECT FROM (
+      SELECT LAG(p, 1, NOT p) OVER n <> p
+         AND LEAD(p, 1, NOT p) OVER n <> p
+        FROM t
+      WINDOW n AS (ORDER BY n)
+    ) AS v(q)
+    WHERE NOT q
+  )
+);
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('alternate_p', 'DELETE(t) INSERT(t) UPDATE(t.n, t.p)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+INSERT INTO t (n, p) VALUES (10, TRUE);
+INSERT INTO t (n, p) VALUES (20, FALSE);
+INSERT INTO t (n, p) VALUES (30, TRUE);
+
+SAVEPOINT pre_insert;
+INSERT INTO t (n, p) VALUES (40, TRUE);
+ROLLBACK TO SAVEPOINT pre_insert;
+
+SAVEPOINT pre_delete;
+DELETE FROM t WHERE n = 20;
+ROLLBACK TO SAVEPOINT pre_delete;
+
+SAVEPOINT pre_update;
+UPDATE t SET p = NOT p WHERE n = 20;
+ROLLBACK TO SAVEPOINT pre_update;
+
+DROP ASSERTION alternate_p;
+
+-- Aggregate function over a window
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+
+INSERT INTO s (n, m)
+SELECT n, (2 * n)
+  FROM GENERATE_SERIES(0, 9) AS ns(n);
+
+CREATE ASSERTION max_over_window CHECK ((10, 20) > ALL (SELECT n, MAX(m) OVER (ORDER BY n) FROM s));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('max_over_window', 'INSERT(s) UPDATE(s.m, s.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions containing a comparison should have the same invalidating
+-- operations as an expression containing the inverse comparison operation
+-- and where the operands have been switched
+--
+
+CREATE TABLE r (n INTEGER NOT NULL PRIMARY KEY);
+
+INSERT INTO r (n) VALUES (9);
+
+-- ">" and "<" are opposites
+CREATE ASSERTION a CHECK (10 > (SELECT MIN(n) FROM r));
+CREATE ASSERTION b CHECK ((SELECT MIN(n) FROM r) < 10);
+
+-- "<" and ">" are opposites
+CREATE ASSERTION c CHECK (8 < (SELECT MIN(n) FROM r));
+CREATE ASSERTION d CHECK ((SELECT MIN(n) FROM r) > 8);
+
+-- ">=" and "<=" are opposites
+CREATE ASSERTION e CHECK (9 >= (SELECT MIN(n) FROM r));
+CREATE ASSERTION f CHECK ((SELECT MIN(n) FROM r) <= 9);
+
+-- "<=" and ">=" are opposites
+CREATE ASSERTION g CHECK (9 <= (SELECT MIN(n) FROM r));
+CREATE ASSERTION h CHECK ((SELECT MIN(n) FROM r) >= 9);
+
+SELECT (test).predicate, (test).correct
+  FROM (
+VALUES ('a', 'b'),
+       ('c', 'd'),
+       ('e', 'f'),
+       ('g', 'h'))
+    AS v(a, b)
+ CROSS JOIN LATERAL (SELECT have_identical_invalidating_operations(v.a, v.b))
+    AS w(test)
+ ORDER BY 1, 2;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- The INFORMATION_SCHEMA should contain the correct information
+--
+
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+CREATE ASSERTION a CHECK (NOT EXISTS (SELECT FROM t WHERE p));
+
+SELECT predicate,
+       CASE WHEN
+         truth THEN 'YES'
+               ELSE 'NO'
+       END AS correct
+  FROM ( 
+VALUES ('INFORMATION_SCHEMA.CONSTRAINT_TABLE_USAGE contains only the correct tables',
+        EXISTS (
+          SELECT FROM information_schema.constraint_table_usage
+           WHERE (constraint_name, table_name) = ('a', 't'))
+        AND NOT EXISTS (
+          SELECT FROM information_schema.constraint_table_usage
+           WHERE constraint_name = 'a'
+             AND table_name <> 't')),
+       ('INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE contains only the correct columns (t.p)',
+        EXISTS (
+          SELECT FROM information_schema.constraint_column_usage
+           WHERE (constraint_name, table_name, column_name) = ('a', 't', 'p'))
+        AND NOT EXISTS (
+          SELECT FROM information_schema.constraint_column_usage
+           WHERE constraint_name ='a'
+             AND (table_name, column_name) <> ('t', 'p'))),
+       ('INFORMATION_SCHEMA.ASSERTIONS contains only the correct assertions',
+        EXISTS (
+          SELECT FROM information_schema.assertions
+           WHERE constraint_name = 'a')
+        AND NOT EXISTS (
+          SELECT FROM information_schema.assertions
+           WHERE constraint_name <> 'a')))
+    AS v(predicate, truth);
+
+ROLLBACK;
+
+BEGIN TRANSACTION;
+-- TODO This needs rethinking
+/*
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+CREATE VIEW v AS SELECT * FROM s INNER JOIN t USING (n);
+
+CREATE ASSERTION a CHECK (NOT EXISTS (SELECT FROM v));
+
+-- we should depend on the view not the tables
+SELECT OK(depends_on('a', 'v'),
+          'Assertion depends upon the view v it references');
+SELECT OK(NOT depends_on('a', 's'),
+          'Assertion does not depend upon the table s referenced in the view v');
+SELECT OK(NOT depends_on('a', 't'),
+          'Assertion does not depend upon the table t referenced in the view v');
+
+-- we should trigger on the tables and not the view
+SELECT OK(EXISTS(SELECT FROM assertion_check_operation
+                  WHERE (assertion_name, relation_name) = ('a', 's')),
+          'Assertion is checked on modifications to table s');
+SELECT OK(EXISTS(SELECT FROM assertion_check_operation
+                  WHERE (assertion_name, relation_name) = ('a', 't')),
+          'Assertion is checked on modifications to table t');
+SELECT OK(NOT EXISTS(SELECT FROM assertion_check_operation
+                      WHERE (assertion_name, relation_name) = ('a', 'v')),
+          'Assertion is not checked on modifications to view v');
+*/
+ROLLBACK;
+
+-- TODO test commonalities between count, min, max, etc, for optimisations
+-- TODO ensure window function aggregates are treated the same as regular aggregates
+-- TODO ensure that conflicting aggregate functions are not incorrectly optimised
+-- TODO ensure that recorded dependencies are correct (traversal into functions and views)
+
+BEGIN TRANSACTION;
+
+DROP FUNCTION have_identical_invalidating_operations;
+DROP VIEW invalidating_summary;
+DROP VIEW invalidating_by_update_of_column;
+DROP VIEW invalidating_operation;
+
+COMMIT;
-- 
2.15.0

From bf4acbf4defacc89adc6ae08eea98314164a6052 Mon Sep 17 00:00:00 2001
From: Joe Wildish <joe@elusive.cx>
Date: Sun, 29 Apr 2018 19:10:26 +0100
Subject: [PATCH] SQL ASSERTION prototype

---
 doc/src/sgml/ddl.sgml                      |   31 +
 doc/src/sgml/ref/allfiles.sgml             |    3 +
 doc/src/sgml/ref/alter_assertion.sgml      |  139 ++++
 doc/src/sgml/ref/create_assertion.sgml     |  133 ++++
 doc/src/sgml/ref/drop_assertion.sgml       |  115 +++
 doc/src/sgml/reference.sgml                |    3 +
 src/backend/catalog/aclchk.c               |   33 +
 src/backend/catalog/information_schema.sql |   60 +-
 src/backend/catalog/namespace.c            |  121 +++
 src/backend/catalog/objectaddress.c        |   11 +
 src/backend/catalog/pg_constraint.c        |   20 +-
 src/backend/commands/alter.c               |    6 +
 src/backend/commands/constraint.c          | 1101 +++++++++++++++++++++++++++-
 src/backend/commands/event_trigger.c       |    6 +
 src/backend/nodes/copyfuncs.c              |   14 +
 src/backend/nodes/equalfuncs.c             |   12 +
 src/backend/parser/gram.y                  |   80 +-
 src/backend/parser/parse_agg.c             |    2 +
 src/backend/parser/parse_expr.c            |    2 +
 src/backend/parser/parse_func.c            |    4 +
 src/backend/tcop/utility.c                 |   20 +
 src/backend/utils/cache/lsyscache.c        |   19 +
 src/bin/psql/command.c                     |    3 +
 src/bin/psql/describe.c                    |   92 +++
 src/bin/psql/describe.h                    |    3 +
 src/bin/psql/help.c                        |    1 +
 src/bin/psql/tab-complete.c                |   30 +-
 src/include/catalog/namespace.h            |    1 +
 src/include/catalog/pg_constraint.h        |    5 +-
 src/include/catalog/pg_proc.dat            |    4 +
 src/include/commands/constraint.h          |   10 +
 src/include/nodes/nodes.h                  |    1 +
 src/include/nodes/parsenodes.h             |   11 +
 src/include/parser/parse_node.h            |    1 +
 src/include/utils/acl.h                    |    1 +
 src/include/utils/lsyscache.h              |    1 +
 src/test/regress/expected/assertions.out   |  779 ++++++++++++++++++++
 src/test/regress/parallel_schedule         |    2 +-
 src/test/regress/serial_schedule           |    1 +
 src/test/regress/sql/assertions.sql        |  775 ++++++++++++++++++++
 40 files changed, 3587 insertions(+), 69 deletions(-)
 create mode 100644 doc/src/sgml/ref/alter_assertion.sgml
 create mode 100644 doc/src/sgml/ref/create_assertion.sgml
 create mode 100644 doc/src/sgml/ref/drop_assertion.sgml
 create mode 100644 src/include/commands/constraint.h
 create mode 100644 src/test/regress/expected/assertions.out
 create mode 100644 src/test/regress/sql/assertions.sql

diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml
index 34da0d8d57..9340931fb5 100644
--- a/doc/src/sgml/ddl.sgml
+++ b/doc/src/sgml/ddl.sgml
@@ -917,6 +917,37 @@ CREATE TABLE circles (
     of the type specified in the constraint declaration.
    </para>
   </sect2>
+
+  <sect2 id="ddl-constraints-assertions">
+   <title>Assertions</title>
+   
+   <indexterm zone="ddl-constraints-assertions">
+    <primary>assertion</primary>
+   </indexterm>
+
+   <para>
+    An assertion is a constraint that is not part of a table
+    definition.  An assertion can define constraints that evaluate the
+    data across multiple rows of a table beyond what unique and
+    exclusion constraints can do, and assertions can look at the data
+    in multiple tables.
+   </para>
+
+   <para>
+    An assertion is a separate schema object and is created with the
+    command <command>CREATE ASSERTION</command>.  The constraint
+    expression is written as a <literal>CHECK</literal> clause like in
+    check constraints.  For instance, to ensure that there is always
+    at least one entry in the product table:
+<programlisting>
+CREATE ASSERTION products_not_empty CHECK ((SELECT count(*) FROM products) &gt; 0);
+</programlisting>
+    Assertions will often involve aggregate functions computed over
+    entire tables.  Note, however, that this kind of assertion can be
+   quite inefficient and should only be used on tables that are small
+    and change rarely.
+   </para>
+  </sect2>
  </sect1>
 
  <sect1 id="ddl-system-columns">
diff --git a/doc/src/sgml/ref/allfiles.sgml b/doc/src/sgml/ref/allfiles.sgml
index c81c87ef41..c06efc48c3 100644
--- a/doc/src/sgml/ref/allfiles.sgml
+++ b/doc/src/sgml/ref/allfiles.sgml
@@ -7,6 +7,7 @@ Complete list of usable sgml source files in this directory.
 <!-- SQL commands -->
 <!ENTITY abort              SYSTEM "abort.sgml">
 <!ENTITY alterAggregate     SYSTEM "alter_aggregate.sgml">
+<!ENTITY alterAssertion     SYSTEM "alter_assertion.sgml">
 <!ENTITY alterCollation     SYSTEM "alter_collation.sgml">
 <!ENTITY alterConversion    SYSTEM "alter_conversion.sgml">
 <!ENTITY alterDatabase      SYSTEM "alter_database.sgml">
@@ -60,6 +61,7 @@ Complete list of usable sgml source files in this directory.
 <!ENTITY copyTable          SYSTEM "copy.sgml">
 <!ENTITY createAccessMethod SYSTEM "create_access_method.sgml">
 <!ENTITY createAggregate    SYSTEM "create_aggregate.sgml">
+<!ENTITY createAssertion    SYSTEM "create_assertion.sgml">
 <!ENTITY createCast         SYSTEM "create_cast.sgml">
 <!ENTITY createCollation    SYSTEM "create_collation.sgml">
 <!ENTITY createConversion   SYSTEM "create_conversion.sgml">
@@ -107,6 +109,7 @@ Complete list of usable sgml source files in this directory.
 <!ENTITY do                 SYSTEM "do.sgml">
 <!ENTITY dropAccessMethod   SYSTEM "drop_access_method.sgml">
 <!ENTITY dropAggregate      SYSTEM "drop_aggregate.sgml">
+<!ENTITY dropAssertion      SYSTEM "drop_assertion.sgml">
 <!ENTITY dropCast           SYSTEM "drop_cast.sgml">
 <!ENTITY dropCollation      SYSTEM "drop_collation.sgml">
 <!ENTITY dropConversion     SYSTEM "drop_conversion.sgml">
diff --git a/doc/src/sgml/ref/alter_assertion.sgml b/doc/src/sgml/ref/alter_assertion.sgml
new file mode 100644
index 0000000000..b06417f740
--- /dev/null
+++ b/doc/src/sgml/ref/alter_assertion.sgml
@@ -0,0 +1,139 @@
+<!--
+doc/src/sgml/ref/alter_assertion.sgml
+PostgreSQL documentation
+-->
+
+<refentry id="sql-alterassertion">
+
+ <indexterm zone="sql-alterassertion">
+  <primary>ALTER ASSERTION</primary>
+ </indexterm>
+
+ <refmeta>
+  <refentrytitle>ALTER ASSERTION</refentrytitle>
+  <manvolnum>7</manvolnum>
+  <refmiscinfo>SQL - Language Statements</refmiscinfo>
+ </refmeta>
+
+ <refnamediv>
+  <refname>ALTER ASSERTION</refname>
+  <refpurpose>change the definition of an assertion</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+<synopsis>
+ALTER ASSERTION <replaceable>name</replaceable> RENAME TO <replaceable>new_name</replaceable>
+ALTER ASSERTION <replaceable>name</replaceable> OWNER TO <replaceable>new_owner</replaceable>
+ALTER ASSERTION <replaceable>name</replaceable> SET SCHEMA <replaceable>new_schema</replaceable>
+</synopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+  <title>Description</title>
+
+  <para>
+   <command>ALTER ASSERTION</command> changes the definition of an
+   assertion.
+  </para>
+
+  <para>
+   You must own the assertion to use <command>ALTER ASSERTION</command>.  To
+   change the schema of an assertion, you must also have
+   <literal>CREATE</literal> privilege on the new schema.  To alter
+   the owner, you must also be a direct or indirect member of the new
+   owning role, and that role must have <literal>CREATE</literal>
+   privilege on the assertion's schema.  (These restrictions enforce
+   that altering the owner doesn't do anything you couldn't do by
+   dropping and recreating the assertion.  However, a superuser can
+   alter ownership of any assertion anyway.)
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Parameters</title>
+
+  <variablelist>
+   <varlistentry>
+    <term><replaceable class="parameter">name</replaceable></term>
+    <listitem>
+     <para>
+      The name (optionally schema-qualified) of an existing assertion.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><replaceable class="parameter">new_name</replaceable></term>
+    <listitem>
+     <para>
+      The new name of the assertion.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><replaceable class="parameter">new_owner</replaceable></term>
+    <listitem>
+     <para>
+      The new owner of the assertion.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><replaceable class="parameter">new_schema</replaceable></term>
+    <listitem>
+     <para>
+      The new schema for the assertion.
+     </para>
+    </listitem>
+   </varlistentry>
+  </variablelist>
+ </refsect1>
+
+ <refsect1>
+  <title>Examples</title>
+
+  <para>
+   To rename the assertuib <literal>check_size</literal>
+   to <literal>check_count</literal>:
+<programlisting>
+ALTER ASSERTION check_size RENAME TO check_count;
+</programlisting>
+  </para>
+
+  <para>
+   To change the owner of the assertion <literal>check_size</literal>
+   to <literal>joe</literal>:
+<programlisting>
+ALTER ASSERTION check_size OWNER TO joe;
+</programlisting>
+  </para>
+
+  <para>
+   To move the assertion <literal>check_size</literal> into
+   schema <literal>myschema</literal>:
+<programlisting>
+ALTER ASSERTION check_size SET SCHEMA myschema;
+</programlisting>
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Compatibility</title>
+
+  <para>
+   There is no <command>ALTER ASSERTION</command> statement in the SQL
+   standard.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>See Also</title>
+
+  <simplelist type="inline">
+   <member><xref linkend="sql-createassertion"/></member>
+   <member><xref linkend="sql-dropassertion"/></member>
+  </simplelist>
+ </refsect1>
+</refentry>
diff --git a/doc/src/sgml/ref/create_assertion.sgml b/doc/src/sgml/ref/create_assertion.sgml
new file mode 100644
index 0000000000..b36d1b4ecb
--- /dev/null
+++ b/doc/src/sgml/ref/create_assertion.sgml
@@ -0,0 +1,133 @@
+<!--
+doc/src/sgml/ref/create_assertion.sgml
+PostgreSQL documentation
+-->
+
+<refentry id="sql-createassertion">
+ <indexterm zone="sql-createassertion">
+  <primary>CREATE ASSERTION</primary>
+ </indexterm>
+
+ <refmeta>
+  <refentrytitle>CREATE ASSERTION</refentrytitle>
+  <manvolnum>7</manvolnum>
+  <refmiscinfo>SQL - Language Statements</refmiscinfo>
+ </refmeta>
+
+ <refnamediv>
+  <refname>CREATE ASSERTION</refname>
+  <refpurpose>define a new assertion</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+<synopsis>
+CREATE ASSERTION <replaceable class="parameter">name</replaceable> CHECK ( <replaceable class="parameter">name</replaceable> ) [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
+</synopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+  <title>Description</title>
+
+  <para>
+   <command>CREATE ASSERTION</command> creates an assertion.  An
+   assertion is a check constraint that is independent of a table row
+   and a table.  It can therefore be used to enforce more complex
+   constraints across multiple table rows and across multiple tables.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Parameters</title>
+
+  <variablelist>
+   <varlistentry>
+    <term><replaceable class="parameter">name</replaceable></term>
+    <listitem>
+     <para>
+      The name (optionally schema-qualified) of the assertion to
+      create.  Assertions use the same namespace as constraints on
+      tables.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>CHECK ( <replaceable class="parameter">expression</replaceable> )</literal></term>
+    <listitem>
+     <para>
+      The <literal>CHECK</literal> clause specifies an expression producing a
+      Boolean result which the database must satisfy at all times for a
+      data change operation to succeed.  Expressions evaluating
+      to TRUE or UNKNOWN succeed.  Should the result of a data change
+      operation produce a FALSE result an error exception is
+      raised and the change is not made.
+     </para>
+
+     <para>
+      The check expression typically involves subselects in order to
+      read data from tables.  See the examples below.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>DEFERRABLE</literal></term>
+    <term><literal>NOT DEFERRABLE</literal></term>
+    <term><literal>INITIALLY IMMEDIATE</literal></term>
+    <term><literal>INITIALLY DEFERRED</literal></term>
+    <listitem>
+     <para>
+      These clauses control the deferrability of the constraint.  See
+      <xref linkend="sql-createtable"/> for an explanation.
+     </para>
+    </listitem>
+   </varlistentry>
+  </variablelist>
+ </refsect1>
+
+ <refsect1>
+  <title>Notes</title>
+
+  <para>
+   More specialized constraint forms such as table check constraints,
+   foreign-key constraints, or exclusion constraints should be used
+   instead when applicable, because they will be more efficient.
+  </para>
+
+  <para>
+   Assertion checks are not specially optimized.  For example,
+   checking the row count of a large table in an assertion will be
+   just as slow as implementing the check manually.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Examples</title>
+
+  <para>
+   Check that the table <literal>table1</literal> has at most 30 rows:
+<programlisting>
+CREATE ASSERTION table1_max30 CHECK ((SELECT count(*) FROM table1) &lt;= 30);
+</programlisting>
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Compatibility</title>
+
+  <para>
+   <command>CREATE ASSERTION</command> conforms to the SQL standard.
+   The PostgreSQL implementation has certain restrictions on what
+   check expressions are allowed in assertions.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>See Also</title>
+
+  <simplelist type="inline">
+   <member><xref linkend="sql-alterassertion"/></member>
+   <member><xref linkend="sql-dropassertion"/></member>
+  </simplelist>
+ </refsect1>
+</refentry>
diff --git a/doc/src/sgml/ref/drop_assertion.sgml b/doc/src/sgml/ref/drop_assertion.sgml
new file mode 100644
index 0000000000..39a60a0d29
--- /dev/null
+++ b/doc/src/sgml/ref/drop_assertion.sgml
@@ -0,0 +1,115 @@
+<!--
+doc/src/sgml/ref/drop_assertion.sgml
+PostgreSQL documentation
+-->
+
+<refentry id="sql-dropassertion">
+
+ <indexterm zone="sql-dropassertion">
+  <primary>DROP ASSERTION</primary>
+ </indexterm>
+
+ <refmeta>
+  <refentrytitle>DROP ASSERTION</refentrytitle>
+  <manvolnum>7</manvolnum>
+  <refmiscinfo>SQL - Language Statements</refmiscinfo>
+ </refmeta>
+
+ <refnamediv>
+  <refname>DROP ASSERTION</refname>
+  <refpurpose>remove an assertion</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+<synopsis>
+DROP ASSERTION [ IF EXISTS ] <replaceable class="parameter">name</replaceable> [, ...] [ CASCADE | RESTRICT ]
+</synopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+  <title>Description</title>
+
+  <para>
+   <command>DROP ASSERTION</command> removes an existing assertion. To
+   execute this command the current user must be the owner of the
+   assertion.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Parameters</title>
+
+  <variablelist>
+
+   <varlistentry>
+    <term><literal>IF EXISTS</literal></term>
+    <listitem>
+     <para>
+      Do not throw an error if the assertion does not exist. A notice
+      is issued in this case.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><replaceable class="parameter">name</replaceable></term>
+    <listitem>
+     <para>
+      The name (optionally schema-qualified) of an existing assertion.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>CASCADE</literal></term>
+    <listitem>
+     <para>
+      Automatically drop objects that depend on the assertion.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><literal>RESTRICT</literal></term>
+    <listitem>
+     <para>
+      Refuse to drop the assertion if any objects depend on it.  This
+      is the default.
+     </para>
+    </listitem>
+   </varlistentry>
+  </variablelist>
+ </refsect1>
+
+ <refsect1>
+  <title>Examples</title>
+
+  <para>
+   To remove the assertion <literal>check_size</literal>:
+<programlisting>
+DROP ASSERTION check_size;
+</programlisting>
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Compatibility</title>
+
+  <para>
+   This command conforms to the SQL standard, except that the standard
+   only allows one assertion to be dropped per command, and apart from
+   the <literal>IF EXISTS</literal> option, which is
+   a <productname>PostgreSQL</productname> extension.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>See Also</title>
+
+  <simplelist type="inline">
+   <member><xref linkend="sql-alterassertion"/></member>
+   <member><xref linkend="sql-createassertion"/></member>
+  </simplelist>
+ </refsect1>
+
+</refentry>
diff --git a/doc/src/sgml/reference.sgml b/doc/src/sgml/reference.sgml
index 73ef212c08..cca66b6391 100644
--- a/doc/src/sgml/reference.sgml
+++ b/doc/src/sgml/reference.sgml
@@ -35,6 +35,7 @@
 
