Add psql command to list constraints

From ce46a3fa7252109348876ab9efff8bafcb119730 Mon Sep 17 00:00:00 2001
From: Tatsuro Yamada <yamatattsu@gmail.com>
Date: Mon, 15 Nov 2021 17:58:31 +0900
Subject: [PATCH] Add psql command to list constraints POC2

	- Add a filter by contype
	- Add pg_catalog prefix
	- Fix typo
	- Fix help message to add \dco
---
 src/bin/psql/command.c  | 19 +++++++++-
 src/bin/psql/describe.c | 98 +++++++++++++++++++++++++++++++++++++++++++++++++
 src/bin/psql/describe.h |  3 ++
 src/bin/psql/help.c     |  1 +
 4 files changed, 120 insertions(+), 1 deletion(-)

diff --git a/src/bin/psql/command.c b/src/bin/psql/command.c
index 3de9d09..92c61bc 100644
--- a/src/bin/psql/command.c
+++ b/src/bin/psql/command.c
@@ -769,7 +769,24 @@ exec_command_d(PsqlScanState scan_state, bool active_branch, const char *cmd)
 				success = describeTablespaces(pattern, show_verbose);
 				break;
 			case 'c':
-				success = listConversions(pattern, show_verbose, show_system);
+				if (strncmp(cmd, "dco", 3) == 0) /* Constraint */
+					switch (cmd[3])
+					{
+						case '\0':
+						case '+':
+						case 'S':
+						case 'c':
+						case 'f':
+						case 'p':
+						case 'u':
+						case 't':
+						case 'x':
+							success = listConstraints(&cmd[2], pattern, show_system);
+							break;
+						default:
+							status = PSQL_CMD_UNKNOWN;
+							break;
+					}
 				break;
 			case 'C':
 				success = listCasts(pattern, show_verbose);
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index ea721d9..8837626 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -18,6 +18,7 @@
 #include "catalog/pg_attribute_d.h"
 #include "catalog/pg_cast_d.h"
 #include "catalog/pg_class_d.h"
+#include "catalog/pg_constraint_d.h"
 #include "catalog/pg_default_acl_d.h"
 #include "common.h"
 #include "common/logging.h"
@@ -4816,6 +4817,103 @@ listExtendedStats(const char *pattern)
 }
 