    &abort;
    &alterAggregate;
+   &alterAssertion;
    &alterCollation;
    &alterConversion;
    &alterDatabase;
@@ -88,6 +89,7 @@
    &copyTable;
    &createAccessMethod;
    &createAggregate;
+   &createAssertion;
    &createCast;
    &createCollation;
    &createConversion;
@@ -135,6 +137,7 @@
    &do;
    &dropAccessMethod;
    &dropAggregate;
+   &dropAssertion;
    &dropCast;
    &dropCollation;
    &dropConversion;
diff --git a/src/backend/catalog/aclchk.c b/src/backend/catalog/aclchk.c
index 578e4c6592..bec1ad9381 100644
--- a/src/backend/catalog/aclchk.c
+++ b/src/backend/catalog/aclchk.c
@@ -3363,6 +3363,9 @@ aclcheck_error(AclResult aclerr, ObjectType objtype,
 					case OBJECT_AGGREGATE:
 						msg = gettext_noop("permission denied for aggregate %s");
 						break;
+					case OBJECT_ASSERTION:
+						msg = gettext_noop("permission denied for assertion %s");
+						break;
 					case OBJECT_COLLATION:
 						msg = gettext_noop("permission denied for collation %s");
 						break;
@@ -3494,6 +3497,9 @@ aclcheck_error(AclResult aclerr, ObjectType objtype,
 					case OBJECT_AGGREGATE:
 						msg = gettext_noop("must be owner of aggregate %s");
 						break;
+					case OBJECT_ASSERTION:
+						msg = gettext_noop("must be owner of assertion %s");
+						break;
 					case OBJECT_COLLATION:
 						msg = gettext_noop("must be owner of collation %s");
 						break;
@@ -5214,6 +5220,33 @@ pg_collation_ownercheck(Oid coll_oid, Oid roleid)
 	return has_privs_of_role(roleid, ownerId);
 }
 
+/*
+ * Ownership check for a constraint (specified by OID).
+ */
+bool
+pg_constraint_ownercheck(Oid constr_oid, Oid roleid)
+{
+	HeapTuple   tuple;
+	//Oid           ownerId;
+
+	/* Superusers bypass all permission checking. */
+	if (superuser_arg(roleid))
+		return true;
+
+	tuple = SearchSysCache1(CONSTROID, ObjectIdGetDatum(constr_oid));
+	if (!HeapTupleIsValid(tuple))
+		ereport(ERROR,
+			    (errcode(ERRCODE_UNDEFINED_OBJECT),
+			     errmsg("constraint with OID %u does not exist", constr_oid)));
+
+	//FIXME: ownerId = ((Form_pg_constraint) GETSTRUCT(tuple))->conowner;
+
+	ReleaseSysCache(tuple);
+
+	//return has_privs_of_role(roleid, ownerId);
+	return true; // for now
+}
+
 /*
  * Ownership check for a conversion (specified by OID).
  */
diff --git a/src/backend/catalog/information_schema.sql b/src/backend/catalog/information_schema.sql
index f4e69f4a26..23cc0759a3 100644
--- a/src/backend/catalog/information_schema.sql
+++ b/src/backend/catalog/information_schema.sql
@@ -285,7 +285,20 @@ GRANT SELECT ON administrable_role_authorizations TO PUBLIC;
  * ASSERTIONS view
  */
 
--- feature not supported
+CREATE VIEW assertions AS
+    SELECT CAST(current_database() AS sql_identifier) AS constraint_catalog,
+           CAST(n.nspname AS sql_identifier) AS constraint_schema,
+           CAST(con.conname AS sql_identifier) AS constraint_name,
+           CAST(CASE WHEN condeferrable THEN 'YES' ELSE 'NO' END
+             AS yes_or_no) AS is_deferrable,
+           CAST(CASE WHEN condeferred THEN 'YES' ELSE 'NO' END
+             AS yes_or_no) AS initially_deferred
+    FROM pg_namespace n, pg_constraint con
+    WHERE n.oid = con.connamespace
+          AND con.conrelid = 0 AND con.contypid = 0;
+          -- TODO: AND pg_has_role(con.conowner, 'USAGE');
+
+GRANT SELECT ON assertions TO PUBLIC;
 
 
 /*
@@ -790,7 +803,7 @@ CREATE VIEW constraint_column_usage AS
            CAST(cstrname AS sql_identifier) AS constraint_name
 
     FROM (
-        /* check constraints */
+        /* assertions and check constraints */
         SELECT DISTINCT nr.nspname, r.relname, r.relowner, a.attname, nc.nspname, c.conname
           FROM pg_namespace nr, pg_class r, pg_attribute a, pg_depend d, pg_namespace nc, pg_constraint c
           WHERE nr.oid = r.relnamespace
@@ -802,7 +815,7 @@ CREATE VIEW constraint_column_usage AS
             AND d.objid = c.oid
             AND c.connamespace = nc.oid
             AND c.contype = 'c'
-            AND r.relkind IN ('r', 'p')
+            AND r.relkind IN ('r', 'p', 'v')
             AND NOT a.attisdropped
 
         UNION ALL
@@ -842,20 +855,41 @@ GRANT SELECT ON constraint_column_usage TO PUBLIC;
 
 CREATE VIEW constraint_table_usage AS
     SELECT CAST(current_database() AS sql_identifier) AS table_catalog,
-           CAST(nr.nspname AS sql_identifier) AS table_schema,
-           CAST(r.relname AS sql_identifier) AS table_name,
+           CAST(tblschema AS sql_identifier) AS table_schema,
+           CAST(tblname AS sql_identifier) AS table_name,
            CAST(current_database() AS sql_identifier) AS constraint_catalog,
-           CAST(nc.nspname AS sql_identifier) AS constraint_schema,
-           CAST(c.conname AS sql_identifier) AS constraint_name
+           CAST(cstrschema AS sql_identifier) AS constraint_schema,
+           CAST(cstrname AS sql_identifier) AS constraint_name
+
+    FROM (
+        /* assertions and check constraints */
+        SELECT DISTINCT nr.nspname, r.relname, r.relowner, nc.nspname, c.conname
+          FROM pg_namespace nr, pg_class r,
+               pg_depend d, pg_namespace nc, pg_constraint c
+         WHERE nr.oid = r.relnamespace
+           AND d.refobjid = r.oid
+           AND c.connamespace = nc.oid
+           AND d.objid = c.oid
+           AND d.refclassid = 'pg_catalog.pg_class'::regclass
+           AND d.classid = 'pg_catalog.pg_constraint'::regclass
+           AND c.contype = 'c'
+           AND r.relkind IN ('r', 'p', 'v')
 
-    FROM pg_constraint c, pg_namespace nc,
-         pg_class r, pg_namespace nr
+        UNION ALL
 
-    WHERE c.connamespace = nc.oid AND r.relnamespace = nr.oid
-          AND ( (c.contype = 'f' AND c.confrelid = r.oid)
+        /* unique/primary key constraints */
+        SELECT nr.nspname, r.relname, r.relowner, nc.nspname, c.conname
+          FROM pg_constraint c, pg_namespace nc,
+               pg_class r, pg_namespace nr
+         WHERE c.connamespace = nc.oid
+           AND r.relnamespace = nr.oid
+           AND ( (c.contype = 'f' AND c.confrelid = r.oid)
              OR (c.contype IN ('p', 'u') AND c.conrelid = r.oid) )
-          AND r.relkind IN ('r', 'p')
-          AND pg_has_role(r.relowner, 'USAGE');
+           AND r.relkind IN ('r', 'p')
+
+    ) AS x (tblschema, tblname, tblowner, cstrschema, cstrname)
+
+    WHERE pg_has_role(x.tblowner, 'USAGE');
 
 GRANT SELECT ON constraint_table_usage TO PUBLIC;
 
diff --git a/src/backend/catalog/namespace.c b/src/backend/catalog/namespace.c
index 0f67a122ed..17f9c82f3d 100644
--- a/src/backend/catalog/namespace.c
+++ b/src/backend/catalog/namespace.c
@@ -27,6 +27,7 @@
 #include "catalog/objectaccess.h"
 #include "catalog/pg_authid.h"
 #include "catalog/pg_collation.h"
+#include "catalog/pg_constraint.h"
 #include "catalog/pg_conversion.h"
 #include "catalog/pg_namespace.h"
 #include "catalog/pg_opclass.h"
@@ -56,9 +57,11 @@
 #include "utils/lsyscache.h"
 #include "utils/memutils.h"
 #include "utils/syscache.h"
+#include "utils/fmgroids.h"
 #include "utils/varlena.h"
 
 
+
 /*
  * The namespace search path is a possibly-empty list of namespace OIDs.
  * In addition to the explicit list, implicitly-searched namespaces
@@ -3502,6 +3505,124 @@ PopOverrideSearchPath(void)
 }
 
 
+static Oid
+get_assertion_oid_internal(Relation pg_constraint, char *assertion_name, Oid namespaceId, List *name)
+{
+	SysScanDesc scan;
+	ScanKeyData skey[4];
+	HeapTuple	tuple;
+	Oid			conOid = InvalidOid;
+
+	ScanKeyInit(&skey[0],
+				Anum_pg_constraint_conname,
+				BTEqualStrategyNumber, F_NAMEEQ,
+				PointerGetDatum(assertion_name));
+
+	ScanKeyInit(&skey[1],
+				Anum_pg_constraint_connamespace,
+				BTEqualStrategyNumber, F_OIDEQ,
+				ObjectIdGetDatum(namespaceId));
+
+	ScanKeyInit(&skey[2],
+				Anum_pg_constraint_conrelid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				InvalidOid);
+
+	ScanKeyInit(&skey[3],
+				Anum_pg_constraint_contypid,
+				BTEqualStrategyNumber, F_OIDEQ,
+				InvalidOid);
+
+	scan = systable_beginscan(pg_constraint, InvalidOid, false,
+							  NULL, 4, skey);
+
+	/*
+	 * Fetch the constraint tuple from pg_constraint.  There may be
+	 * more than one match, because constraints are not required to
+	 * have unique names; if so, error out.
+	 */
+	while (HeapTupleIsValid(tuple = systable_getnext(scan)))
+	{
+		Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(tuple);
+
+		if (OidIsValid(con->conrelid) || OidIsValid(con->contypid))
+			ereport(ERROR,
+					(errmsg("constraint \"%s\" is not an assertion",
+							NameListToString(name))));
+
+		if (strcmp(NameStr(con->conname), assertion_name) == 0)
+		{
+			if (OidIsValid(conOid))
+				ereport(ERROR,
+						(errcode(ERRCODE_DUPLICATE_OBJECT),
+								errmsg("there are multiple assertions named \"%s\"",
+									   NameListToString(name))));
+			conOid = HeapTupleGetOid(tuple);
+		}
+	}
+
+	systable_endscan(scan);
+
+	return conOid;
+}
+
+/*
+ * get_assertion_oid
+ *		Find an assertion with the specified name.
+ *		Returns constraint's OID.
+ */
+Oid
+get_assertion_oid(List *name, bool missing_ok)
+{
+	char	   *schemaname;
+	char	   *assertion_name;
+	Oid			namespaceId;
+	Relation	pg_constraint;
+	Oid			conOid = InvalidOid;
+
+	DeconstructQualifiedName(name, &schemaname, &assertion_name);
+
+	pg_constraint = heap_open(ConstraintRelationId, AccessShareLock);
+
+	if (schemaname)
+	{
+		namespaceId = LookupExplicitNamespace(schemaname, missing_ok);
+		conOid = get_assertion_oid_internal(pg_constraint, assertion_name, namespaceId, name);
+	}
+	else
+	{
+		ListCell   *l;
+
+		recomputeNamespacePath();
+
+		foreach(l, activeSearchPath)
+		{
+			namespaceId = lfirst_oid(l);
+
+			if (namespaceId == myTempNamespace)
+				continue;		/* do not look in temp namespace */
+
+			conOid = get_assertion_oid_internal(pg_constraint, assertion_name, namespaceId, name);
+
+			if (OidIsValid(conOid))
+				break;
+		}
+	}
+
+	heap_close(pg_constraint, AccessShareLock);
+
+	/* If no such constraint exists, complain */
+	if (!OidIsValid(conOid) && !missing_ok)
+		ereport(ERROR,
+				(errcode(ERRCODE_UNDEFINED_OBJECT),
+						errmsg("assertion \"%s\" does not exist",
+							   NameListToString(name))));
+
+	return conOid;
+}
+
+
+
 /*
  * get_collation_oid - find a collation by possibly qualified name
  *
diff --git a/src/backend/catalog/objectaddress.c b/src/backend/catalog/objectaddress.c
index ef3ea64bd0..a513266a9e 100644
--- a/src/backend/catalog/objectaddress.c
+++ b/src/backend/catalog/objectaddress.c
@@ -898,6 +898,11 @@ get_object_address(ObjectType objtype, Node *object,
 				address.objectId = LookupOperWithArgs(castNode(ObjectWithArgs, object), missing_ok);
 				address.objectSubId = 0;
 				break;
+			case OBJECT_ASSERTION:
+				address.classId = ConstraintRelationId;
+				address.objectId = get_assertion_oid(castNode(List, object), missing_ok);
+				address.objectSubId = 0;
+				break;
 			case OBJECT_COLLATION:
 				address.classId = CollationRelationId;
 				address.objectId = get_collation_oid(castNode(List, object), missing_ok);
@@ -2116,6 +2121,7 @@ pg_get_object_address(PG_FUNCTION_ARGS)
 		case OBJECT_FOREIGN_TABLE:
 		case OBJECT_COLUMN:
 		case OBJECT_ATTRIBUTE:
+		case OBJECT_ASSERTION:
 		case OBJECT_COLLATION:
 		case OBJECT_CONVERSION:
 		case OBJECT_STATISTIC_EXT:
@@ -2276,6 +2282,11 @@ check_object_ownership(Oid roleid, ObjectType objtype, ObjectAddress address,
 				aclcheck_error(ACLCHECK_NOT_OWNER, objtype,
 							   strVal((Value *) object));
 			break;
+		case OBJECT_ASSERTION:
+			if (!pg_constraint_ownercheck(address.objectId, roleid))
+				aclcheck_error(ACLCHECK_NOT_OWNER, objtype,
+							   NameListToString(castNode(List, object)));
+			break;
 		case OBJECT_COLLATION:
 			if (!pg_collation_ownercheck(address.objectId, roleid))
 				aclcheck_error(ACLCHECK_NOT_OWNER, objtype,
diff --git a/src/backend/catalog/pg_constraint.c b/src/backend/catalog/pg_constraint.c
index 7a6d158f89..975ca60192 100644
--- a/src/backend/catalog/pg_constraint.c
+++ b/src/backend/catalog/pg_constraint.c
@@ -692,6 +692,13 @@ ConstraintNameIsUsed(ConstraintCategory conCat, Oid objId,
 			found = true;
 			break;
 		}
+		else if (conCat == CONSTRAINT_ASSERTION
+				 && con->conrelid == InvalidOid
+				 && con->contypid == InvalidOid)
+		{
+			found = true;
+			break;
+		}
 	}
 
 	systable_endscan(conscan);
@@ -863,8 +870,7 @@ RemoveConstraintById(Oid conId)
 		 * but we have no such concept at the moment.
 		 */
 	}
-	else
-		elog(ERROR, "constraint %u is not of a known type", conId);
+	/* Else it's an assertion; nothing special for that. */
 
 	/* Fry the constraint itself */
 	CatalogTupleDelete(conDesc, &tup->t_self);
@@ -920,6 +926,16 @@ RenameConstraintById(Oid conId, const char *newname)
 				(errcode(ERRCODE_DUPLICATE_OBJECT),
 				 errmsg("constraint \"%s\" for domain %s already exists",
 						newname, format_type_be(con->contypid))));
+	if (!OidIsValid(con->conrelid) &&
+		!OidIsValid(con->contypid) &&
+		ConstraintNameIsUsed(CONSTRAINT_ASSERTION,
+							 InvalidOid,
+							 con->connamespace,
+							 newname))
+		ereport(ERROR,
+				(errcode(ERRCODE_DUPLICATE_OBJECT),
+						errmsg("assertion \"%s\" already exists",
+							   newname)));
 
 	/* OK, do the rename --- tuple is a copy, so OK to scribble on it */
 	namestrcpy(&(con->conname), newname);
diff --git a/src/backend/commands/alter.c b/src/backend/commands/alter.c
index eff325cc7d..a9aa44ee5c 100644
--- a/src/backend/commands/alter.c
+++ b/src/backend/commands/alter.c
@@ -41,6 +41,7 @@
 #include "commands/alter.h"
 #include "commands/collationcmds.h"
 #include "commands/conversioncmds.h"
+#include "commands/constraint.h"
 #include "commands/dbcommands.h"
 #include "commands/defrem.h"
 #include "commands/event_trigger.h"
@@ -326,6 +327,9 @@ ExecRenameStmt(RenameStmt *stmt)
 {
 	switch (stmt->renameType)
 	{
+		case OBJECT_ASSERTION:
+			return RenameAssertion(stmt);
+
 		case OBJECT_TABCONSTRAINT:
 		case OBJECT_DOMCONSTRAINT:
 			return RenameConstraint(stmt);
@@ -491,6 +495,7 @@ ExecAlterObjectSchemaStmt(AlterObjectSchemaStmt *stmt,
 
 			/* generic code path */
 		case OBJECT_AGGREGATE:
+		case OBJECT_ASSERTION:
 		case OBJECT_COLLATION:
 		case OBJECT_CONVERSION:
 		case OBJECT_FUNCTION:
@@ -838,6 +843,7 @@ ExecAlterOwnerStmt(AlterOwnerStmt *stmt)
 
 			/* Generic cases */
 		case OBJECT_AGGREGATE:
+		case OBJECT_ASSERTION:
 		case OBJECT_COLLATION:
 		case OBJECT_CONVERSION:
 		case OBJECT_FUNCTION:
diff --git a/src/backend/commands/constraint.c b/src/backend/commands/constraint.c
index 90f19ad3dd..663f63d966 100644
--- a/src/backend/commands/constraint.c
+++ b/src/backend/commands/constraint.c
@@ -11,6 +11,8 @@
  *
  *-------------------------------------------------------------------------
  */
+
+
 #include "postgres.h"
 
 #include "catalog/index.h"
@@ -20,6 +22,39 @@
 #include "utils/rel.h"
 #include "utils/tqual.h"
 
+#include "access/htup_details.h"
+#include "catalog/dependency.h"
+#include "catalog/namespace.h"
+#include "catalog/pg_aggregate.h"
+#include "catalog/pg_constraint.h"
+#include "catalog/pg_operator.h"
+#include "catalog/pg_proc.h"
+#include "catalog/pg_language.h"
+#include "catalog/pg_trigger.h"
+#include "catalog/pg_type.h"
+#include "commands/constraint.h"
+#include "executor/functions.h"
+#include "executor/spi.h"
+#include "miscadmin.h"
+#include "nodes/makefuncs.h"
+#include "nodes/nodeFuncs.h"
+#include "optimizer/planner.h"
+#include "parser/analyze.h"
+#include "parser/parse_coerce.h"
+#include "parser/parse_expr.h"
+#include "parser/parse_node.h"
+#include "parser/parse_relation.h"
+#include "parser/parser.h"
+#include "parser/parsetree.h"
+#include "rewrite/rewriteHandler.h"
+#include "tcop/tcopprot.h"
+#include "utils/acl.h"
+#include "utils/lsyscache.h"
+#include "utils/snapmgr.h"
+#include "utils/syscache.h"
+#include "utils/ruleutils.h"
+#include "utils/fmgroids.h"
+
 
 /*
  * unique_key_recheck - trigger function to do a deferred uniqueness check.
@@ -39,15 +74,15 @@ unique_key_recheck(PG_FUNCTION_ARGS)
 {
 	TriggerData *trigdata = castNode(TriggerData, fcinfo->context);
 	const char *funcname = "unique_key_recheck";
-	HeapTuple	new_row;
+	HeapTuple new_row;
 	ItemPointerData tmptid;
-	Relation	indexRel;
-	IndexInfo  *indexInfo;
-	EState	   *estate;
+	Relation indexRel;
+	IndexInfo *indexInfo;
+	EState *estate;
 	ExprContext *econtext;
 	TupleTableSlot *slot;
-	Datum		values[INDEX_MAX_KEYS];
-	bool		isnull[INDEX_MAX_KEYS];
+	Datum values[INDEX_MAX_KEYS];
+	bool isnull[INDEX_MAX_KEYS];
 
 	/*
 	 * Make sure this is being called as an AFTER ROW trigger.  Note:
@@ -57,15 +92,15 @@ unique_key_recheck(PG_FUNCTION_ARGS)
 	if (!CALLED_AS_TRIGGER(fcinfo))
 		ereport(ERROR,
 				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
-				 errmsg("function \"%s\" was not called by trigger manager",
-						funcname)));
+					errmsg("function \"%s\" was not called by trigger manager",
+						   funcname)));
 
 	if (!TRIGGER_FIRED_AFTER(trigdata->tg_event) ||
 		!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
 		ereport(ERROR,
 				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
-				 errmsg("function \"%s\" must be fired AFTER ROW",
-						funcname)));
+					errmsg("function \"%s\" must be fired AFTER ROW",
+						   funcname)));
 
 	/*
 	 * Get the new data that was inserted/updated.
@@ -78,9 +113,9 @@ unique_key_recheck(PG_FUNCTION_ARGS)
 	{
 		ereport(ERROR,
 				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
-				 errmsg("function \"%s\" must be fired for INSERT or UPDATE",
-						funcname)));
-		new_row = NULL;			/* keep compiler quiet */
+					errmsg("function \"%s\" must be fired for INSERT or UPDATE",
+						   funcname)));
+		new_row = NULL;            /* keep compiler quiet */
 	}
 
 	/*
@@ -194,3 +229,1043 @@ unique_key_recheck(PG_FUNCTION_ARGS)
 
 	return PointerGetDatum(NULL);
 }
+
+
+static void
+test_assertion_expr(char *name, char *expression)
+{
+	char *sql;
+	int returnCode;
+	bool isNull;
+	Datum value;
+
+	if (SPI_connect() != SPI_OK_CONNECT)
+		elog(ERROR, "SPI connect failed when executing ASSERTION statement");
+
+	sql = psprintf("SELECT %s", expression);
+	returnCode = SPI_exec(sql, 1);
+
+	if (returnCode > 0 && SPI_tuptable != NULL)
+	{
+		value = SPI_getbinval(SPI_tuptable->vals[0], SPI_tuptable->tupdesc, 1, &isNull);
+		if (isNull)
+			ereport(ERROR,
+					(errcode(ERRCODE_CHECK_VIOLATION),
+							errmsg("assertion \"%s\" truth is unknown", name)));
+		else if (!isNull && !DatumGetBool(value))
+			ereport(ERROR,
+					(errcode(ERRCODE_CHECK_VIOLATION),
+							errmsg("assertion \"%s\" violated", name)));
+	}
+	else
+		elog(ERROR, "unexpected SPI result when executing ASSERTION statement");
+
+	SPI_finish();
+}
+
+
+Datum
+assertion_check(PG_FUNCTION_ARGS)
+{
+	TriggerData *trigdata = (TriggerData *) fcinfo->context;
+	const char *funcname = "assertion_check";
+	Oid constraintOid;
+	HeapTuple tup;
+	Datum adatum;
+	bool isNull;
+
+	/*
+	 * Make sure this is being called as an AFTER STATEMENT trigger.	Note:
+	 * translatable error strings are shared with ri_triggers.c, so resist the
+	 * temptation to fold the function name into them.
+	 */
+	if (!CALLED_AS_TRIGGER(fcinfo))
+		ereport(ERROR,
+				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
+					errmsg("function \"%s\" was not called by trigger manager",
+						   funcname)));
+
+	if (!TRIGGER_FIRED_AFTER(trigdata->tg_event) ||
+		!TRIGGER_FIRED_FOR_STATEMENT(trigdata->tg_event))
+		ereport(ERROR,
+				(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
+					errmsg("function \"%s\" must be fired AFTER STATEMENT",
+						   funcname)));
+
+	constraintOid = trigdata->tg_trigger->tgconstraint;
+	tup = SearchSysCache1(CONSTROID, ObjectIdGetDatum(constraintOid));
+	if (!HeapTupleIsValid(tup))
+		elog(ERROR, "cache lookup failed for constraint %u", constraintOid);
+
+	// XXX bogus
+	adatum = SysCacheGetAttr(CONSTROID, tup,
+							 Anum_pg_constraint_consrc, &isNull);
+	if (isNull)
+		elog(ERROR, "constraint %u has null consrc", constraintOid);
+
+	test_assertion_expr(get_constraint_name(constraintOid), TextDatumGetCString(adatum));
+
+	ReleaseSysCache(tup);
+	return PointerGetDatum(NULL);
+}
+
+#define NO_FUNC				(0)
+#define OTHER_FUNC			(1 << 0)
+#define MIN_AGG_FUNC		(1 << 1)
+#define MAX_AGG_FUNC		(1 << 2)
+#define COUNT_AGG_FUNC		(1 << 3)
+#define EVERY_AGG_FUNC		(1 << 4)
+#define BOOL_AND_AGG_FUNC	(1 << 5)
+#define BOOL_OR_AGG_FUNC	(1 << 6)
+
+#define EQ_COMPARISONS 		(bms_make_singleton(ROWCOMPARE_EQ))
+#define NE_COMPARISONS 		(bms_make_singleton(ROWCOMPARE_NE))
+#define LTE_COMPARISONS 	(bms_add_member(bms_make_singleton(ROWCOMPARE_LE), ROWCOMPARE_LT))
+#define GTE_COMPARISONS 	(bms_add_member(bms_make_singleton(ROWCOMPARE_GE), ROWCOMPARE_GT))
+
+#define MatchesOnly(a,b)	(((a) & (b)) && !((a) & (~(b))))
+#define CanOptimise(s) 		(!bms_is_empty(s) && \
+							(bms_is_subset(s, EQ_COMPARISONS)  || \
+							 bms_is_subset(s, NE_COMPARISONS)  || \
+							 bms_is_subset(s, LTE_COMPARISONS) || \
+							 bms_is_subset(s, GTE_COMPARISONS) ))
+
+
+// TODO review TODOs in the tests
+// TODO assertions should allow unknown according to the SQL specification
+// TODO traversal into views needs rethinking - dependencies?
+// TODO pg_dump support
+
+/*
+ * DML operations that could affect the truth of an assertion. Only
+ * INSERT and DELETE are considered as part of the labeling algorithm.
+ * UPDATEs are inferred using different logic.
+ */
+typedef enum DmlOp
+{
+	INSERT,
+	DELETE,
+	INSERT_DELETE
+} DmlOp;
+
+
+/*
+ * A context used to capture operations that may invalidate an assertion.
+ */
+typedef struct AssertionInfo
+{
+	DmlOp	label;         /* current invaliding operation */
+	Expr   *expr;          /* current Expression node */
+	List   *rtable;        /* current range tables */
+	List   *operators;     /* current operators */
+	SetOperation setOp;         /* current set-operation */
+	bool	invert;		   /* ... */
+	bool	inView;        /* if the walker has entered a view */
+	bool	inTargetEntry; /* if the walker has entered a TargetEntry node */
+	bool	inComparison;  /* if the walker has entered a comparison operation */
+	bool	inExists;      /* if the walker has entered an EXISTS node */
+
+	List   *dependencies; /* ... */
+	List   *relations;    /* relation Oids for all tables involved in the assertion check */
+	List   *inserts;      /* relation Oids for which INSERT could invalidate the assertion */
+	List   *deletes;      /* relation Oids for which DELETE could invalidate the assertion */
+	List   *updates;      /* relation Oids for which UPDATE could invalidate the assertion */
+	List   *columns;      /* list of ObjectAddresses referencing involved columns */
+} AssertionInfo;
+
+
+static void initAssertionInfo(AssertionInfo *info);
+static void copyAssertionInfo(AssertionInfo *target, AssertionInfo *source);
+static DmlOp oppositeDmlOp(DmlOp operation);
+static RowCompareType oppositeCompareType(RowCompareType type);
+static DmlOp labelForComparisonWithAggFuncs(DmlOp label, RowCompareType compOp, int aggFuncs);
+static int16 triggerOnEvents(AssertionInfo *info, Oid relationId);
+static List *triggerOnColumns(AssertionInfo *info, Oid relationId);
+static bool listContainsObjectAddress(List *list, ObjectAddress *address);
+static Bitmapset * strategiesForOperators(List *operators);
+static int functionsForTargetList(List *targetList);
+static int funcMaskForFuncOid(Oid funcOid);
+static Query * queryForSQLFunction(FuncExpr *funcExpr);
+
+/* Expression visiting */
+static bool visitAllNodes(Node *node, AssertionInfo *info);
+static bool visitRangeTblRef(RangeTblRef *node, AssertionInfo *info);
+static bool visitQuery(Query *node, AssertionInfo *info);
+static bool visitSetOperationStmt(SetOperationStmt *node, AssertionInfo *info);
+static bool visitBoolExpr(BoolExpr *node, AssertionInfo *info);
+static bool visitSubLink(SubLink *node, AssertionInfo *info);
+static bool visitFuncExpr(FuncExpr *node, AssertionInfo *info);
+static bool visitExpr(Expr *node, AssertionInfo *info);
+static bool visitVar(Var *node, AssertionInfo *info);
+
+/* TargetList visiting */
+static bool visitAggrefNodes(Node *node, int *aggFuncs);
+static bool visitAggref(Aggref *node, int *aggFuncs);
+static bool visitWindowFunc(WindowFunc *node, int *aggFuncs);
+
+
+static void
+initAssertionInfo(AssertionInfo *info)
+{
+	info->label = DELETE;
+	info->expr = NULL;
+	info->rtable = NIL;
+	info->operators = NIL;
+	info->setOp = SETOP_NONE;
+	info->invert = false;
+	info->inView = false;
+	info->inTargetEntry = false;
+	info->inComparison = false;
+	info->inExists = false;
+
+	info->dependencies = NIL;
+	info->relations = NIL;
+	info->inserts = NIL;
+	info->deletes = NIL;
+	info->updates = NIL;
+	info->columns = NIL;
+}
+
+
+static void
+copyAssertionInfo(AssertionInfo *target, AssertionInfo *source)
+{
+	target->label = source->label;
+	target->expr = source->expr;
+	target->rtable = source->rtable;
+	target->operators = source->operators;
+	target->setOp = source->setOp;
+	target->invert = source->invert;
+	target->inView = source->inView;
+	target->inTargetEntry = source->inTargetEntry;
+	target->inComparison = source->inComparison;
+	target->inExists = source->inExists;
+}
+
+
+static DmlOp
+oppositeDmlOp(DmlOp operation)
+{
+	switch (operation)
+	{
+		case INSERT:
+			return DELETE;
+		case DELETE:
+			return INSERT;
+		case INSERT_DELETE:
+			return INSERT_DELETE;
+	}
+}
+
+
+static RowCompareType
+oppositeCompareType(RowCompareType type)
+{
+	switch (type)
+	{
+		case ROWCOMPARE_LE:
+			return ROWCOMPARE_GE;
+		case ROWCOMPARE_LT:
+			return ROWCOMPARE_GT;
+		case ROWCOMPARE_GT:
+			return ROWCOMPARE_LT;
+		case ROWCOMPARE_GE:
+			return ROWCOMPARE_LE;
+		default:
+			return type; /* we do not flip EQ and NE comparisons */
+	}
+}
+
+
+static DmlOp
+labelForComparisonWithAggFuncs(DmlOp label, RowCompareType compOp, int aggFuncs)
+{
+	int stronger, weaker;
+
+	switch (compOp)
+	{
+		case ROWCOMPARE_LT:
+		case ROWCOMPARE_LE:
+			stronger = MIN_AGG_FUNC;
+			weaker = MAX_AGG_FUNC | COUNT_AGG_FUNC;
+			break;
+
+		case ROWCOMPARE_EQ:
+			stronger = BOOL_AND_AGG_FUNC | EVERY_AGG_FUNC;
+			weaker = BOOL_OR_AGG_FUNC;
+			break;
+
+		case ROWCOMPARE_NE:
+			stronger = BOOL_AND_AGG_FUNC | EVERY_AGG_FUNC;
+			weaker = BOOL_OR_AGG_FUNC;
+			break;
+
+		case ROWCOMPARE_GE:
+		case ROWCOMPARE_GT:
+			stronger = MAX_AGG_FUNC | COUNT_AGG_FUNC;
+			weaker = MIN_AGG_FUNC;
+			break;
+
+		default:
+			stronger = weaker = NO_FUNC;
+	}
+
+	if (MatchesOnly(aggFuncs, weaker))
+		return label;
+	else if (MatchesOnly(aggFuncs, stronger))
+		return oppositeDmlOp(label);
+	else
+		return INSERT_DELETE;
+}
+
+
+static int16
+triggerOnEvents(AssertionInfo *info, Oid relationId)
+{
+	int16 result = 0;
+	if (list_member_oid(info->inserts, relationId))
+		result |= TRIGGER_TYPE_INSERT;
+	if (list_member_oid(info->deletes, relationId))
+		result |= TRIGGER_TYPE_DELETE | TRIGGER_TYPE_TRUNCATE;
+	if (list_member_oid(info->updates, relationId))
+		result |= TRIGGER_TYPE_UPDATE;
+	return result;
+}
+
+
+/*
+ * Returns a list of string nodes, suitable for use in the trigger
+ * definition, that contain the column names to be triggered against
+ * on UPDATE operations.
+ */
+static List *
+triggerOnColumns(AssertionInfo *info, Oid relationId)
+{
+	List     	  *columns = NIL;
+	ListCell 	  *cell;
+
+	foreach(cell, info->columns)
+	{
+		ObjectAddress *column = (ObjectAddress *) lfirst(cell);
+		AttrNumber attrNumber = (AttrNumber) column->objectSubId;
+
+		if (column->objectId == relationId)
+		{
+			Value *name = makeString(get_attname(relationId, attrNumber, false));
+			columns = lappend(columns, name);
+		}
+	}
+
+	return columns;
+}
+
+
+static bool
+listContainsObjectAddress(List *list, ObjectAddress *address)
+{
+	ListCell 	  *cell;
+	ObjectAddress *item;
+
+	foreach(cell, list)
+	{
+		item = (ObjectAddress *) lfirst(cell);
+		if (item->classId == address->classId &&
+			item->objectId == address->objectId &&
+			item->objectSubId == address->objectSubId)
+			return true;
+	}
+
+	return false;
+}
+
+
+static Bitmapset *
+strategiesForOperators(List *operators)
+{
+	ListCell  *operatorCell;
+	Bitmapset *strategies = NULL;
+
+	foreach(operatorCell, operators)
+	{
+		Oid operator = lfirst_oid(operatorCell);
+		List *interpretations = get_op_btree_interpretation(operator);
+		ListCell *interpretationCell;
+
+		foreach(interpretationCell, interpretations)
+			strategies = bms_add_member(strategies,
+										((OpBtreeInterpretation *) lfirst(interpretationCell))->strategy);
+	}
+
+	return strategies;
+}
+
+
+static int
+functionsForTargetList(List *targetList)
+{
+	int functionMask = NO_FUNC;
+	expression_tree_walker((Node *) targetList, visitAggrefNodes, &functionMask);
+	return functionMask;
+}
+
+
+static int
+funcMaskForFuncOid(Oid funcOid)
+{
+	char *name = get_func_name(funcOid);
+
+	if (name == NULL)
+		return OTHER_FUNC;
+	else if (strncmp(name, "min", strlen("min")) == 0)
+		return MIN_AGG_FUNC;
+	else if (strncmp(name, "max", strlen("max")) == 0)
+		return MAX_AGG_FUNC;
+	else if (strncmp(name, "count", strlen("count")) == 0)
+		return COUNT_AGG_FUNC;
+	else if (strncmp(name, "every", strlen("every")) == 0)
+		return EVERY_AGG_FUNC;
+	else if (strncmp(name, "bool_and", strlen("bool_and")) == 0)
+		return BOOL_AND_AGG_FUNC;
+	else if (strncmp(name, "bool_or", strlen("bool_or")) == 0)
+		return BOOL_OR_AGG_FUNC;
+	else
+		return OTHER_FUNC;
+}
+
+
+static Query *
+queryForSQLFunction(FuncExpr *funcExpr)
+{
+	Oid			funcId;
+	Relation 	procRel;
+	HeapTuple	tuple;
+	Datum		datum;
+	bool		isNull;
+	char	   *sql;
+	List	   *rawParseTree;
+	ParseState *pstate;
+	Query	   *query;
+	SQLFunctionParseInfoPtr pinfo;
+
+	funcId = funcExpr->funcid;
+	procRel = heap_open(ProcedureRelationId, ShareLock);
+
+	tuple = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcId));
+	if (!HeapTupleIsValid(tuple))
+		elog(ERROR, "cache lookup failed for function %u", funcId);
+
+	datum = SysCacheGetAttr(PROCOID,
+							tuple,
+							Anum_pg_proc_prosrc,
+							&isNull);
+	if (isNull)
+		elog(ERROR, "null prosrc for function %u", funcId);
+
+	sql = TextDatumGetCString(datum);
+	rawParseTree = pg_parse_query(sql);
+
+	pinfo = prepare_sql_fn_parse_info(tuple,
+									  (Node *) funcExpr,
+									  funcExpr->inputcollid);
+
+	pstate = make_parsestate(NULL);
+	pstate->p_sourcetext = sql;
+	sql_fn_parser_setup(pstate, pinfo);
+
+	query = transformTopLevelStmt(pstate, linitial(rawParseTree));
+	free_parsestate(pstate);
+
+	ReleaseSysCache(tuple);
+	heap_close(procRel, NoLock);
+
+	return query;
+}
+
+
+static bool
+visitRangeTblRef(RangeTblRef *node, AssertionInfo *info)
+{
+	RangeTblEntry  *entry;
+	Oid				relationId;
+	RTEKind			rtekind;
+	char 		    relkind;
+	bool			result;
+
+	entry = rt_fetch(node->rtindex, info->rtable);
+	rtekind = entry->rtekind;
+	result = false;
+
+	if (rtekind == RTE_RELATION)
+	{
+		relationId = getrelid(node->rtindex, info->rtable);
+		relkind = get_rel_relkind(relationId);
+
+		if (relkind == RELKIND_RELATION)
+		{
+			if (info->label == INSERT || info->label == INSERT_DELETE)
+				info->inserts = list_append_unique_oid(info->inserts, relationId);
+
+			if (info->label == DELETE || info->label == INSERT_DELETE)
+				info->deletes = list_append_unique_oid(info->deletes, relationId);
+
+			if (!info->inView)
+				info->dependencies = list_append_unique_oid(info->dependencies, relationId);
+
+			info->relations = list_append_unique_oid(info->relations, relationId);
+
+		}
+		else if (relkind == RELKIND_VIEW)
+		{
+			Relation view = heap_open(relationId, AccessShareLock);
+			Query *query = get_view_query(view);
+
+			if (!info->inView)
+				info->dependencies = list_append_unique_oid(info->dependencies, relationId);
+
+			info->inView = true;
+			result = visitQuery(query, info);
+
+			heap_close(view, NoLock);
+		}
+
+	}
+	else if (rtekind == RTE_TABLEFUNC)
+	{
+		result = visitAllNodes((Node *) entry->tablefunc, info);
+	}
+	else if (rtekind == RTE_FUNCTION)
+	{
+		result = visitAllNodes((Node *) entry->functions, info);
+	}
+	else if (rtekind == RTE_SUBQUERY)
+	{
+		result = visitQuery(entry->subquery, info);
+	}
+
+	return result;
+}
+
+
+static bool
+visitQuery(Query *node, AssertionInfo *info)
+{
+	info->rtable = node->rtable;
+
+	if (info->inComparison)
+	{
+		int functions = functionsForTargetList(node->targetList);
+		Bitmapset *strategies = strategiesForOperators(info->operators);
+
+		if (CanOptimise(strategies))
+		{
+			RowCompareType rowCompareType = (RowCompareType) bms_first_member(strategies);
+			info->label = labelForComparisonWithAggFuncs(
+				info->label,
+				info->invert ? oppositeCompareType(rowCompareType) : rowCompareType,
+				functions
+			);
+		}
+		else
+		{
+			/*
+			 * Either no btree interpretation was found for the operator(s), there were
+			 * multiple interpretations that were incompatible with each other, or the
+			 * found interpretations were not able to be optimised. We must therefore
+			 * assume that both INSERT and DELETE operations may be invalidating.
+			 */
+			info->label = INSERT_DELETE;
+		}
+	}
+	else if (node->hasWindowFuncs)
+	{
+		info->label = INSERT_DELETE;
+	}
+
+	return query_tree_walker(node,
+							 visitAllNodes,
+							 info,
+							 QTW_IGNORE_RANGE_TABLE);
+}
+
+
+static bool
+visitSetOperationStmt(SetOperationStmt *node, AssertionInfo *info)
+{
+	info->setOp = node->op;
+
+	if (visitAllNodes(node->larg, info))
+		return true;
+
+	if (info->setOp == SETOP_EXCEPT)
+		info->label = oppositeDmlOp(info->label);
+
+	return visitAllNodes(node->rarg, info);
+}
+
+
+static bool
+visitBoolExpr(BoolExpr *node, AssertionInfo *info)
+{
+	if (node->boolop == NOT_EXPR)
+		info->label = oppositeDmlOp(info->label);
+
+	return expression_tree_walker((Node *) node, visitAllNodes, (void *) info);
+}
+
+
+// TODO refactor this function
+static bool
+visitSubLink(SubLink *node, AssertionInfo *info)
+{
+	List *operators;
+	bool  invert;
+	bool  inComparison;
+	bool  inExists;
+
+	switch (node->subLinkType)
+	{
+		case ARRAY_SUBLINK: // TODO write tests for this
+		case EXPR_SUBLINK:
+		{
+			Expr *expr = info->expr;
+			bool hasExpr = (expr != NULL);
+
+			if (hasExpr && IsA(expr, OpExpr))
+			{
+				OpExpr *opExpr = (OpExpr *) expr;
+				inComparison = true;
+				inExists = false;
+
+				/*
+				 * Optimisation code is written under the assumption that the sub-select is the
+				 * right operand. If it is the left operand the comparison needs to be inverted.
+				 */
+				invert = (list_nth_node(SubLink, opExpr->args, 0) == node);
+				operators = list_make1_oid(opExpr->opno);
+			}
+			else if (hasExpr && IsA(expr, FuncExpr) &&
+					((FuncExpr *)expr)->funcresulttype == BOOLOID)
+			{
+				/*
+				 * We are inside a function invocation that returns Boolean but is not an OpExpr.
+				 * Let's exploit the fact that "expr == TRUE -> expr", and pretend there is an
+				 * equality operator.
+				 */
+				inComparison = true;
+				inExists = false;
+				operators = list_make1_oid(F_BOOLEQ);
+				invert = false;
+			}
+			else if (exprType((const Node *) node) == BOOLOID)
+			{
+				/*
+				 * We are _not_ inside either an OpExpr or FuncExpr, but we are a query that can be
+				 * coerced to Boolean. We use the same logic above e.g. "expr == TRUE -> expr"
+				 */
+				inComparison = true;
+				inExists = false;
+				operators = list_make1_oid(F_BOOLEQ);
+				invert = false;
+			}
+			else
+			{
+				inComparison = false;
+				inExists = false;
+				invert = false;
+				operators = NIL;
+			}
+		}
+		break;
+
+		case ALL_SUBLINK:
+		case ANY_SUBLINK:
+		case ROWCOMPARE_SUBLINK:
+		{
+			if (IsA(node->testexpr, OpExpr))
+			{
+				OpExpr *expr = (OpExpr *) node->testexpr;
+				inComparison = true;
+				inExists = false;
+				invert = false;
+				operators = list_make1_oid(expr->opno);
+			}
+			else if (IsA(node->testexpr, RowCompareExpr))
+			{
+				RowCompareExpr *expr = (RowCompareExpr *) node->testexpr;
+				inComparison = true;
+				inExists = false;
+				invert = false;
+				operators = list_copy(expr->opnos);
+			}
+			else
+			{
+				inComparison = false;
+				inExists = false;
+				invert = false;
+				operators = NIL;
+			}
+		}
+		break;
+
+		case EXISTS_SUBLINK:
+		{
+			/* existential quantification, no operators */
+			inComparison = false;
+			inExists = true;
+			invert = false;
+			operators = NIL;
+		}
+		break;
+			// case MULTIEXPR_SUBLINK: // TODO write tests for MULTIEXPR_SUBLINK? -- or, can it only occur in UPDATEs?
+		default:
+		{
+			elog(ERROR, "unhandled sublink type %u", node->subLinkType);
+			return true;
+		}
+
+	}
+
+	info->operators = operators;
+	info->invert = invert;
+	info->inComparison = inComparison;
+	info->inExists = inExists;
+	info->setOp = SETOP_NONE;
+
+	return expression_tree_walker((Node *) node, visitAllNodes, (void *) info);
+}
+
+
+static bool
+visitTargetEntry(TargetEntry *node, AssertionInfo *info)
+{
+	info->inTargetEntry = true;
+	return expression_tree_walker((Node *) node, visitAllNodes, (void *) info);
+}
+
+
+static bool
+visitFromExpr(FromExpr *node, AssertionInfo *info)
+{
+	info->inExists = false;
+	info->inComparison = false;
+	return expression_tree_walker((Node *) node, visitAllNodes, (void *) info);
+}
+
+
+static bool
+visitFuncExpr(FuncExpr *node, AssertionInfo *info)
+{
+	Oid lang = get_func_lang(node->funcid);
+
+	info->expr = (Expr *) node;
+
+	if (!(lang == INTERNALlanguageId || lang == SQLlanguageId))
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_AMBIGUOUS_FUNCTION),
+				 errmsg("function \"%s\" uses unsupported language \"%s\"",
+				   get_func_name(node->funcid), get_language_name(lang, false))));
+		return true;
+	}
+
+	if (expression_tree_walker((Node *) node, visitAllNodes, (void *) info))
+		return true;
+
+	if (lang == SQLlanguageId)
+	{
+		Query *query = queryForSQLFunction(node);
+		Node *next;
+		if (node->funcretset)
+			next = (Node *) query;
+		else
+			next = (Node *) ((TargetEntry *) linitial(query->targetList))->expr;
+
+		return visitAllNodes(next, info);
+	}
+
+	return false;
+}
+
+
+static bool
+visitExpr(Expr *node, AssertionInfo *info)
+{
+	info->expr = node;
+	return expression_tree_walker((Node *) node, visitAllNodes, (void *) info);
+}
+
+
+static bool
+visitVar(Var *node, AssertionInfo *info)
+{
+	RangeTblEntry *entry = rt_fetch(node->varno, info->rtable);
+
+	// TODO we should do this only for Tables and not Views?
+	// TODO optimisations for set-operations
+	if (entry->rtekind == RTE_RELATION && !(info->inExists && info->setOp == SETOP_NONE))
+	{
+		Oid relationId = getrelid(node->varno, info->rtable);
+		ObjectAddress *column = (ObjectAddress *) palloc(sizeof(ObjectAddress));
+
+		column->classId = RelationRelationId;
+		column->objectId = relationId;
+		column->objectSubId = node->varattno;
+
+		if (!listContainsObjectAddress(info->columns, column))
+			info->columns = lcons(column, info->columns);
+
+		info->relations = list_append_unique_oid(info->relations, relationId);
+		info->updates = list_append_unique_oid(info->updates, relationId);
+	}
+
+	return expression_tree_walker((Node *) node, visitAllNodes, (void *) info);
+}
+
+
+static bool
+visitAllNodes(Node *node, AssertionInfo *info)
+{
+	AssertionInfo stored;
+	bool result;
+
+	copyAssertionInfo(&stored, info);
+
+	if (node == NULL)
+		result = false;
+	else if (IsA(node, RangeTblRef))
+		result = visitRangeTblRef((RangeTblRef *) node, info);
+	else if (IsA(node, Query))
+		result = visitQuery((Query *) node, info);
+	else if (IsA(node, BoolExpr))
+		result = visitBoolExpr((BoolExpr *) node, info);
+	else if (IsA(node, SubLink))
+		result = visitSubLink((SubLink *) node, info);
+	else if (IsA(node, SetOperationStmt))
+		result = visitSetOperationStmt((SetOperationStmt *) node, info);
+	else if (IsA(node, FuncExpr))
+		result = visitFuncExpr((FuncExpr *) node, info);
+	else if (IsA(node, OpExpr) ||
+			 IsA(node, DistinctExpr) ||
+			 IsA(node, NullIfExpr))
+		result = visitExpr((Expr *) node, info);
+	else if (IsA(node, TargetEntry))
+		result = visitTargetEntry((TargetEntry *) node, info);
+	else if (IsA(node, Var))
+		result = visitVar((Var *) node, info);
+	else if (IsA(node, FromExpr))
+		result = visitFromExpr((FromExpr *) node, info);
+	else
+		result = expression_tree_walker(node, visitAllNodes, (void *) info);
+
+	copyAssertionInfo(info, &stored);
+
+	return result;
+}
+
+
+static bool
+visitAggrefNodes(Node *node, int *aggFuncs)
+{
+	if (node == NULL)
+		return false;
+	else if (IsA(node, Aggref))
+		return visitAggref((Aggref *) node, aggFuncs);
+	else if(IsA(node, WindowFunc))
+		return visitWindowFunc((WindowFunc *) node, aggFuncs);
+	else
+		return expression_tree_walker(node, visitAggrefNodes, (void *) aggFuncs);
+}
+
+
+static bool
+visitAggref(Aggref *node, int *aggFuncs)
+{
+	*aggFuncs |= funcMaskForFuncOid(node->aggfnoid);
+	return expression_tree_walker((Node *) node, visitAggrefNodes, (void *) aggFuncs);
+}
+
+
+static bool
+visitWindowFunc(WindowFunc *node, int *aggFuncs)
+{
+	*aggFuncs |= funcMaskForFuncOid(node->winfnoid);
+
+	return expression_tree_walker((Node *) node, visitAggrefNodes, (void *) aggFuncs);
+}
+
+
+ObjectAddress
+CreateAssertion(CreateAssertionStmt *stmt)
+{
+	Oid namespaceId;
+	char *assertion_name;
+	AclResult aclresult;
+	Node *expr;
+	ParseState *pstate;
+	char *ccsrc;
+	char *ccbin;
+	Oid constrOid;
+	AssertionInfo info;
+	ListCell *lc;
+	ObjectAddress address;
+
+	namespaceId = QualifiedNameGetCreationNamespace(stmt->assertion_name,
+													&assertion_name);
+
+	aclresult = pg_namespace_aclcheck(namespaceId, GetUserId(), ACL_CREATE);
+	if (aclresult != ACLCHECK_OK)
+		aclcheck_error(aclresult, OBJECT_SCHEMA,
+					   get_namespace_name(namespaceId));
+
+	if (ConstraintNameIsUsed(CONSTRAINT_ASSERTION, InvalidOid, namespaceId, assertion_name))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_NAME),
+				 errmsg("assertion \"%s\" already exists", assertion_name)));
+
+	pstate = make_parsestate(NULL);
+	expr = transformExpr(pstate, stmt->constraint->raw_expr, EXPR_KIND_ASSERTION_CHECK);
+	expr = coerce_to_boolean(pstate, expr, "CHECK");
+
+	ccbin = nodeToString(expr);
+	ccsrc = deparse_expression(expr, NIL, false, false);
+
+	constrOid = CreateConstraintEntry(assertion_name,
+									  namespaceId,
+									  CONSTRAINT_CHECK, /* constraint type */
+									  stmt->constraint->deferrable,
+									  stmt->constraint->initdeferred,
+									  !stmt->constraint->skip_validation,
+									  InvalidOid, /* no parent constraint */
+									  InvalidOid, /* not a relation constraint */
+									  NULL,       /* no keys */
+									  0,          /* no keys */
+									  0,          /* no keys */
+									  InvalidOid, /* not a domain constraint */
+									  InvalidOid, /* no associated index */
+									  InvalidOid, /* foreign key fields ... */
+									  NULL,
+									  NULL,
+									  NULL,
+									  NULL,
+									  0,
+									  ' ',
+									  ' ',
+									  ' ',
+									  NULL,    /* not an exclusion constraint */
+									  expr, /* tree form of check constraint */
+									  ccbin, /* binary form of check constraint */
+									  ccsrc, /* source form of check constraint */
+									  true, /* is local */
+									  0,   /* inhcount */
+									  false, /* noinherit XXX */
+									  false); /* is_internal */
+
+	initAssertionInfo(&info);
+	visitAllNodes(expr, &info);
+
+	foreach (lc, info.relations)
+	{
+		Oid relationId = lfirst_oid(lc);
+		CreateTrigStmt *trigger;
+		Relation rel;
+
+		rel = heap_open(relationId, ShareLock); // XXX
+
+		trigger = makeNode(CreateTrigStmt);
+		trigger->trigname = "AssertionTrigger";
+		trigger->relation = makeRangeVar(get_namespace_name(namespaceId),
+										 pstrdup(RelationGetRelationName(rel)),
+										 -1);
+		trigger->funcname = SystemFuncName("assertion_check");
+		trigger->args = NIL;
+		trigger->row = false;
+		trigger->timing = TRIGGER_TYPE_AFTER;
+		trigger->events = triggerOnEvents(&info, relationId);
+		trigger->columns = triggerOnColumns(&info, relationId);
+		trigger->whenClause = NULL;
+		trigger->isconstraint = true;
+		trigger->deferrable = stmt->constraint->deferrable;
+		trigger->initdeferred = stmt->constraint->initdeferred;
+		trigger->constrrel = NULL;
+
+		CreateTrigger(trigger,
+		              NULL,
+			      InvalidOid,
+			      relationId,
+			      constrOid,
+			      InvalidOid, /* no index */
+			      InvalidOid, /* no func - use trigger->funcname */
+			      InvalidOid, /* no parent */
+			      NULL,       /* no when */
+			      true,       /* is_internal */
+			      false);
+
+		heap_close(rel, NoLock);
+	}
+
+	/*
+	 * Record dependencies between the constraint and the relations found in the
+	 * top-level expression. Dependencies to specific columns will already have
+	 * been recorded by the trigger creation.
+	 */
+	ObjectAddress myself, referenced;
+	ListCell *cell;
+
+	myself.classId = ConstraintRelationId;
+	myself.objectId = constrOid;
+	myself.objectSubId = 0;
+
+	foreach (cell, info.dependencies)
+	{
+		referenced.classId = RelationRelationId;
+		referenced.objectId = lfirst_oid(cell);
+		referenced.objectSubId = 0;
+		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
+	}
+
+	test_assertion_expr(assertion_name, ccsrc);
+
+	ObjectAddressSet(address, ConstraintRelationId, constrOid);
+
+	return address;
+}
+
+
+ObjectAddress
+RenameAssertion(RenameStmt *stmt)
+{
+	Oid           assertionOid;
+	ObjectAddress address;
+	Relation      rel;
+	HeapTuple     tuple;
+	Form_pg_constraint con;
+	AclResult     aclresult;
+
+	List *oldName = castNode(List, stmt->object);
+	char *newName = stmt->newname;
+
+	rel = heap_open(ConstraintRelationId, RowExclusiveLock);
+	assertionOid = get_assertion_oid(oldName, false);
+
+	tuple = SearchSysCache1(CONSTROID, ObjectIdGetDatum(assertionOid));
+	if (!HeapTupleIsValid(tuple))
+		elog(ERROR, "cache lookup failed for constraint %u",
+			 assertionOid);
+	con = (Form_pg_constraint) GETSTRUCT(tuple);
+
+	if (!pg_constraint_ownercheck(assertionOid, GetUserId()))
+		aclcheck_error(ACLCHECK_NOT_OWNER, OBJECT_CONVERSION,
+					   NameListToString(oldName));
+
+	aclresult = pg_namespace_aclcheck(con->connamespace, GetUserId(), ACL_CREATE);
+	if (aclresult != ACLCHECK_OK)
+		aclcheck_error(aclresult, OBJECT_SCHEMA,
+					   get_namespace_name(con->connamespace));
+
+	ReleaseSysCache(tuple);
+	RenameConstraintById(assertionOid, newName);
+	ObjectAddressSet(address, ConstraintRelationId, assertionOid);
+	heap_close(rel, NoLock);
+
+	return address;
+}
diff --git a/src/backend/commands/event_trigger.c b/src/backend/commands/event_trigger.c
index eecc85d14e..ae8b919ffe 100644
--- a/src/backend/commands/event_trigger.c
+++ b/src/backend/commands/event_trigger.c
@@ -88,6 +88,7 @@ typedef enum
 static event_trigger_support_data event_trigger_support[] = {
 	{"ACCESS METHOD", true},
 	{"AGGREGATE", true},
+	{"ASSERTION", true},
 	{"CAST", true},
 	{"CONSTRAINT", true},
 	{"COLLATION", true},
@@ -1103,6 +1104,7 @@ EventTriggerSupportsObjectType(ObjectType obtype)
 			return false;
 		case OBJECT_ACCESS_METHOD:
 		case OBJECT_AGGREGATE:
+		case OBJECT_ASSERTION:
 		case OBJECT_AMOP:
 		case OBJECT_AMPROC:
 		case OBJECT_ATTRIBUTE:
@@ -2214,6 +2216,8 @@ stringify_grant_objtype(ObjectType objtype)
 {
 	switch (objtype)
 	{
+		case OBJECT_ASSERTION:
+			return "ASSERTION";
 		case OBJECT_COLUMN:
 			return "COLUMN";
 		case OBJECT_TABLE:
@@ -2296,6 +2300,8 @@ stringify_adefprivs_objtype(ObjectType objtype)
 {
 	switch (objtype)
 	{
+		case OBJECT_ASSERTION:
+			return "ASSERTIONS";
 		case OBJECT_COLUMN:
 			return "COLUMNS";
 		case OBJECT_TABLE:
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 7c045a7afe..35ed7a503b 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -4358,6 +4358,17 @@ _copyCreateSchemaStmt(const CreateSchemaStmt *from)
 	return newnode;
 }
 
+static CreateAssertionStmt *
+_copyCreateAssertionStmt(const CreateAssertionStmt *from)
+{
+	CreateAssertionStmt *newnode = makeNode(CreateAssertionStmt);
+
+	COPY_NODE_FIELD(assertion_name);
+	COPY_NODE_FIELD(constraint);
+
+	return newnode;
+}
+
 static CreateConversionStmt *
 _copyCreateConversionStmt(const CreateConversionStmt *from)
 {
@@ -5433,6 +5444,9 @@ copyObjectImpl(const void *from)
 		case T_CreateSchemaStmt:
 			retval = _copyCreateSchemaStmt(from);
 			break;
+		case T_CreateAssertionStmt:
+			retval = _copyCreateAssertionStmt(from);
+			break;
 		case T_CreateConversionStmt:
 			retval = _copyCreateConversionStmt(from);
 			break;
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 6a971d0141..b69ed08c88 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -2112,6 +2112,15 @@ _equalCreateSchemaStmt(const CreateSchemaStmt *a, const CreateSchemaStmt *b)
 	return true;
 }
 
+static bool
+_equalCreateAssertionStmt(const CreateAssertionStmt *a, const CreateAssertionStmt *b)
+{
+	COMPARE_NODE_FIELD(assertion_name);
+	COMPARE_NODE_FIELD(constraint);
+
+	return true;
+}
+
 static bool
 _equalCreateConversionStmt(const CreateConversionStmt *a, const CreateConversionStmt *b)
 {
@@ -3510,6 +3519,9 @@ equal(const void *a, const void *b)
 		case T_CreateSchemaStmt:
 			retval = _equalCreateSchemaStmt(a, b);
 			break;
+		case T_CreateAssertionStmt:
+			retval = _equalCreateAssertionStmt(a, b);
+			break;
 		case T_CreateConversionStmt:
 			retval = _equalCreateConversionStmt(a, b);
 			break;
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 5a36367446..3dab57f478 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -259,11 +259,11 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 		CreateOpFamilyStmt AlterOpFamilyStmt CreatePLangStmt
 		CreateSchemaStmt CreateSeqStmt CreateStmt CreateStatsStmt CreateTableSpaceStmt
 		CreateFdwStmt CreateForeignServerStmt CreateForeignTableStmt
-		CreateAssertStmt CreateTransformStmt CreateTrigStmt CreateEventTrigStmt
+		CreateAssertionStmt CreateTransformStmt CreateTrigStmt CreateEventTrigStmt
 		CreateUserStmt CreateUserMappingStmt CreateRoleStmt CreatePolicyStmt
 		CreatedbStmt DeclareCursorStmt DefineStmt DeleteStmt DiscardStmt DoStmt
 		DropOpClassStmt DropOpFamilyStmt DropPLangStmt DropStmt
-		DropAssertStmt DropCastStmt DropRoleStmt
+		DropCastStmt DropRoleStmt
 		DropdbStmt DropTableSpaceStmt
 		DropTransformStmt
 		DropUserMappingStmt ExplainStmt FetchStmt
@@ -860,7 +860,7 @@ stmt :
 			| CopyStmt
 			| CreateAmStmt
 			| CreateAsStmt
-			| CreateAssertStmt
+			| CreateAssertionStmt
 			| CreateCastStmt
 			| CreateConversionStmt
 			| CreateDomainStmt
@@ -896,7 +896,6 @@ stmt :
 			| DeleteStmt
 			| DiscardStmt
 			| DoStmt
-			| DropAssertStmt
 			| DropCastStmt
 			| DropOpClassStmt
 			| DropOpFamilyStmt
@@ -5636,45 +5635,28 @@ enable_trigger:
  *
  *		QUERIES :
  *				CREATE ASSERTION ...
- *				DROP ASSERTION ...
  *
  *****************************************************************************/
 
-CreateAssertStmt:
-			CREATE ASSERTION name CHECK '(' a_expr ')'
+CreateAssertionStmt:
+			CREATE ASSERTION any_name CHECK '(' a_expr ')'
 			ConstraintAttributeSpec
 				{
-					CreateTrigStmt *n = makeNode(CreateTrigStmt);
-					n->trigname = $3;
-					n->args = list_make1($6);
-					n->isconstraint  = true;
-					processCASbits($8, @8, "ASSERTION",
-								   &n->deferrable, &n->initdeferred, NULL,
-								   NULL, yyscanner);
-
-					ereport(ERROR,
-							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-							 errmsg("CREATE ASSERTION is not yet implemented")));
-
-					$$ = (Node *)n;
-				}
-		;
-
-DropAssertStmt:
-			DROP ASSERTION name opt_drop_behavior
-				{
-					DropStmt *n = makeNode(DropStmt);
-					n->objects = NIL;
-					n->behavior = $4;
-					n->removeType = OBJECT_TRIGGER; /* XXX */
-					ereport(ERROR,
-							(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-							 errmsg("DROP ASSERTION is not yet implemented")));
-					$$ = (Node *) n;
+					CreateAssertionStmt *n = makeNode(CreateAssertionStmt);
+					Constraint *c = makeNode(Constraint);
+					c->contype = CONSTR_CHECK;
+					c->location = @4;
+					c->raw_expr = $6;
+					c->cooked_expr = NULL;
+ 					processCASbits($8, @8, "ASSERTION",
+								   &c->deferrable, &c->initdeferred, NULL,
+ 								   NULL, yyscanner);
+					n->assertion_name = $3;
+					n->constraint = c;
+ 					$$ = (Node *)n;
 				}
 		;
 
-
 /*****************************************************************************
  *
  *		QUERY :
@@ -6328,6 +6310,7 @@ drop_type_any_name:
 			| MATERIALIZED VIEW						{ $$ = OBJECT_MATVIEW; }
 			| INDEX									{ $$ = OBJECT_INDEX; }
 			| FOREIGN TABLE							{ $$ = OBJECT_FOREIGN_TABLE; }
+			| ASSERTION								{ $$ = OBJECT_ASSERTION; }
 			| COLLATION								{ $$ = OBJECT_COLLATION; }
 			| CONVERSION_P							{ $$ = OBJECT_CONVERSION; }
 			| STATISTICS							{ $$ = OBJECT_STATISTIC_EXT; }
@@ -6597,6 +6580,7 @@ comment_type_any_name:
 			| TABLE								{ $$ = OBJECT_TABLE; }
 			| VIEW								{ $$ = OBJECT_VIEW; }
 			| MATERIALIZED VIEW					{ $$ = OBJECT_MATVIEW; }
+			| ASSERTION							{ $$ = OBJECT_ASSERTION; }
 			| COLLATION							{ $$ = OBJECT_COLLATION; }
 			| CONVERSION_P						{ $$ = OBJECT_CONVERSION; }
 			| FOREIGN TABLE						{ $$ = OBJECT_FOREIGN_TABLE; }
@@ -8459,6 +8443,15 @@ RenameStmt: ALTER AGGREGATE aggregate_with_argtypes RENAME TO name
 					n->missing_ok = false;
 					$$ = (Node *)n;
 				}
+			| ALTER ASSERTION any_name RENAME TO name
+				{
+					RenameStmt *n = makeNode(RenameStmt);
+					n->renameType = OBJECT_ASSERTION;
+					n->object = (Node *) $3;
+					n->newname = $6;
+					n->missing_ok = false;
+					$$ = (Node *)n;
+				}
 			| ALTER COLLATION any_name RENAME TO name
 				{
 					RenameStmt *n = makeNode(RenameStmt);
@@ -9043,6 +9036,15 @@ AlterObjectSchemaStmt:
 					n->missing_ok = false;
 					$$ = (Node *)n;
 				}
+			| ALTER ASSERTION any_name SET SCHEMA name
+				{
+					AlterObjectSchemaStmt *n = makeNode(AlterObjectSchemaStmt);
+					n->objectType = OBJECT_ASSERTION;
+					n->object = (Node *) $3;
+					n->newschema = $6;
+					n->missing_ok = false;
+					$$ = (Node *)n;
+				}
 			| ALTER COLLATION any_name SET SCHEMA name
 				{
 					AlterObjectSchemaStmt *n = makeNode(AlterObjectSchemaStmt);
@@ -9328,6 +9330,14 @@ AlterOwnerStmt: ALTER AGGREGATE aggregate_with_argtypes OWNER TO RoleSpec
 					n->newowner = $6;
 					$$ = (Node *)n;
 				}
+			| ALTER ASSERTION any_name OWNER TO RoleSpec
+				{
+					AlterOwnerStmt *n = makeNode(AlterOwnerStmt);
+					n->objectType = OBJECT_ASSERTION;
+					n->object = (Node *) $3;
+					n->newowner = $6;
+					$$ = (Node *)n;
+				}
 			| ALTER COLLATION any_name OWNER TO RoleSpec
 				{
 					AlterOwnerStmt *n = makeNode(AlterOwnerStmt);
diff --git a/src/backend/parser/parse_agg.c b/src/backend/parser/parse_agg.c
index 61727e1d71..09126a050d 100644
--- a/src/backend/parser/parse_agg.c
+++ b/src/backend/parser/parse_agg.c
@@ -457,6 +457,7 @@ check_agglevels_and_constraints(ParseState *pstate, Node *expr)
 			break;
 		case EXPR_KIND_CHECK_CONSTRAINT:
 		case EXPR_KIND_DOMAIN_CHECK:
+		case EXPR_KIND_ASSERTION_CHECK:
 			if (isAgg)
 				err = _("aggregate functions are not allowed in check constraints");
 			else
@@ -875,6 +876,7 @@ transformWindowFuncCall(ParseState *pstate, WindowFunc *wfunc,
 			break;
 		case EXPR_KIND_CHECK_CONSTRAINT:
 		case EXPR_KIND_DOMAIN_CHECK:
+		case EXPR_KIND_ASSERTION_CHECK:
 			err = _("window functions are not allowed in check constraints");
 			break;
 		case EXPR_KIND_COLUMN_DEFAULT:
diff --git a/src/backend/parser/parse_expr.c b/src/backend/parser/parse_expr.c
index 385e54a9b6..1933a615bf 100644
--- a/src/backend/parser/parse_expr.c
+++ b/src/backend/parser/parse_expr.c
@@ -1818,6 +1818,7 @@ transformSubLink(ParseState *pstate, SubLink *sublink)
 		case EXPR_KIND_RETURNING:
 		case EXPR_KIND_VALUES:
 		case EXPR_KIND_VALUES_SINGLE:
+		case EXPR_KIND_ASSERTION_CHECK:
 			/* okay */
 			break;
 		case EXPR_KIND_CHECK_CONSTRAINT:
@@ -3457,6 +3458,7 @@ ParseExprKindName(ParseExprKind exprKind)
 			return "VALUES";
 		case EXPR_KIND_CHECK_CONSTRAINT:
 		case EXPR_KIND_DOMAIN_CHECK:
+		case EXPR_KIND_ASSERTION_CHECK:
 			return "CHECK";
 		case EXPR_KIND_COLUMN_DEFAULT:
 		case EXPR_KIND_FUNCTION_DEFAULT:
diff --git a/src/backend/parser/parse_func.c b/src/backend/parser/parse_func.c
index ea5d5212b4..8193b7da37 100644
--- a/src/backend/parser/parse_func.c
+++ b/src/backend/parser/parse_func.c
@@ -2277,6 +2277,10 @@ check_srf_call_placement(ParseState *pstate, Node *last_srf, int location)
 			/* okay, since we process this like a SELECT tlist */
 			pstate->p_hasTargetSRFs = true;
 			break;
+		case EXPR_KIND_ASSERTION_CHECK:
+			/* okay */
+			pstate->p_hasTargetSRFs = true;
+			break;
 		case EXPR_KIND_CHECK_CONSTRAINT:
 		case EXPR_KIND_DOMAIN_CHECK:
 			err = _("set-returning functions are not allowed in check constraints");
diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c
index 287addf429..22997dfd0b 100644
--- a/src/backend/tcop/utility.c
+++ b/src/backend/tcop/utility.c
@@ -30,6 +30,7 @@
 #include "commands/cluster.h"
 #include "commands/comment.h"
 #include "commands/collationcmds.h"
+#include "commands/constraint.h"
 #include "commands/conversioncmds.h"
 #include "commands/copy.h"
 #include "commands/createas.h"
@@ -161,6 +162,7 @@ check_xact_readonly(Node *parsetree)
 		case T_RenameStmt:
 		case T_CommentStmt:
 		case T_DefineStmt:
+		case T_CreateAssertionStmt:
 		case T_CreateCastStmt:
 		case T_CreateEventTrigStmt:
 		case T_AlterEventTrigStmt:
@@ -1503,6 +1505,10 @@ ProcessUtilitySlow(ParseState *pstate,
 				address = DefineDomain((CreateDomainStmt *) parsetree);
 				break;
 
+			case T_CreateAssertionStmt:
+				address = CreateAssertion((CreateAssertionStmt *) parsetree);
+				break;
+
 			case T_CreateConversionStmt:
 				address = CreateConversionCommand((CreateConversionStmt *) parsetree);
 				break;
@@ -1913,6 +1919,9 @@ AlterObjectTypeCommandTag(ObjectType objtype)
 		case OBJECT_AGGREGATE:
 			tag = "ALTER AGGREGATE";
 			break;
+		case OBJECT_ASSERTION:
+			tag = "ALTER ASSERTION";
+			break;
 		case OBJECT_ATTRIBUTE:
 			tag = "ALTER TYPE";
 			break;
@@ -2251,6 +2260,9 @@ CreateCommandTag(Node *parsetree)
 				case OBJECT_DOMAIN:
 					tag = "DROP DOMAIN";
 					break;
+				case OBJECT_ASSERTION:
+					tag = "DROP ASSERTION";
+					break;
 				case OBJECT_COLLATION:
 					tag = "DROP COLLATION";
 					break;
@@ -2681,6 +2693,10 @@ CreateCommandTag(Node *parsetree)
 			tag = "REINDEX";
 			break;
 
+		case T_CreateAssertionStmt:
+			tag = "CREATE ASSERTION";
+			break;
+
 		case T_CreateConversionStmt:
 			tag = "CREATE CONVERSION";
 			break;
@@ -3281,6 +3297,10 @@ GetCommandLogLevel(Node *parsetree)
 			lev = LOGSTMT_ALL;	/* should this be DDL? */
 			break;
 
+		case T_CreateAssertionStmt:
+			lev = LOGSTMT_DDL;
+			break;
+
 		case T_CreateConversionStmt:
 			lev = LOGSTMT_DDL;
 			break;
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index bba595ad1d..6a0d6edb81 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/src/backend/utils/cache/lsyscache.c
@@ -1542,6 +1542,25 @@ get_func_retset(Oid funcid)
 	return result;
 }
 
+/*
+ * get_func_lang
+ *		Given procedure id, return the function's language id.
+ */
+Oid
+get_func_lang(Oid funcid)
+{
+	HeapTuple	tp;
+	Oid			result;
+
+	tp = SearchSysCache1(PROCOID, ObjectIdGetDatum(funcid));
+	if (!HeapTupleIsValid(tp))
+		elog(ERROR, "cache lookup failed for function %u", funcid);
+
+	result = ((Form_pg_proc) GETSTRUCT(tp))->prolang;
+	ReleaseSysCache(tp);
+	return result;
+}
+
 /*
  * func_strict
  *		Given procedure id, return the function's proisstrict flag.
diff --git a/src/bin/psql/command.c b/src/bin/psql/command.c
index 4c85f43f09..f9345997eb 100644
--- a/src/bin/psql/command.c
+++ b/src/bin/psql/command.c
@@ -785,6 +785,9 @@ exec_command_d(PsqlScanState scan_state, bool active_branch, const char *cmd)
 			case 'p':
 				success = permissionsList(pattern);
 				break;
+			case 'Q':
+				success = describeAssertions(pattern);
+				break;
 			case 'T':
 				success = describeTypes(pattern, show_verbose, show_system);
 				break;
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index 410131e5c7..4f01061948 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -140,6 +140,66 @@ describeAggregates(const char *pattern, bool verbose, bool showSystem)
 	return true;
 }
 
+/* \dA
+ * Takes an optional regexp to select particular assertions
+ */
+bool
+describeAssertions(const char *pattern)
+{
+	PQExpBufferData buf;
+	PGresult   *res;
+	printQueryOpt myopt = pset.popt;
+
+	if (pset.sversion < 90400)
+	{
+		fprintf(stderr, _("The server (version %d.%d) does not support assertions.\n"),
+				pset.sversion / 10000, (pset.sversion / 100) % 100);
+		return true;
+	}
+
+	initPQExpBuffer(&buf);
+
+	printfPQExpBuffer(&buf,
+					  "SELECT n.nspname AS \"%s\",\n"
+							  "  c.conname AS \"%s\",\n"
+							  "  pg_catalog.pg_get_constraintdef(c.oid, true) AS \"%s\",\n"
+							  "  pg_catalog.obj_description(c.oid, 'pg_constraint') AS \"%s\"\n"
+							  "FROM pg_catalog.pg_constraint c\n"
+							  "     LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.connamespace\n"
+							  "WHERE c.conrelid = 0 AND c.contypid = 0\n",
+					  gettext_noop("Schema"),
+					  gettext_noop("Name"),
+					  gettext_noop("Definition"),
+					  gettext_noop("Description"));
+
+	if (!pattern)
+		appendPQExpBuffer(&buf, "      AND n.nspname <> 'pg_catalog'\n"
+				"      AND n.nspname <> 'information_schema'\n");
+
+#if TODO
+	processSQLNamePattern(pset.db, &buf, pattern, true, false,
+						  "n.nspname", "c.conname", NULL,
+						  "pg_catalog.pg_constraint_is_visible(c.oid)");
+#endif
+
+	appendPQExpBuffer(&buf, "ORDER BY 1, 2, 3, 4;");
+
+	res = PSQLexec(buf.data);
+	termPQExpBuffer(&buf);
+	if (!res)
+		return false;
+
+	myopt.nullPrint = NULL;
+	myopt.title = _("List of assertions");
+	myopt.translate_header = true;
+
+	printQuery(res, &myopt, pset.queryFout, false, pset.logfile);
+
+	PQclear(res);
+	return true;
+}
+
+
 /*
  * \dA
  * Takes an optional regexp to select particular access methods
@@ -2518,6 +2578,38 @@ describeOneTableDetails(const char *schemaname,
 			PQclear(result);
 		}
 
+		/* print assertions referencing this table (none if no triggers) */
+		if (tableinfo.hastriggers)
+		{
+			printfPQExpBuffer(&buf,
+							  "SELECT conname,\n"
+									  "  pg_catalog.pg_get_constraintdef(c.oid, true) AS condef\n"
+									  "FROM pg_catalog.pg_constraint c\n"
+									  "WHERE c.oid IN (SELECT objid FROM pg_depend WHERE classid = 'pg_constraint'::pg_catalog.regclass AND refclassid = 'pg_class'::pg_catalog.regclass AND refobjid = '%s')\n"
+									  "  AND c.conrelid = 0 AND c.contypid = 0 AND c.contype = 'c'\n"
+									  "ORDER BY 1",
+							  oid);
+			result = PSQLexec(buf.data);
+			if (!result)
+				goto error_return;
+			else
+				tuples = PQntuples(result);
+
+			if (tuples > 0)
+			{
+				printTableAddFooter(&cont, _("Assertions:"));
+				for (i = 0; i < tuples; i++)
+				{
+					printfPQExpBuffer(&buf, "    \"%s\" %s",
+									  PQgetvalue(result, i, 0),
+									  PQgetvalue(result, i, 1));
+
+					printTableAddFooter(&cont, buf.data);
+				}
+			}
+			PQclear(result);
+		}
+
 		/* print rules */
 		if (tableinfo.hasrules && tableinfo.relkind != RELKIND_MATVIEW)
 		{
diff --git a/src/bin/psql/describe.h b/src/bin/psql/describe.h
index a4cc5efae0..7b405b65da 100644
--- a/src/bin/psql/describe.h
+++ b/src/bin/psql/describe.h
@@ -15,6 +15,9 @@ extern bool describeAggregates(const char *pattern, bool verbose, bool showSyste
 /* \dA */
 extern bool describeAccessMethods(const char *pattern, bool verbose);
 
+/* \dQ */
+extern bool describeAssertions(const char *pattern);
+
 /* \db */
 extern bool describeTablespaces(const char *pattern, bool verbose);
 
diff --git a/src/bin/psql/help.c b/src/bin/psql/help.c
index 702e742af4..9deabd195f 100644
--- a/src/bin/psql/help.c
+++ b/src/bin/psql/help.c
@@ -223,6 +223,7 @@ slashUsage(unsigned short int pager)
 	fprintf(output, _("  \\d[S+]                 list tables, views, and sequences\n"));
 	fprintf(output, _("  \\d[S+]  NAME           describe table, view, sequence, or index\n"));
 	fprintf(output, _("  \\da[S]  [PATTERN]      list aggregates\n"));
+	fprintf(output, _("  \\dQ     [PATTERN]      list assertions\n"));
 	fprintf(output, _("  \\dA[+]  [PATTERN]      list access methods\n"));
 	fprintf(output, _("  \\db[+]  [PATTERN]      list tablespaces\n"));
 	fprintf(output, _("  \\dc[S+] [PATTERN]      list conversions\n"));
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index b431efc983..b44632d5b8 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -424,6 +424,24 @@ static const SchemaQuery Query_for_list_of_aggregates[] = {
 	}
 };
 
+static const SchemaQuery Query_for_list_of_assertions = {
+	/* min_server_version */
+	0,
+	/* catname */
+	"pg_catalog.pg_constraint c",
+	/* selcondition */
+	"(c.conrelid = 0 AND c.contypid = 0)",
+	/* viscondition */
+	"TRUE", //TODO: "pg_catalog.pg_constraint_is_visible(c.oid)",
+	/* namespace */
+	"c.connamespace",
+	/* result */
+	"pg_catalog.quote_ident(c.conname)",
+	/* qualresult */
+	NULL
+};
+
+
 static const SchemaQuery Query_for_list_of_datatypes = {
 	/* min_server_version */
 	0,
@@ -1192,6 +1210,7 @@ typedef struct
 static const pgsql_thing_t words_after_create[] = {
 	{"ACCESS METHOD", NULL, NULL, NULL, THING_NO_ALTER},
 	{"AGGREGATE", NULL, NULL, Query_for_list_of_aggregates},
+	{"ASSERTION", NULL, NULL, &Query_for_list_of_assertions},
 	{"CAST", NULL, NULL, NULL}, /* Casts have complex structures for names, so
 								 * skip it */
 	{"COLLATION", "SELECT pg_catalog.quote_ident(collname) FROM pg_catalog.pg_collation WHERE collencoding IN (-1, pg_catalog.pg_char_to_encoding(pg_catalog.getdatabaseencoding())) AND substring(pg_catalog.quote_ident(collname),1,%d)='%s'"},
@@ -1618,7 +1637,7 @@ psql_completion(const char *text, int start, int end)
 		"\\a",
 		"\\connect", "\\conninfo", "\\C", "\\cd", "\\copy",
 		"\\copyright", "\\crosstabview",
-		"\\d", "\\da", "\\dA", "\\db", "\\dc", "\\dC", "\\dd", "\\ddp", "\\dD",
+		"\\d", "\\da", "\\dA", "\\dQ", "\\db", "\\dc", "\\dC", "\\dd", "\\ddp", "\\dD",
 		"\\des", "\\det", "\\deu", "\\dew", "\\dE", "\\df",
 		"\\dF", "\\dFd", "\\dFp", "\\dFt", "\\dg", "\\di", "\\dl", "\\dL",
 		"\\dm", "\\dn", "\\do", "\\dO", "\\dp",
@@ -1769,6 +1788,11 @@ psql_completion(const char *text, int start, int end)
 	else if (Matches3("ALTER", "SCHEMA", MatchAny))
 		COMPLETE_WITH_LIST2("OWNER TO", "RENAME TO");
 
+	// TODO ASSERTION
+
+	else if (Matches3("ALTER", "ASSERTION", MatchAny))
+		COMPLETE_WITH_CONST("RENAME TO ");
+
 	/* ALTER COLLATION <name> */
 	else if (Matches3("ALTER", "COLLATION", MatchAny))
 		COMPLETE_WITH_LIST3("OWNER TO", "RENAME TO", "SET SCHEMA");
@@ -2897,7 +2921,7 @@ psql_completion(const char *text, int start, int end)
 /* DROP */
 	/* Complete DROP object with CASCADE / RESTRICT */
 	else if (Matches3("DROP",
-					  "COLLATION|CONVERSION|DOMAIN|EXTENSION|LANGUAGE|PUBLICATION|SCHEMA|SEQUENCE|SERVER|SUBSCRIPTION|STATISTICS|TABLE|TYPE|VIEW",
+					  "ASSERTION|COLLATION|CONVERSION|DOMAIN|EXTENSION|LANGUAGE|PUBLICATION|SCHEMA|SEQUENCE|SERVER|SUBSCRIPTION|STATISTICS|TABLE|TYPE|VIEW",
 					  MatchAny) ||
 			 Matches4("DROP", "ACCESS", "METHOD", MatchAny) ||
 			 (Matches4("DROP", "AGGREGATE|FUNCTION|PROCEDURE|ROUTINE", MatchAny, MatchAny) &&
@@ -3633,6 +3657,8 @@ psql_completion(const char *text, int start, int end)
 	}
 	else if (TailMatchesCS1("\\da*"))
 		COMPLETE_WITH_VERSIONED_SCHEMA_QUERY(Query_for_list_of_aggregates, NULL);
+	else if (TailMatchesCS1("\\dQ*"))
+		COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_assertions, NULL);
 	else if (TailMatchesCS1("\\dA*"))
 		COMPLETE_WITH_QUERY(Query_for_list_of_access_methods);
 	else if (TailMatchesCS1("\\db*"))
diff --git a/src/include/catalog/namespace.h b/src/include/catalog/namespace.h
index 7991de5e21..5b5c21f976 100644
--- a/src/include/catalog/namespace.h
+++ b/src/include/catalog/namespace.h
@@ -151,6 +151,7 @@ extern bool OverrideSearchPathMatchesCurrent(OverrideSearchPath *path);
 extern void PushOverrideSearchPath(OverrideSearchPath *newpath);
 extern void PopOverrideSearchPath(void);
 
+extern Oid	get_assertion_oid(List *name, bool missing_ok);
 extern Oid	get_collation_oid(List *collname, bool missing_ok);
 extern Oid	get_conversion_oid(List *conname, bool missing_ok);
 extern Oid	FindDefaultConversionProc(int32 for_encoding, int32 to_encoding);
diff --git a/src/include/catalog/pg_constraint.h b/src/include/catalog/pg_constraint.h
index 7c1c0e1db8..038ff60116 100644
--- a/src/include/catalog/pg_constraint.h
+++ b/src/include/catalog/pg_constraint.h
@@ -58,8 +58,7 @@ CATALOG(pg_constraint,2606,ConstraintRelationId)
 	 * contypid links to the pg_type row for a domain if this is a domain
 	 * constraint.  Otherwise it's 0.
 	 *
-	 * For SQL-style global ASSERTIONs, both conrelid and contypid would be
-	 * zero. This is not presently supported, however.
+	 * For SQL-style global ASSERTIONs, both conrelid and contypid are zero.
 	 */
 	Oid			contypid;		/* domain this constraint constrains */
 
@@ -184,7 +183,7 @@ typedef enum ConstraintCategory
 {
 	CONSTRAINT_RELATION,
 	CONSTRAINT_DOMAIN,
-	CONSTRAINT_ASSERTION		/* for future expansion */
+	CONSTRAINT_ASSERTION
 } ConstraintCategory;
 
 /*
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 66c6c224a8..30c4d74421 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -3711,6 +3711,10 @@
   proname => 'unique_key_recheck', provolatile => 'v', prorettype => 'trigger',
   proargtypes => '', prosrc => 'unique_key_recheck' },
 
+{ oid => '3996', descr => 'assertion constraint check',
+  proname => 'assertion_check', provolatile => 'v', prorettype => 'trigger',
+  proargtypes => '', prosrc => 'assertion_check' },
+
 # Generic referential integrity constraint triggers
 { oid => '1644', descr => 'referential integrity FOREIGN KEY ... REFERENCES',
   proname => 'RI_FKey_check_ins', provolatile => 'v', prorettype => 'trigger',
diff --git a/src/include/commands/constraint.h b/src/include/commands/constraint.h
new file mode 100644
index 0000000000..98aa8f996e
--- /dev/null
+++ b/src/include/commands/constraint.h
@@ -0,0 +1,10 @@
+#ifndef CONSTRAINT_H
+#define CONSTRAINT_H
+
+#include "catalog/objectaddress.h"
+#include "nodes/parsenodes.h"
+
+extern ObjectAddress CreateAssertion(CreateAssertionStmt *stmt);
+extern ObjectAddress RenameAssertion(RenameStmt *stmt);
+
+#endif
\ No newline at end of file
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index adb159a6da..e5dd5d1618 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -418,6 +418,7 @@ typedef enum NodeTag
 	T_DropSubscriptionStmt,
 	T_CreateStatsStmt,
 	T_AlterCollationStmt,
+	T_CreateAssertionStmt,
 	T_CallStmt,
 
 	/*
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 6390f7e8c1..389cf6331c 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -1637,6 +1637,7 @@ typedef enum ObjectType
 	OBJECT_AGGREGATE,
 	OBJECT_AMOP,
 	OBJECT_AMPROC,
+	OBJECT_ASSERTION,
 	OBJECT_ATTRIBUTE,			/* type's attribute, when distinct from column */
 	OBJECT_CAST,
 	OBJECT_COLUMN,
@@ -3290,6 +3291,16 @@ typedef struct ReindexStmt
 	int			options;		/* Reindex options flags */
 } ReindexStmt;
 
+/* ----------------------
+ *      CREATE ASSERTION Statement
+ */
+typedef struct CreateAssertionStmt
+{
+	NodeTag		type;
+	List    	*assertion_name;
+	Constraint	*constraint;
+} CreateAssertionStmt;
+
 /* ----------------------
  *		CREATE CONVERSION Statement
  * ----------------------
diff --git a/src/include/parser/parse_node.h b/src/include/parser/parse_node.h
index 0230543810..54a6b114ff 100644
--- a/src/include/parser/parse_node.h
+++ b/src/include/parser/parse_node.h
@@ -60,6 +60,7 @@ typedef enum ParseExprKind
 	EXPR_KIND_VALUES_SINGLE,	/* single-row VALUES (in INSERT only) */
 	EXPR_KIND_CHECK_CONSTRAINT, /* CHECK constraint for a table */
 	EXPR_KIND_DOMAIN_CHECK,		/* CHECK constraint for a domain */
+	EXPR_KIND_ASSERTION_CHECK,	/* CHECK constraint for an assertion */
 	EXPR_KIND_COLUMN_DEFAULT,	/* default value for a table column */
 	EXPR_KIND_FUNCTION_DEFAULT, /* default parameter value for function */
 	EXPR_KIND_INDEX_EXPRESSION, /* index expression */
diff --git a/src/include/utils/acl.h b/src/include/utils/acl.h
index f4d4be8d0d..2c10dd082f 100644
--- a/src/include/utils/acl.h
+++ b/src/include/utils/acl.h
@@ -295,6 +295,7 @@ extern bool pg_opclass_ownercheck(Oid opc_oid, Oid roleid);
 extern bool pg_opfamily_ownercheck(Oid opf_oid, Oid roleid);
 extern bool pg_database_ownercheck(Oid db_oid, Oid roleid);
 extern bool pg_collation_ownercheck(Oid coll_oid, Oid roleid);
+extern bool pg_constraint_ownercheck(Oid constr_oid, Oid roleid);
 extern bool pg_conversion_ownercheck(Oid conv_oid, Oid roleid);
 extern bool pg_ts_dict_ownercheck(Oid dict_oid, Oid roleid);
 extern bool pg_ts_config_ownercheck(Oid cfg_oid, Oid roleid);
diff --git a/src/include/utils/lsyscache.h b/src/include/utils/lsyscache.h
index e55ea4035b..f618270bc8 100644
--- a/src/include/utils/lsyscache.h
+++ b/src/include/utils/lsyscache.h
@@ -114,6 +114,7 @@ extern int	get_func_nargs(Oid funcid);
 extern Oid	get_func_signature(Oid funcid, Oid **argtypes, int *nargs);
 extern Oid	get_func_variadictype(Oid funcid);
 extern bool get_func_retset(Oid funcid);
+extern Oid  get_func_lang(Oid funcid);
 extern bool func_strict(Oid funcid);
 extern char func_volatile(Oid funcid);
 extern char func_parallel(Oid funcid);
diff --git a/src/test/regress/expected/assertions.out b/src/test/regress/expected/assertions.out
new file mode 100644
index 0000000000..7fc0d710a3
--- /dev/null
+++ b/src/test/regress/expected/assertions.out
@@ -0,0 +1,779 @@
+BEGIN TRANSACTION;
+--
+-- Create some helper views and functions to allow us to more easily
+-- assert which operations will cause an assertion to be checked.
+--
+CREATE OR REPLACE VIEW invalidating_operation
+  (assertion_name,
+   relation_name,
+   operation)
+AS
+SELECT c.conname,
+       cl.relname,
+       v.operation
+  FROM pg_trigger t
+  JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+  JOIN pg_proc p ON (t.tgfoid = p.oid)
+  JOIN pg_class cl ON (t.tgrelid = cl.oid)
+  JOIN (VALUES ('INSERT', 1<<2),
+               ('DELETE', 1<<3|1<<5),
+               ('UPDATE', 1<<4))
+    AS v(operation, mask) ON ((v.mask & tgtype) > 0)
+ WHERE t.tgisinternal
+   AND p.proname = 'assertion_check';
+CREATE OR REPLACE VIEW invalidating_by_update_of_column
+  (assertion_name,
+   relation_name,
+   column_name)
+AS
+SELECT c.conname,
+       cl.relname,
+       a.attname
+  FROM pg_trigger t INNER JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+                    INNER JOIN pg_proc p ON (t.tgfoid = p.oid)
+                    INNER JOIN pg_class cl ON (t.tgrelid = cl.oid)
+                    CROSS JOIN LATERAL UNNEST(t.tgattr) AS co(n)
+                    INNER JOIN pg_attribute a ON (a.attrelid = cl.oid AND attnum = co.n)
+ WHERE t.tgisinternal
+   AND p.proname = 'assertion_check'
+   AND (tgtype & (1 << 4)) > 0;
+CREATE OR REPLACE VIEW invalidating_summary
+  (assertion_name,
+   operations)
+AS
+SELECT assertion_name,
+       string_agg(operation, ' ' ORDER BY operation)
+  FROM (SELECT assertion_name,
+               operation ||'('|| string_agg(relation_name, ', ' ORDER BY relation_name) ||')'
+          FROM invalidating_operation
+         WHERE operation <> 'UPDATE'
+         GROUP BY assertion_name,
+                  operation
+         UNION
+        SELECT assertion_name,
+               operation ||'('|| string_agg(relation_name ||'.'|| column_name, ', ' ORDER BY relation_name, column_name) ||')'
+          FROM invalidating_by_update_of_column JOIN invalidating_operation USING (assertion_name, relation_name)
+         WHERE operation = 'UPDATE'
+         GROUP BY assertion_name,
+                  operation)
+    AS v(assertion_name, operation)
+ GROUP BY assertion_name;
+CREATE OR REPLACE FUNCTION have_identical_invalidating_operations
+  (a text, b text)
+RETURNS TABLE (predicate text, correct text)
+AS $$
+  SELECT 'assertion "'|| a ||'" has identical invalidating operations to assertion "'|| b ||'"',
+         CASE WHEN
+           NOT EXISTS (SELECT relation_name, operation
+                         FROM invalidating_operation
+                        WHERE assertion_name = a
+                       EXCEPT 
+                       SELECT relation_name, operation
+                         FROM invalidating_operation
+                        WHERE assertion_name = b) AND
+           NOT EXISTS (SELECT relation_name, column_name
+                         FROM invalidating_by_update_of_column
+                        WHERE assertion_name = a
+                       EXCEPT
+                       SELECT relation_name, column_name
+                         FROM invalidating_by_update_of_column
+                        WHERE assertion_name = b) THEN 'YES'
+                                                  ELSE 'NO' END
+$$ LANGUAGE SQL;
+COMMIT;
+BEGIN TRANSACTION;
+--
+-- Perform some basic sanity checking on creating assertions
+--
+CREATE TABLE test1 (a int, b text);
+CREATE ASSERTION foo CHECK (1 < 2);
+CREATE ASSERTION a2 CHECK ((SELECT count(*) FROM test1) < 5);
+DELETE FROM test1;
+INSERT INTO test1 VALUES (1, 'one');
+INSERT INTO test1 VALUES (2, 'two');
+INSERT INTO test1 VALUES (3, 'three');
+INSERT INTO test1 VALUES (4, 'four');
+SAVEPOINT pre_insert_too_many;
+INSERT INTO test1 VALUES (5, 'five');
+ERROR:  assertion "a2" violated
+ROLLBACK TO SAVEPOINT pre_insert_too_many;
+SELECT constraint_schema,
+       constraint_name
+  FROM information_schema.assertions
+ ORDER BY 1, 2;
+ constraint_schema | constraint_name 
+-------------------+-----------------
+ public            | a2
+ public            | foo
+(2 rows)
+
+\dQ
+                        List of assertions
+ Schema | Name |             Definition             | Description 
+--------+------+------------------------------------+-------------
+ public | a2   | CHECK ((( SELECT count(*) AS count+| 
+        |      |    FROM test1)) < 5)               | 
+ public | foo  | CHECK (1 < 2)                      | 
+(2 rows)
+
+ALTER ASSERTION a2 RENAME TO a3;
+SAVEPOINT pre_rename_foo;
+ALTER ASSERTION foo RENAME TO a3; -- fails
+ERROR:  assertion "a3" already exists
+ROLLBACK TO SAVEPOINT pre_rename_foo;
+DROP ASSERTION foo;
+SAVEPOINT pre_drop_test1;
+DROP TABLE test1; -- fails
+ERROR:  cannot drop table test1 because other objects depend on it
+DETAIL:  constraint a3 depends on table test1
+HINT:  Use DROP ... CASCADE to drop the dependent objects too.
+ROLLBACK TO SAVEPOINT pre_drop_test1;
+DROP TABLE test1 CASCADE;
+NOTICE:  drop cascades to constraint a3
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving various operators, functions and casts
+-- 
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+INSERT INTO t (n, p) VALUES (20, TRUE);
+CREATE ASSERTION is_distinct_from CHECK (10 IS DISTINCT FROM (SELECT MIN(n) FROM t));
+CREATE ASSERTION is_not_distinct_from CHECK (20 IS NOT DISTINCT FROM (SELECT MIN(n) FROM t));
+CREATE ASSERTION null_if CHECK (NULLIF((SELECT BOOL_AND(p) FROM t), FALSE));
+CREATE ASSERTION coerce_to_boolean_from_min CHECK (CAST((SELECT MIN(n) FROM t) AS BOOLEAN));
+CREATE ASSERTION coerce_to_boolean_from_bool_and CHECK (CAST((SELECT BOOL_AND(p) FROM t) AS BOOLEAN));
+CREATE ASSERTION coerce_to_boolean_from_boolean CHECK (CAST((SELECT TRUE FROM t) AS BOOLEAN));
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving function calls
+--
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL, d DATE NOT NULL);
+CREATE FUNCTION f(n INTEGER) RETURNS INTEGER
+AS $$
+  SELECT n * 2
+$$ LANGUAGE SQL;
+CREATE FUNCTION r(n INTEGER) RETURNS TABLE (m INTEGER )
+AS $$
+  SELECT m
+    FROM t
+   WHERE n > r.n
+$$ LANGUAGE SQL;
+CREATE ASSERTION age_of_d_in_t CHECK (
+  NOT EXISTS (
+    SELECT FROM t
+     WHERE AGE(DATE '01-01-2018') > INTERVAL '10 days' -- AGE(DATE) is built-in SQL
+  )
+);
+CREATE ASSERTION use_f CHECK (f(0) = 0);
+CREATE ASSERTION use_f_in_predicate CHECK (NOT EXISTS (SELECT FROM t WHERE f(n) = 20));
+CREATE ASSERTION use_f_in_target CHECK (NOT EXISTS (SELECT f(n) FROM t));
+CREATE ASSERTION use_r_in_from CHECK (NOT EXISTS (SELECT FROM r(100)));
+CREATE ASSERTION use_r_in_target CHECK (NOT EXISTS (SELECT r(100)));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (COALESCE(operations, 'NONE') = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('age_of_d_in_t',      'INSERT(t)'),
+       ('use_f',              'NONE'),
+       ('use_f_in_predicate', 'INSERT(t) UPDATE(t.n)'),
+       ('use_f_in_target',    'INSERT(t)'),
+       ('use_r_in_from',      'INSERT(t) UPDATE(t.m, t.n)'), -- TODO should _from and _target be the same?
+       ('use_r_in_target',    'INSERT(t) UPDATE(t.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+   assertion_name   |           actual           |          expected          | correct 
+--------------------+----------------------------+----------------------------+---------
+ age_of_d_in_t      | INSERT(t)                  | INSERT(t)                  | YES
+ use_f              | NONE                       | NONE                       | YES
+ use_f_in_predicate | INSERT(t) UPDATE(t.n)      | INSERT(t) UPDATE(t.n)      | YES
+ use_f_in_target    | INSERT(t)                  | INSERT(t)                  | YES
+ use_r_in_from      | INSERT(t) UPDATE(t.m, t.n) | INSERT(t) UPDATE(t.m, t.n) | YES
+ use_r_in_target    | INSERT(t) UPDATE(t.n)      | INSERT(t) UPDATE(t.n)      | YES
+(6 rows)
+
+CREATE FUNCTION g(n INTEGER) RETURNS INTEGER
+AS $$
+BEGIN
+  RETURN n * 2;
+END;
+$$ LANGUAGE PLPGSQL;
+-- Use of functions other than internal or those implemented in SQL are illegal
+CREATE ASSERTION use_g_in_from CHECK (NOT EXISTS (SELECT FROM g(100))); -- fails
+ERROR:  function "g" uses unsupported language "plpgsql"
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving EXISTS and NOT EXISTS
+--
+CREATE TABLE r (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+CREATE TABLE t1 (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+CREATE TABLE t2 (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+INSERT INTO r (n) VALUES (1);
+INSERT INTO t (n, m) VALUES (0, 0);
+INSERT INTO t1 (n, m) VALUES (0, 0);
+INSERT INTO t2 (n, m) VALUES (0, 0);
+CREATE ASSERTION exists_no_predicate CHECK (
+  EXISTS (SELECT FROM r)
+);
+CREATE ASSERTION exists_with_predicate CHECK (
+  EXISTS (SELECT FROM r WHERE n > 0)
+);
+CREATE ASSERTION not_exists_no_predicate CHECK (
+  NOT EXISTS (SELECT FROM s)
+);
+CREATE ASSERTION not_exists_with_predicate CHECK (
+  NOT EXISTS (SELECT FROM r WHERE n < 1)
+);
+CREATE ASSERTION direct_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t WHERE m = 0)
+);
+-- TODO These can be optimised, at least if the set operation is UNION.
+CREATE ASSERTION except_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t1 WHERE m = 0 EXCEPT SELECT n FROM t2 WHERE m = 1)
+);
+CREATE ASSERTION intersect_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t1 WHERE m = 0 INTERSECT SELECT n FROM t2 WHERE m = 0)
+);
+CREATE ASSERTION union_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t1 WHERE m = 0 UNION SELECT n FROM t2 WHERE m = 0)
+);
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('exists_no_predicate',            'DELETE(r)'),
+       ('exists_with_predicate',          'DELETE(r) UPDATE(r.n)'),
+       ('not_exists_no_predicate',        'INSERT(s)'),
+       ('not_exists_with_predicate',      'INSERT(r) UPDATE(r.n)'),
+       ('direct_subject_of_an_exists',    'DELETE(t) UPDATE(t.m)'),
+       ('except_subject_of_an_exists',    'DELETE(t1) INSERT(t2) UPDATE(t1.m, t1.n, t2.m, t2.n)'),
+       ('intersect_subject_of_an_exists', 'DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)'),
+       ('union_subject_of_an_exists',     'DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+         assertion_name         |                        actual                        |                       expected                       | correct 
+--------------------------------+------------------------------------------------------+------------------------------------------------------+---------
+ direct_subject_of_an_exists    | DELETE(t) UPDATE(t.m)                                | DELETE(t) UPDATE(t.m)                                | YES
+ except_subject_of_an_exists    | DELETE(t1) INSERT(t2) UPDATE(t1.m, t1.n, t2.m, t2.n) | DELETE(t1) INSERT(t2) UPDATE(t1.m, t1.n, t2.m, t2.n) | YES
+ exists_no_predicate            | DELETE(r)                                            | DELETE(r)                                            | YES
+ exists_with_predicate          | DELETE(r) UPDATE(r.n)                                | DELETE(r) UPDATE(r.n)                                | YES
+ intersect_subject_of_an_exists | DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)        | DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)        | YES
+ not_exists_no_predicate        | INSERT(s)                                            | INSERT(s)                                            | YES
+ not_exists_with_predicate      | INSERT(r) UPDATE(r.n)                                | INSERT(r) UPDATE(r.n)                                | YES
+ union_subject_of_an_exists     | DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)        | DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)        | YES
+(8 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving NOT
+--
+CREATE TABLE r (p BOOLEAN NOT NULL PRIMARY KEY);
+INSERT INTO r (p) VALUES (TRUE);
+CREATE ASSERTION a CHECK (EXISTS (SELECT FROM r WHERE p));
+CREATE ASSERTION b CHECK (NOT EXISTS (SELECT FROM r WHERE NOT p));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('a', 'DELETE(r) UPDATE(r.p)'),
+       ('b', 'INSERT(r) UPDATE(r.p)')) -- NOT(x) and x have opposite invalidating operations
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name |        actual         |       expected        | correct 
+----------------+-----------------------+-----------------------+---------
+ a              | DELETE(r) UPDATE(r.p) | DELETE(r) UPDATE(r.p) | YES
+ b              | INSERT(r) UPDATE(r.p) | INSERT(r) UPDATE(r.p) | YES
+(2 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving set operations INTERSECT, UNION, and EXCEPT
+--
+CREATE TABLE r (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY);
+INSERT INTO t (n) VALUES (0);
+CREATE ASSERTION except_operands CHECK (NOT EXISTS (SELECT FROM r EXCEPT SELECT FROM s));
+CREATE ASSERTION intersect_operands CHECK (NOT EXISTS (SELECT FROM r INTERSECT SELECT FROM s));
+CREATE ASSERTION union_operands CHECK (EXISTS (SELECT FROM s UNION SELECT FROM t));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('except_operands',    'DELETE(s) INSERT(r)'),
+       ('intersect_operands', 'INSERT(r, s)'),
+       ('union_operands',     'DELETE(s, t)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+   assertion_name   |       actual        |      expected       | correct 
+--------------------+---------------------+---------------------+---------
+ except_operands    | DELETE(s) INSERT(r) | DELETE(s) INSERT(r) | YES
+ intersect_operands | INSERT(r, s)        | INSERT(r, s)        | YES
+ union_operands     | DELETE(s, t)        | DELETE(s, t)        | YES
+(3 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving COUNT aggregations
+--
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+INSERT INTO s VALUES (1, 2);
+CREATE ASSERTION ge_all_count CHECK (1 >= ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION ge_any_count CHECK (1 >= ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION ge_count     CHECK (1 >=     (SELECT COUNT(*) FROM s));
+CREATE ASSERTION gt_all_count CHECK (2 >  ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION gt_any_count CHECK (2 >  ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION gt_count     CHECK (2 >      (SELECT COUNT(*) FROM s));
+CREATE ASSERTION le_all_count CHECK (1 <= ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION le_any_count CHECK (0 <= ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION le_count     CHECK (0 <=     (SELECT COUNT(*) FROM s));
+CREATE ASSERTION lt_all_count CHECK (0 <  ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION lt_any_count CHECK (0 <  ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION lt_count     CHECK (0 <      (SELECT COUNT(*) FROM s));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('ge_all_count', 'INSERT(s)'),
+       ('ge_any_count', 'INSERT(s)'),
+       ('ge_count',     'INSERT(s)'),
+       ('gt_all_count', 'INSERT(s)'),
+       ('gt_any_count', 'INSERT(s)'),
+       ('gt_count',     'INSERT(s)'),
+       ('le_all_count', 'DELETE(s)'),
+       ('le_any_count', 'DELETE(s)'),
+       ('le_count',     'DELETE(s)'),
+       ('lt_all_count', 'DELETE(s)'),
+       ('lt_any_count', 'DELETE(s)'),
+       ('lt_count',     'DELETE(s)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name |  actual   | expected  | correct 
+----------------+-----------+-----------+---------
+ ge_all_count   | INSERT(s) | INSERT(s) | YES
+ ge_any_count   | INSERT(s) | INSERT(s) | YES
+ ge_count       | INSERT(s) | INSERT(s) | YES
+ gt_all_count   | INSERT(s) | INSERT(s) | YES
+ gt_any_count   | INSERT(s) | INSERT(s) | YES
+ gt_count       | INSERT(s) | INSERT(s) | YES
+ le_all_count   | DELETE(s) | DELETE(s) | YES
+ le_any_count   | DELETE(s) | DELETE(s) | YES
+ le_count       | DELETE(s) | DELETE(s) | YES
+ lt_all_count   | DELETE(s) | DELETE(s) | YES
+ lt_any_count   | DELETE(s) | DELETE(s) | YES
+ lt_count       | DELETE(s) | DELETE(s) | YES
+(12 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving MIN aggregations
+--
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+INSERT INTO s VALUES (1, 2);
+CREATE ASSERTION ge_any_min CHECK (1 >= ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION ge_all_min CHECK (1 >= ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION ge_min     CHECK (1 >=     (SELECT MIN(n) FROM s));
+CREATE ASSERTION gt_any_min CHECK (2 >  ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION gt_all_min CHECK (2 >  ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION gt_min     CHECK (2 >      (SELECT MIN(n) FROM s));
+CREATE ASSERTION le_any_min CHECK (0 <= ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION le_all_min CHECK (0 <= ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION le_min     CHECK (0 <=     (SELECT MIN(n) FROM s));
+CREATE ASSERTION lt_any_min CHECK (0 <  ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION lt_all_min CHECK (0 <  ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION lt_min     CHECK (0 <      (SELECT MIN(n) FROM s));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('ge_all_min', 'DELETE(s) UPDATE(s.n)'),
+       ('ge_any_min', 'DELETE(s) UPDATE(s.n)'),
+       ('ge_min',     'DELETE(s) UPDATE(s.n)'),
+       ('gt_all_min', 'DELETE(s) UPDATE(s.n)'),
+       ('gt_any_min', 'DELETE(s) UPDATE(s.n)'),
+       ('gt_min',     'DELETE(s) UPDATE(s.n)'),
+       ('le_all_min', 'INSERT(s) UPDATE(s.n)'),
+       ('le_any_min', 'INSERT(s) UPDATE(s.n)'),
+       ('le_min',     'INSERT(s) UPDATE(s.n)'),
+       ('lt_all_min', 'INSERT(s) UPDATE(s.n)'),
+       ('lt_any_min', 'INSERT(s) UPDATE(s.n)'),
+       ('lt_min',     'INSERT(s) UPDATE(s.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name |        actual         |       expected        | correct 
+----------------+-----------------------+-----------------------+---------
+ ge_all_min     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ ge_any_min     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ ge_min         | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ gt_all_min     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ gt_any_min     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ gt_min         | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ le_all_min     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ le_any_min     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ le_min         | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ lt_all_min     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ lt_any_min     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ lt_min         | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+(12 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving MAX aggregations
+--
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+INSERT INTO s VALUES (1, 2);
+CREATE ASSERTION ge_any_max CHECK (1 >= ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION ge_all_max CHECK (1 >= ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION ge_max     CHECK (1 >=     (SELECT MAX(n) FROM s));
+CREATE ASSERTION gt_all_max CHECK (2 >  ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION gt_any_max CHECK (2 >  ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION gt_max     CHECK (2 >      (SELECT MAX(n) FROM s));
+CREATE ASSERTION le_all_max CHECK (0 <= ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION le_any_max CHECK (0 <= ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION le_max     CHECK (0 <=     (SELECT MAX(n) FROM s));
+CREATE ASSERTION lt_all_max CHECK (0 <  ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION lt_any_max CHECK (0 <  ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION lt_max     CHECK (0 <      (SELECT MAX(n) FROM s));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('ge_all_max', 'INSERT(s) UPDATE(s.n)'),
+       ('ge_any_max', 'INSERT(s) UPDATE(s.n)'),
+       ('ge_max',     'INSERT(s) UPDATE(s.n)'),
+       ('gt_all_max', 'INSERT(s) UPDATE(s.n)'),
+       ('gt_any_max', 'INSERT(s) UPDATE(s.n)'),
+       ('gt_max',     'INSERT(s) UPDATE(s.n)'),
+       ('le_all_max', 'DELETE(s) UPDATE(s.n)'),
+       ('le_any_max', 'DELETE(s) UPDATE(s.n)'),
+       ('le_max',     'DELETE(s) UPDATE(s.n)'),
+       ('lt_all_max', 'DELETE(s) UPDATE(s.n)'),
+       ('lt_any_max', 'DELETE(s) UPDATE(s.n)'),
+       ('lt_max',     'DELETE(s) UPDATE(s.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name |        actual         |       expected        | correct 
+----------------+-----------------------+-----------------------+---------
+ ge_all_max     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ ge_any_max     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ ge_max         | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ gt_all_max     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ gt_any_max     | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ gt_max         | INSERT(s) UPDATE(s.n) | INSERT(s) UPDATE(s.n) | YES
+ le_all_max     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ le_any_max     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ le_max         | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ lt_all_max     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ lt_any_max     | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+ lt_max         | DELETE(s) UPDATE(s.n) | DELETE(s) UPDATE(s.n) | YES
+(12 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving BOOL_AND aggregations
+--
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+INSERT INTO t (n, p) VALUES (0, TRUE);
+CREATE ASSERTION eq_bool_and     CHECK (TRUE  =      (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION eq_any_bool_and CHECK (TRUE  =  ANY (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION eq_all_bool_and CHECK (TRUE  =  ALL (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION ne_bool_and     CHECK (FALSE <>     (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION ne_any_bool_and CHECK (FALSE <> ANY (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION ne_all_bool_and CHECK (FALSE <> ALL (SELECT BOOL_AND(p) FROM t));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('eq_all_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('eq_any_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('eq_bool_and',     'INSERT(t) UPDATE(t.p)'),
+       ('ne_all_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('ne_any_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('ne_bool_and',     'INSERT(t) UPDATE(t.p)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name  |        actual         |       expected        | correct 
+-----------------+-----------------------+-----------------------+---------
+ eq_all_bool_and | INSERT(t) UPDATE(t.p) | INSERT(t) UPDATE(t.p) | YES
+ eq_any_bool_and | INSERT(t) UPDATE(t.p) | INSERT(t) UPDATE(t.p) | YES
+ eq_bool_and     | INSERT(t) UPDATE(t.p) | INSERT(t) UPDATE(t.p) | YES
+ ne_all_bool_and | INSERT(t) UPDATE(t.p) | INSERT(t) UPDATE(t.p) | YES
+ ne_any_bool_and | INSERT(t) UPDATE(t.p) | INSERT(t) UPDATE(t.p) | YES
+ ne_bool_and     | INSERT(t) UPDATE(t.p) | INSERT(t) UPDATE(t.p) | YES
+(6 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving BOOL_OR aggregations
+--
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+INSERT INTO t (n, p) VALUES (0, TRUE);
+CREATE ASSERTION eq_bool_or     CHECK (TRUE  =      (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION eq_any_bool_or CHECK (TRUE  =  ANY (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION eq_all_bool_or CHECK (TRUE  =  ALL (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION ne_bool_or     CHECK (FALSE <>     (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION ne_any_bool_or CHECK (FALSE <> ANY (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION ne_all_bool_or CHECK (FALSE <> ALL (SELECT BOOL_OR(p) FROM t));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('eq_all_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('eq_any_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('eq_bool_or',     'DELETE(t) UPDATE(t.p)'),
+       ('ne_all_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('ne_any_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('ne_bool_or',     'DELETE(t) UPDATE(t.p)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name |        actual         |       expected        | correct 
+----------------+-----------------------+-----------------------+---------
+ eq_all_bool_or | DELETE(t) UPDATE(t.p) | DELETE(t) UPDATE(t.p) | YES
+ eq_any_bool_or | DELETE(t) UPDATE(t.p) | DELETE(t) UPDATE(t.p) | YES
+ eq_bool_or     | DELETE(t) UPDATE(t.p) | DELETE(t) UPDATE(t.p) | YES
+ ne_all_bool_or | DELETE(t) UPDATE(t.p) | DELETE(t) UPDATE(t.p) | YES
+ ne_any_bool_or | DELETE(t) UPDATE(t.p) | DELETE(t) UPDATE(t.p) | YES
+ ne_bool_or     | DELETE(t) UPDATE(t.p) | DELETE(t) UPDATE(t.p) | YES
+(6 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions involving window functions
+--
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+-- Regular window function
+CREATE ASSERTION alternate_p CHECK (
+  NOT EXISTS (
+    SELECT FROM (
+      SELECT LAG(p, 1, NOT p) OVER n <> p
+         AND LEAD(p, 1, NOT p) OVER n <> p
+        FROM t
+      WINDOW n AS (ORDER BY n)
+    ) AS v(q)
+    WHERE NOT q
+  )
+);
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('alternate_p', 'DELETE(t) INSERT(t) UPDATE(t.n, t.p)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name |                actual                |               expected               | correct 
+----------------+--------------------------------------+--------------------------------------+---------
+ alternate_p    | DELETE(t) INSERT(t) UPDATE(t.n, t.p) | DELETE(t) INSERT(t) UPDATE(t.n, t.p) | YES
+(1 row)
+
+INSERT INTO t (n, p) VALUES (10, TRUE);
+INSERT INTO t (n, p) VALUES (20, FALSE);
+INSERT INTO t (n, p) VALUES (30, TRUE);
+SAVEPOINT pre_insert;
+INSERT INTO t (n, p) VALUES (40, TRUE);
+ERROR:  assertion "alternate_p" violated
+ROLLBACK TO SAVEPOINT pre_insert;
+SAVEPOINT pre_delete;
+DELETE FROM t WHERE n = 20;
+ERROR:  assertion "alternate_p" violated
+ROLLBACK TO SAVEPOINT pre_delete;
+SAVEPOINT pre_update;
+UPDATE t SET p = NOT p WHERE n = 20;
+ERROR:  assertion "alternate_p" violated
+ROLLBACK TO SAVEPOINT pre_update;
+DROP ASSERTION alternate_p;
+-- Aggregate function over a window
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+INSERT INTO s (n, m)
+SELECT n, (2 * n)
+  FROM GENERATE_SERIES(0, 9) AS ns(n);
+CREATE ASSERTION max_over_window CHECK ((10, 20) > ALL (SELECT n, MAX(m) OVER (ORDER BY n) FROM s));
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('max_over_window', 'INSERT(s) UPDATE(s.m, s.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+ assertion_name  |           actual           |          expected          | correct 
+-----------------+----------------------------+----------------------------+---------
+ max_over_window | INSERT(s) UPDATE(s.m, s.n) | INSERT(s) UPDATE(s.m, s.n) | YES
+(1 row)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- Expressions containing a comparison should have the same invalidating
+-- operations as an expression containing the inverse comparison operation
+-- and where the operands have been switched
+--
+CREATE TABLE r (n INTEGER NOT NULL PRIMARY KEY);
+INSERT INTO r (n) VALUES (9);
+-- ">" and "<" are opposites
+CREATE ASSERTION a CHECK (10 > (SELECT MIN(n) FROM r));
+CREATE ASSERTION b CHECK ((SELECT MIN(n) FROM r) < 10);
+-- "<" and ">" are opposites
+CREATE ASSERTION c CHECK (8 < (SELECT MIN(n) FROM r));
+CREATE ASSERTION d CHECK ((SELECT MIN(n) FROM r) > 8);
+-- ">=" and "<=" are opposites
+CREATE ASSERTION e CHECK (9 >= (SELECT MIN(n) FROM r));
+CREATE ASSERTION f CHECK ((SELECT MIN(n) FROM r) <= 9);
+-- "<=" and ">=" are opposites
+CREATE ASSERTION g CHECK (9 <= (SELECT MIN(n) FROM r));
+CREATE ASSERTION h CHECK ((SELECT MIN(n) FROM r) >= 9);
+SELECT (test).predicate, (test).correct
+  FROM (
+VALUES ('a', 'b'),
+       ('c', 'd'),
+       ('e', 'f'),
+       ('g', 'h'))
+    AS v(a, b)
+ CROSS JOIN LATERAL (SELECT have_identical_invalidating_operations(v.a, v.b))
+    AS w(test)
+ ORDER BY 1, 2;
+                              predicate                               | correct 
+----------------------------------------------------------------------+---------
+ assertion "a" has identical invalidating operations to assertion "b" | YES
+ assertion "c" has identical invalidating operations to assertion "d" | YES
+ assertion "e" has identical invalidating operations to assertion "f" | YES
+ assertion "g" has identical invalidating operations to assertion "h" | YES
+(4 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+--
+-- The INFORMATION_SCHEMA should contain the correct information
+--
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+CREATE ASSERTION a CHECK (NOT EXISTS (SELECT FROM t WHERE p));
+SELECT predicate,
+       CASE WHEN
+         truth THEN 'YES'
+               ELSE 'NO'
+       END AS correct
+  FROM ( 
+VALUES ('INFORMATION_SCHEMA.CONSTRAINT_TABLE_USAGE contains only the correct tables',
+        EXISTS (
+          SELECT FROM information_schema.constraint_table_usage
+           WHERE (constraint_name, table_name) = ('a', 't'))
+        AND NOT EXISTS (
+          SELECT FROM information_schema.constraint_table_usage
+           WHERE constraint_name = 'a'
+             AND table_name <> 't')),
+       ('INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE contains only the correct columns (t.p)',
+        EXISTS (
+          SELECT FROM information_schema.constraint_column_usage
+           WHERE (constraint_name, table_name, column_name) = ('a', 't', 'p'))
+        AND NOT EXISTS (
+          SELECT FROM information_schema.constraint_column_usage
+           WHERE constraint_name ='a'
+             AND (table_name, column_name) <> ('t', 'p'))),
+       ('INFORMATION_SCHEMA.ASSERTIONS contains only the correct assertions',
+        EXISTS (
+          SELECT FROM information_schema.assertions
+           WHERE constraint_name = 'a')
+        AND NOT EXISTS (
+          SELECT FROM information_schema.assertions
+           WHERE constraint_name <> 'a')))
+    AS v(predicate, truth);
+                                     predicate                                      | correct 
+------------------------------------------------------------------------------------+---------
+ INFORMATION_SCHEMA.CONSTRAINT_TABLE_USAGE contains only the correct tables         | YES
+ INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE contains only the correct columns (t.p) | YES
+ INFORMATION_SCHEMA.ASSERTIONS contains only the correct assertions                 | YES
+(3 rows)
+
+ROLLBACK;
+BEGIN TRANSACTION;
+-- TODO This needs rethinking
+/*
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+CREATE VIEW v AS SELECT * FROM s INNER JOIN t USING (n);
+
+CREATE ASSERTION a CHECK (NOT EXISTS (SELECT FROM v));
+
+-- we should depend on the view not the tables
+SELECT OK(depends_on('a', 'v'),
+          'Assertion depends upon the view v it references');
+SELECT OK(NOT depends_on('a', 's'),
+          'Assertion does not depend upon the table s referenced in the view v');
+SELECT OK(NOT depends_on('a', 't'),
+          'Assertion does not depend upon the table t referenced in the view v');
+
+-- we should trigger on the tables and not the view
+SELECT OK(EXISTS(SELECT FROM assertion_check_operation
+                  WHERE (assertion_name, relation_name) = ('a', 's')),
+          'Assertion is checked on modifications to table s');
+SELECT OK(EXISTS(SELECT FROM assertion_check_operation
+                  WHERE (assertion_name, relation_name) = ('a', 't')),
+          'Assertion is checked on modifications to table t');
+SELECT OK(NOT EXISTS(SELECT FROM assertion_check_operation
+                      WHERE (assertion_name, relation_name) = ('a', 'v')),
+          'Assertion is not checked on modifications to view v');
+*/
+ROLLBACK;
+-- TODO test commonalities between count, min, max, etc, for optimisations
+-- TODO ensure window function aggregates are treated the same as regular aggregates
+-- TODO ensure that conflicting aggregate functions are not incorrectly optimised
+-- TODO ensure that recorded dependencies are correct (traversal into functions and views)
+BEGIN TRANSACTION;
+DROP FUNCTION have_identical_invalidating_operations;
+DROP VIEW invalidating_summary;
+DROP VIEW invalidating_by_update_of_column;
+DROP VIEW invalidating_operation;
+COMMIT;
diff --git a/src/test/regress/parallel_schedule b/src/test/regress/parallel_schedule
index 16f979c8d9..084e76c1d0 100644
--- a/src/test/regress/parallel_schedule
+++ b/src/test/regress/parallel_schedule
@@ -60,7 +60,7 @@ test: create_index create_view index_including
 # ----------
 # Another group of parallel tests
 # ----------
-test: create_aggregate create_function_3 create_cast constraints triggers inherit create_table_like typed_table vacuum drop_if_exists updatable_views rolenames roleattributes create_am hash_func
+test: create_aggregate create_function_3 create_cast constraints triggers inherit create_table_like typed_table vacuum drop_if_exists updatable_views rolenames roleattributes create_am assertions hash_func
 
 # ----------
 # sanity_check does a vacuum, affecting the sort order of SELECT *
diff --git a/src/test/regress/serial_schedule b/src/test/regress/serial_schedule
index 42632be675..f413969b6d 100644
--- a/src/test/regress/serial_schedule
+++ b/src/test/regress/serial_schedule
@@ -58,6 +58,7 @@ test: create_function_1
 test: create_type
 test: create_table
 test: create_function_2
+test: assertions
 test: copy
 test: copyselect
 test: copydml
diff --git a/src/test/regress/sql/assertions.sql b/src/test/regress/sql/assertions.sql
new file mode 100644
index 0000000000..f270698da1
--- /dev/null
+++ b/src/test/regress/sql/assertions.sql
@@ -0,0 +1,775 @@
+
+BEGIN TRANSACTION;
+
+--
+-- Create some helper views and functions to allow us to more easily
+-- assert which operations will cause an assertion to be checked.
+--
+
+CREATE OR REPLACE VIEW invalidating_operation
+  (assertion_name,
+   relation_name,
+   operation)
+AS
+SELECT c.conname,
+       cl.relname,
+       v.operation
+  FROM pg_trigger t
+  JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+  JOIN pg_proc p ON (t.tgfoid = p.oid)
+  JOIN pg_class cl ON (t.tgrelid = cl.oid)
+  JOIN (VALUES ('INSERT', 1<<2),
+               ('DELETE', 1<<3|1<<5),
+               ('UPDATE', 1<<4))
+    AS v(operation, mask) ON ((v.mask & tgtype) > 0)
+ WHERE t.tgisinternal
+   AND p.proname = 'assertion_check';
+
+CREATE OR REPLACE VIEW invalidating_by_update_of_column
+  (assertion_name,
+   relation_name,
+   column_name)
+AS
+SELECT c.conname,
+       cl.relname,
+       a.attname
+  FROM pg_trigger t INNER JOIN pg_constraint c ON (t.tgconstraint = c.oid)
+                    INNER JOIN pg_proc p ON (t.tgfoid = p.oid)
+                    INNER JOIN pg_class cl ON (t.tgrelid = cl.oid)
+                    CROSS JOIN LATERAL UNNEST(t.tgattr) AS co(n)
+                    INNER JOIN pg_attribute a ON (a.attrelid = cl.oid AND attnum = co.n)
+ WHERE t.tgisinternal
+   AND p.proname = 'assertion_check'
+   AND (tgtype & (1 << 4)) > 0;
+
+CREATE OR REPLACE VIEW invalidating_summary
+  (assertion_name,
+   operations)
+AS
+SELECT assertion_name,
+       string_agg(operation, ' ' ORDER BY operation)
+  FROM (SELECT assertion_name,
+               operation ||'('|| string_agg(relation_name, ', ' ORDER BY relation_name) ||')'
+          FROM invalidating_operation
+         WHERE operation <> 'UPDATE'
+         GROUP BY assertion_name,
+                  operation
+         UNION
+        SELECT assertion_name,
+               operation ||'('|| string_agg(relation_name ||'.'|| column_name, ', ' ORDER BY relation_name, column_name) ||')'
+          FROM invalidating_by_update_of_column JOIN invalidating_operation USING (assertion_name, relation_name)
+         WHERE operation = 'UPDATE'
+         GROUP BY assertion_name,
+                  operation)
+    AS v(assertion_name, operation)
+ GROUP BY assertion_name;
+
+CREATE OR REPLACE FUNCTION have_identical_invalidating_operations
+  (a text, b text)
+RETURNS TABLE (predicate text, correct text)
+AS $$
+  SELECT 'assertion "'|| a ||'" has identical invalidating operations to assertion "'|| b ||'"',
+         CASE WHEN
+           NOT EXISTS (SELECT relation_name, operation
+                         FROM invalidating_operation
+                        WHERE assertion_name = a
+                       EXCEPT 
+                       SELECT relation_name, operation
+                         FROM invalidating_operation
+                        WHERE assertion_name = b) AND
+           NOT EXISTS (SELECT relation_name, column_name
+                         FROM invalidating_by_update_of_column
+                        WHERE assertion_name = a
+                       EXCEPT
+                       SELECT relation_name, column_name
+                         FROM invalidating_by_update_of_column
+                        WHERE assertion_name = b) THEN 'YES'
+                                                  ELSE 'NO' END
+$$ LANGUAGE SQL;
+
+COMMIT;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Perform some basic sanity checking on creating assertions
+--
+
+CREATE TABLE test1 (a int, b text);
+
+CREATE ASSERTION foo CHECK (1 < 2);
+CREATE ASSERTION a2 CHECK ((SELECT count(*) FROM test1) < 5);
+
+DELETE FROM test1;
+INSERT INTO test1 VALUES (1, 'one');
+INSERT INTO test1 VALUES (2, 'two');
+INSERT INTO test1 VALUES (3, 'three');
+INSERT INTO test1 VALUES (4, 'four');
+
+SAVEPOINT pre_insert_too_many;
+INSERT INTO test1 VALUES (5, 'five');
+ROLLBACK TO SAVEPOINT pre_insert_too_many;
+
+SELECT constraint_schema,
+       constraint_name
+  FROM information_schema.assertions
+ ORDER BY 1, 2;
+
+\dQ
+
+ALTER ASSERTION a2 RENAME TO a3;
+
+SAVEPOINT pre_rename_foo;
+ALTER ASSERTION foo RENAME TO a3; -- fails
+ROLLBACK TO SAVEPOINT pre_rename_foo;
+
+DROP ASSERTION foo;
+
+SAVEPOINT pre_drop_test1;
+DROP TABLE test1; -- fails
+ROLLBACK TO SAVEPOINT pre_drop_test1;
+
+DROP TABLE test1 CASCADE;
+
+ROLLBACK;
+
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving various operators, functions and casts
+-- 
+
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+
+INSERT INTO t (n, p) VALUES (20, TRUE);
+
+CREATE ASSERTION is_distinct_from CHECK (10 IS DISTINCT FROM (SELECT MIN(n) FROM t));
+CREATE ASSERTION is_not_distinct_from CHECK (20 IS NOT DISTINCT FROM (SELECT MIN(n) FROM t));
+CREATE ASSERTION null_if CHECK (NULLIF((SELECT BOOL_AND(p) FROM t), FALSE));
+CREATE ASSERTION coerce_to_boolean_from_min CHECK (CAST((SELECT MIN(n) FROM t) AS BOOLEAN));
+CREATE ASSERTION coerce_to_boolean_from_bool_and CHECK (CAST((SELECT BOOL_AND(p) FROM t) AS BOOLEAN));
+CREATE ASSERTION coerce_to_boolean_from_boolean CHECK (CAST((SELECT TRUE FROM t) AS BOOLEAN));
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving function calls
+--
+
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL, d DATE NOT NULL);
+
+CREATE FUNCTION f(n INTEGER) RETURNS INTEGER
+AS $$
+  SELECT n * 2
+$$ LANGUAGE SQL;
+
+CREATE FUNCTION r(n INTEGER) RETURNS TABLE (m INTEGER )
+AS $$
+  SELECT m
+    FROM t
+   WHERE n > r.n
+$$ LANGUAGE SQL;
+
+CREATE ASSERTION age_of_d_in_t CHECK (
+  NOT EXISTS (
+    SELECT FROM t
+     WHERE AGE(DATE '01-01-2018') > INTERVAL '10 days' -- AGE(DATE) is built-in SQL
+  )
+);
+CREATE ASSERTION use_f CHECK (f(0) = 0);
+CREATE ASSERTION use_f_in_predicate CHECK (NOT EXISTS (SELECT FROM t WHERE f(n) = 20));
+CREATE ASSERTION use_f_in_target CHECK (NOT EXISTS (SELECT f(n) FROM t));
+CREATE ASSERTION use_r_in_from CHECK (NOT EXISTS (SELECT FROM r(100)));
+CREATE ASSERTION use_r_in_target CHECK (NOT EXISTS (SELECT r(100)));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (COALESCE(operations, 'NONE') = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('age_of_d_in_t',      'INSERT(t)'),
+       ('use_f',              'NONE'),
+       ('use_f_in_predicate', 'INSERT(t) UPDATE(t.n)'),
+       ('use_f_in_target',    'INSERT(t)'),
+       ('use_r_in_from',      'INSERT(t) UPDATE(t.m, t.n)'), -- TODO should _from and _target be the same?
+       ('use_r_in_target',    'INSERT(t) UPDATE(t.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+CREATE FUNCTION g(n INTEGER) RETURNS INTEGER
+AS $$
+BEGIN
+  RETURN n * 2;
+END;
+$$ LANGUAGE PLPGSQL;
+
+-- Use of functions other than internal or those implemented in SQL are illegal
+CREATE ASSERTION use_g_in_from CHECK (NOT EXISTS (SELECT FROM g(100))); -- fails
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving EXISTS and NOT EXISTS
+--
+
+CREATE TABLE r (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+CREATE TABLE t1 (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+CREATE TABLE t2 (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+
+INSERT INTO r (n) VALUES (1);
+INSERT INTO t (n, m) VALUES (0, 0);
+INSERT INTO t1 (n, m) VALUES (0, 0);
+INSERT INTO t2 (n, m) VALUES (0, 0);
+
+CREATE ASSERTION exists_no_predicate CHECK (
+  EXISTS (SELECT FROM r)
+);
+
+CREATE ASSERTION exists_with_predicate CHECK (
+  EXISTS (SELECT FROM r WHERE n > 0)
+);
+
+CREATE ASSERTION not_exists_no_predicate CHECK (
+  NOT EXISTS (SELECT FROM s)
+);
+
+CREATE ASSERTION not_exists_with_predicate CHECK (
+  NOT EXISTS (SELECT FROM r WHERE n < 1)
+);
+
+CREATE ASSERTION direct_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t WHERE m = 0)
+);
+
+-- TODO These can be optimised, at least if the set operation is UNION.
+CREATE ASSERTION except_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t1 WHERE m = 0 EXCEPT SELECT n FROM t2 WHERE m = 1)
+);
+
+CREATE ASSERTION intersect_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t1 WHERE m = 0 INTERSECT SELECT n FROM t2 WHERE m = 0)
+);
+
+CREATE ASSERTION union_subject_of_an_exists CHECK (
+  EXISTS (SELECT n FROM t1 WHERE m = 0 UNION SELECT n FROM t2 WHERE m = 0)
+);
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('exists_no_predicate',            'DELETE(r)'),
+       ('exists_with_predicate',          'DELETE(r) UPDATE(r.n)'),
+       ('not_exists_no_predicate',        'INSERT(s)'),
+       ('not_exists_with_predicate',      'INSERT(r) UPDATE(r.n)'),
+       ('direct_subject_of_an_exists',    'DELETE(t) UPDATE(t.m)'),
+       ('except_subject_of_an_exists',    'DELETE(t1) INSERT(t2) UPDATE(t1.m, t1.n, t2.m, t2.n)'),
+       ('intersect_subject_of_an_exists', 'DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)'),
+       ('union_subject_of_an_exists',     'DELETE(t1, t2) UPDATE(t1.m, t1.n, t2.m, t2.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving NOT
+--
+
+CREATE TABLE r (p BOOLEAN NOT NULL PRIMARY KEY);
+
+INSERT INTO r (p) VALUES (TRUE);
+
+CREATE ASSERTION a CHECK (EXISTS (SELECT FROM r WHERE p));
+CREATE ASSERTION b CHECK (NOT EXISTS (SELECT FROM r WHERE NOT p));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('a', 'DELETE(r) UPDATE(r.p)'),
+       ('b', 'INSERT(r) UPDATE(r.p)')) -- NOT(x) and x have opposite invalidating operations
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving set operations INTERSECT, UNION, and EXCEPT
+--
+
+CREATE TABLE r (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY);
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY);
+
+INSERT INTO t (n) VALUES (0);
+
+CREATE ASSERTION except_operands CHECK (NOT EXISTS (SELECT FROM r EXCEPT SELECT FROM s));
+CREATE ASSERTION intersect_operands CHECK (NOT EXISTS (SELECT FROM r INTERSECT SELECT FROM s));
+CREATE ASSERTION union_operands CHECK (EXISTS (SELECT FROM s UNION SELECT FROM t));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('except_operands',    'DELETE(s) INSERT(r)'),
+       ('intersect_operands', 'INSERT(r, s)'),
+       ('union_operands',     'DELETE(s, t)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving COUNT aggregations
+--
+
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+
+INSERT INTO s VALUES (1, 2);
+
+CREATE ASSERTION ge_all_count CHECK (1 >= ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION ge_any_count CHECK (1 >= ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION ge_count     CHECK (1 >=     (SELECT COUNT(*) FROM s));
+CREATE ASSERTION gt_all_count CHECK (2 >  ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION gt_any_count CHECK (2 >  ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION gt_count     CHECK (2 >      (SELECT COUNT(*) FROM s));
+CREATE ASSERTION le_all_count CHECK (1 <= ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION le_any_count CHECK (0 <= ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION le_count     CHECK (0 <=     (SELECT COUNT(*) FROM s));
+CREATE ASSERTION lt_all_count CHECK (0 <  ALL (SELECT COUNT(*) FROM s));
+CREATE ASSERTION lt_any_count CHECK (0 <  ANY (SELECT COUNT(*) FROM s));
+CREATE ASSERTION lt_count     CHECK (0 <      (SELECT COUNT(*) FROM s));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('ge_all_count', 'INSERT(s)'),
+       ('ge_any_count', 'INSERT(s)'),
+       ('ge_count',     'INSERT(s)'),
+       ('gt_all_count', 'INSERT(s)'),
+       ('gt_any_count', 'INSERT(s)'),
+       ('gt_count',     'INSERT(s)'),
+       ('le_all_count', 'DELETE(s)'),
+       ('le_any_count', 'DELETE(s)'),
+       ('le_count',     'DELETE(s)'),
+       ('lt_all_count', 'DELETE(s)'),
+       ('lt_any_count', 'DELETE(s)'),
+       ('lt_count',     'DELETE(s)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving MIN aggregations
+--
+
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+
+INSERT INTO s VALUES (1, 2);
+
+CREATE ASSERTION ge_any_min CHECK (1 >= ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION ge_all_min CHECK (1 >= ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION ge_min     CHECK (1 >=     (SELECT MIN(n) FROM s));
+CREATE ASSERTION gt_any_min CHECK (2 >  ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION gt_all_min CHECK (2 >  ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION gt_min     CHECK (2 >      (SELECT MIN(n) FROM s));
+CREATE ASSERTION le_any_min CHECK (0 <= ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION le_all_min CHECK (0 <= ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION le_min     CHECK (0 <=     (SELECT MIN(n) FROM s));
+CREATE ASSERTION lt_any_min CHECK (0 <  ANY (SELECT MIN(n) FROM s));
+CREATE ASSERTION lt_all_min CHECK (0 <  ALL (SELECT MIN(n) FROM s));
+CREATE ASSERTION lt_min     CHECK (0 <      (SELECT MIN(n) FROM s));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('ge_all_min', 'DELETE(s) UPDATE(s.n)'),
+       ('ge_any_min', 'DELETE(s) UPDATE(s.n)'),
+       ('ge_min',     'DELETE(s) UPDATE(s.n)'),
+       ('gt_all_min', 'DELETE(s) UPDATE(s.n)'),
+       ('gt_any_min', 'DELETE(s) UPDATE(s.n)'),
+       ('gt_min',     'DELETE(s) UPDATE(s.n)'),
+       ('le_all_min', 'INSERT(s) UPDATE(s.n)'),
+       ('le_any_min', 'INSERT(s) UPDATE(s.n)'),
+       ('le_min',     'INSERT(s) UPDATE(s.n)'),
+       ('lt_all_min', 'INSERT(s) UPDATE(s.n)'),
+       ('lt_any_min', 'INSERT(s) UPDATE(s.n)'),
+       ('lt_min',     'INSERT(s) UPDATE(s.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving MAX aggregations
+--
+
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+
+INSERT INTO s VALUES (1, 2);
+
+CREATE ASSERTION ge_any_max CHECK (1 >= ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION ge_all_max CHECK (1 >= ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION ge_max     CHECK (1 >=     (SELECT MAX(n) FROM s));
+CREATE ASSERTION gt_all_max CHECK (2 >  ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION gt_any_max CHECK (2 >  ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION gt_max     CHECK (2 >      (SELECT MAX(n) FROM s));
+CREATE ASSERTION le_all_max CHECK (0 <= ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION le_any_max CHECK (0 <= ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION le_max     CHECK (0 <=     (SELECT MAX(n) FROM s));
+CREATE ASSERTION lt_all_max CHECK (0 <  ALL (SELECT MAX(n) FROM s));
+CREATE ASSERTION lt_any_max CHECK (0 <  ANY (SELECT MAX(n) FROM s));
+CREATE ASSERTION lt_max     CHECK (0 <      (SELECT MAX(n) FROM s));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('ge_all_max', 'INSERT(s) UPDATE(s.n)'),
+       ('ge_any_max', 'INSERT(s) UPDATE(s.n)'),
+       ('ge_max',     'INSERT(s) UPDATE(s.n)'),
+       ('gt_all_max', 'INSERT(s) UPDATE(s.n)'),
+       ('gt_any_max', 'INSERT(s) UPDATE(s.n)'),
+       ('gt_max',     'INSERT(s) UPDATE(s.n)'),
+       ('le_all_max', 'DELETE(s) UPDATE(s.n)'),
+       ('le_any_max', 'DELETE(s) UPDATE(s.n)'),
+       ('le_max',     'DELETE(s) UPDATE(s.n)'),
+       ('lt_all_max', 'DELETE(s) UPDATE(s.n)'),
+       ('lt_any_max', 'DELETE(s) UPDATE(s.n)'),
+       ('lt_max',     'DELETE(s) UPDATE(s.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving BOOL_AND aggregations
+--
+
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+INSERT INTO t (n, p) VALUES (0, TRUE);
+
+CREATE ASSERTION eq_bool_and     CHECK (TRUE  =      (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION eq_any_bool_and CHECK (TRUE  =  ANY (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION eq_all_bool_and CHECK (TRUE  =  ALL (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION ne_bool_and     CHECK (FALSE <>     (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION ne_any_bool_and CHECK (FALSE <> ANY (SELECT BOOL_AND(p) FROM t));
+CREATE ASSERTION ne_all_bool_and CHECK (FALSE <> ALL (SELECT BOOL_AND(p) FROM t));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('eq_all_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('eq_any_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('eq_bool_and',     'INSERT(t) UPDATE(t.p)'),
+       ('ne_all_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('ne_any_bool_and', 'INSERT(t) UPDATE(t.p)'),
+       ('ne_bool_and',     'INSERT(t) UPDATE(t.p)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving BOOL_OR aggregations
+--
+
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+INSERT INTO t (n, p) VALUES (0, TRUE);
+
+CREATE ASSERTION eq_bool_or     CHECK (TRUE  =      (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION eq_any_bool_or CHECK (TRUE  =  ANY (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION eq_all_bool_or CHECK (TRUE  =  ALL (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION ne_bool_or     CHECK (FALSE <>     (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION ne_any_bool_or CHECK (FALSE <> ANY (SELECT BOOL_OR(p) FROM t));
+CREATE ASSERTION ne_all_bool_or CHECK (FALSE <> ALL (SELECT BOOL_OR(p) FROM t));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('eq_all_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('eq_any_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('eq_bool_or',     'DELETE(t) UPDATE(t.p)'),
+       ('ne_all_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('ne_any_bool_or', 'DELETE(t) UPDATE(t.p)'),
+       ('ne_bool_or',     'DELETE(t) UPDATE(t.p)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions involving window functions
+--
+
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+
+-- Regular window function
+CREATE ASSERTION alternate_p CHECK (
+  NOT EXISTS (
+    SELECT FROM (
+      SELECT LAG(p, 1, NOT p) OVER n <> p
+         AND LEAD(p, 1, NOT p) OVER n <> p
+        FROM t
+      WINDOW n AS (ORDER BY n)
+    ) AS v(q)
+    WHERE NOT q
+  )
+);
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('alternate_p', 'DELETE(t) INSERT(t) UPDATE(t.n, t.p)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+INSERT INTO t (n, p) VALUES (10, TRUE);
+INSERT INTO t (n, p) VALUES (20, FALSE);
+INSERT INTO t (n, p) VALUES (30, TRUE);
+
+SAVEPOINT pre_insert;
+INSERT INTO t (n, p) VALUES (40, TRUE);
+ROLLBACK TO SAVEPOINT pre_insert;
+
+SAVEPOINT pre_delete;
+DELETE FROM t WHERE n = 20;
+ROLLBACK TO SAVEPOINT pre_delete;
+
+SAVEPOINT pre_update;
+UPDATE t SET p = NOT p WHERE n = 20;
+ROLLBACK TO SAVEPOINT pre_update;
+
+DROP ASSERTION alternate_p;
+
+-- Aggregate function over a window
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+
+INSERT INTO s (n, m)
+SELECT n, (2 * n)
+  FROM GENERATE_SERIES(0, 9) AS ns(n);
+
+CREATE ASSERTION max_over_window CHECK ((10, 20) > ALL (SELECT n, MAX(m) OVER (ORDER BY n) FROM s));
+
+SELECT assertion_name,
+       COALESCE(operations, 'NONE') AS actual,
+       expected,
+       CASE WHEN (operations = expected)
+         THEN 'YES' ELSE 'NO'
+       END AS correct
+  FROM invalidating_summary FULL OUTER JOIN (
+VALUES ('max_over_window', 'INSERT(s) UPDATE(s.m, s.n)'))
+    AS v(assertion_name, expected)
+ USING (assertion_name)
+ ORDER BY assertion_name, operations;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- Expressions containing a comparison should have the same invalidating
+-- operations as an expression containing the inverse comparison operation
+-- and where the operands have been switched
+--
+
+CREATE TABLE r (n INTEGER NOT NULL PRIMARY KEY);
+
+INSERT INTO r (n) VALUES (9);
+
+-- ">" and "<" are opposites
+CREATE ASSERTION a CHECK (10 > (SELECT MIN(n) FROM r));
+CREATE ASSERTION b CHECK ((SELECT MIN(n) FROM r) < 10);
+
+-- "<" and ">" are opposites
+CREATE ASSERTION c CHECK (8 < (SELECT MIN(n) FROM r));
+CREATE ASSERTION d CHECK ((SELECT MIN(n) FROM r) > 8);
+
+-- ">=" and "<=" are opposites
+CREATE ASSERTION e CHECK (9 >= (SELECT MIN(n) FROM r));
+CREATE ASSERTION f CHECK ((SELECT MIN(n) FROM r) <= 9);
+
+-- "<=" and ">=" are opposites
+CREATE ASSERTION g CHECK (9 <= (SELECT MIN(n) FROM r));
+CREATE ASSERTION h CHECK ((SELECT MIN(n) FROM r) >= 9);
+
+SELECT (test).predicate, (test).correct
+  FROM (
+VALUES ('a', 'b'),
+       ('c', 'd'),
+       ('e', 'f'),
+       ('g', 'h'))
+    AS v(a, b)
+ CROSS JOIN LATERAL (SELECT have_identical_invalidating_operations(v.a, v.b))
+    AS w(test)
+ ORDER BY 1, 2;
+
+ROLLBACK;
+
+
+BEGIN TRANSACTION;
+
+--
+-- The INFORMATION_SCHEMA should contain the correct information
+--
+
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+CREATE ASSERTION a CHECK (NOT EXISTS (SELECT FROM t WHERE p));
+
+SELECT predicate,
+       CASE WHEN
+         truth THEN 'YES'
+               ELSE 'NO'
+       END AS correct
+  FROM ( 
+VALUES ('INFORMATION_SCHEMA.CONSTRAINT_TABLE_USAGE contains only the correct tables',
+        EXISTS (
+          SELECT FROM information_schema.constraint_table_usage
+           WHERE (constraint_name, table_name) = ('a', 't'))
+        AND NOT EXISTS (
+          SELECT FROM information_schema.constraint_table_usage
+           WHERE constraint_name = 'a'
+             AND table_name <> 't')),
+       ('INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE contains only the correct columns (t.p)',
+        EXISTS (
+          SELECT FROM information_schema.constraint_column_usage
+           WHERE (constraint_name, table_name, column_name) = ('a', 't', 'p'))
+        AND NOT EXISTS (
+          SELECT FROM information_schema.constraint_column_usage
+           WHERE constraint_name ='a'
+             AND (table_name, column_name) <> ('t', 'p'))),
+       ('INFORMATION_SCHEMA.ASSERTIONS contains only the correct assertions',
+        EXISTS (
+          SELECT FROM information_schema.assertions
+           WHERE constraint_name = 'a')
+        AND NOT EXISTS (
+          SELECT FROM information_schema.assertions
+           WHERE constraint_name <> 'a')))
+    AS v(predicate, truth);
+
+ROLLBACK;
+
+BEGIN TRANSACTION;
+-- TODO This needs rethinking
+/*
+CREATE TABLE s (n INTEGER NOT NULL PRIMARY KEY, m INTEGER NOT NULL);
+CREATE TABLE t (n INTEGER NOT NULL PRIMARY KEY, p BOOLEAN NOT NULL);
+CREATE VIEW v AS SELECT * FROM s INNER JOIN t USING (n);
+
+CREATE ASSERTION a CHECK (NOT EXISTS (SELECT FROM v));
+
+-- we should depend on the view not the tables
+SELECT OK(depends_on('a', 'v'),
+          'Assertion depends upon the view v it references');
+SELECT OK(NOT depends_on('a', 's'),
+          'Assertion does not depend upon the table s referenced in the view v');
+SELECT OK(NOT depends_on('a', 't'),
+          'Assertion does not depend upon the table t referenced in the view v');
+
+-- we should trigger on the tables and not the view
+SELECT OK(EXISTS(SELECT FROM assertion_check_operation
+                  WHERE (assertion_name, relation_name) = ('a', 's')),
+          'Assertion is checked on modifications to table s');
+SELECT OK(EXISTS(SELECT FROM assertion_check_operation
+                  WHERE (assertion_name, relation_name) = ('a', 't')),
+          'Assertion is checked on modifications to table t');
+SELECT OK(NOT EXISTS(SELECT FROM assertion_check_operation
+                      WHERE (assertion_name, relation_name) = ('a', 'v')),
+          'Assertion is not checked on modifications to view v');
+*/
+ROLLBACK;
+
+-- TODO test commonalities between count, min, max, etc, for optimisations
+-- TODO ensure window function aggregates are treated the same as regular aggregates
+-- TODO ensure that conflicting aggregate functions are not incorrectly optimised
+-- TODO ensure that recorded dependencies are correct (traversal into functions and views)
+
+BEGIN TRANSACTION;
+
+DROP FUNCTION have_identical_invalidating_operations;
+DROP VIEW invalidating_summary;
+DROP VIEW invalidating_by_update_of_column;
+DROP VIEW invalidating_operation;
+
+COMMIT;
-- 
2.15.0