 /*
+ * \dco
+ *
+ * Describes constraints
+ *
+ * As with \d, you can specify the kinds of constraints you want:
+ *
+ * c for check
+ * f for foreign key
+ * p for primary key
+ * t for trigger
+ * u for unique
+ * x for exclude
+ *
+ * and you can mix and match these in any order.
+ */
+bool
+listConstraints(const char *contypes, const char *pattern, bool showSystem)
+{
+	bool		showCheck = strchr(contypes, 'c') != NULL;
+	bool		showForeign = strchr(contypes, 'f') != NULL;
+	bool		showPrimary = strchr(contypes, 'p') != NULL;
+	bool		showTrigger = strchr(contypes, 't') != NULL;
+	bool		showUnique = strchr(contypes, 'u') != NULL;
+	bool		showExclude = strchr(contypes, 'x') != NULL;
+	bool		showAllkinds = false;
+	PQExpBufferData buf;
+	PGresult   *res;
+	printQueryOpt myopt = pset.popt;
+
+	/* If contype was not selected, show them all */
+	if (!(showCheck || showForeign || showPrimary || showTrigger || showUnique || showExclude))
+		showAllkinds = true;
+
+	initPQExpBuffer(&buf);
+	printfPQExpBuffer(&buf,
+					  "SELECT \n"
+					  "    n.nspname AS \"%s\", \n"
+					  "    cst.conname AS \"%s\", \n"
+					  "    pg_catalog.pg_get_constraintdef(cst.oid) AS \"%s\", \n"
+					  "    conrelid::pg_catalog.regclass AS \"%s\" \n"
+					  "FROM pg_catalog.pg_constraint cst \n"
+					  "    JOIN pg_catalog.pg_namespace n ON n.oid = cst.connamespace \n",
+					  gettext_noop("Schema"),
+					  gettext_noop("Name"),
+					  gettext_noop("Definition"),
+					  gettext_noop("Table")
+	);
+
+	if (!showSystem && !pattern)
+		appendPQExpBufferStr(&buf,
+							 "WHERE n.nspname <> 'pg_catalog' \n"
+							 "  AND n.nspname <> 'information_schema' \n");
+
+	processSQLNamePattern(pset.db, &buf, pattern,
+						  !showSystem && !pattern, false,
+						  "n.nspname", "cst.conname",
+						  NULL, "pg_catalog.pg_table_is_visible(cst.conrelid)");
+
+	if (!showAllkinds)
+	{
+		appendPQExpBufferStr(&buf, "  AND cst.contype in (");
+
+		if (showCheck)
+			appendPQExpBufferStr(&buf, CppAsString2(CONSTRAINT_CHECK) ",");
+		if (showForeign)
+			appendPQExpBufferStr(&buf, CppAsString2(CONSTRAINT_FOREIGN) ",");
+		if (showPrimary)
+			appendPQExpBufferStr(&buf, CppAsString2(CONSTRAINT_PRIMARY) ",");
+		if (showTrigger)
+			appendPQExpBufferStr(&buf, CppAsString2(CONSTRAINT_TRIGGER) ",");
+		if (showUnique)
+			appendPQExpBufferStr(&buf, CppAsString2(CONSTRAINT_UNIQUE) ",");
+		if (showExclude)
+			appendPQExpBufferStr(&buf, CppAsString2(CONSTRAINT_EXCLUSION) ",");
+
+		appendPQExpBufferStr(&buf, "''");	/* dummy */
+		appendPQExpBufferStr(&buf, ")\n");
+	}
+
+	appendPQExpBufferStr(&buf, "ORDER BY 1, 2, 3;");
+
+	res = PSQLexec(buf.data);
+	termPQExpBuffer(&buf);
+	if (!res)
+		return false;
+
+	myopt.nullPrint = NULL;
+	myopt.title = _("List of constraints");
+	myopt.translate_header = true;
+
+	printQuery(res, &myopt, pset.queryFout, false, pset.logfile);
+
+	PQclear(res);
+	return true;
+}
+
+/*
  * \dC
  *
  * Describes casts.
diff --git a/src/bin/psql/describe.h b/src/bin/psql/describe.h
index 71b320f..083ca6c 100644
--- a/src/bin/psql/describe.h
+++ b/src/bin/psql/describe.h
@@ -76,6 +76,9 @@ extern bool listDomains(const char *pattern, bool verbose, bool showSystem);
 /* \dc */
 extern bool listConversions(const char *pattern, bool verbose, bool showSystem);
 
+/* \dco */
+extern bool listConstraints(const char *contypes, const char *pattern, bool showSystem);
+
 /* \dC */
 extern bool listCasts(const char *pattern, bool verbose);
 
diff --git a/src/bin/psql/help.c b/src/bin/psql/help.c
index db12a8b..62c11c5 100644
--- a/src/bin/psql/help.c
+++ b/src/bin/psql/help.c
@@ -231,6 +231,7 @@ slashUsage(unsigned short int pager)
 	fprintf(output, _("  \\dAp[+] [AMPTRN [OPFPTRN]]   list support functions of operator families\n"));
 	fprintf(output, _("  \\db[+]  [PATTERN]      list tablespaces\n"));
 	fprintf(output, _("  \\dc[S+] [PATTERN]      list conversions\n"));
+	fprintf(output, _("  \\dco[S] [PATTERN]      list constraint\n"));
 	fprintf(output, _("  \\dC[+]  [PATTERN]      list casts\n"));
 	fprintf(output, _("  \\dd[S]  [PATTERN]      show object descriptions not displayed elsewhere\n"));
 	fprintf(output, _("  \\dD[S+] [PATTERN]      list domains\n"));
-- 
1.8.3.1

From eee92ee549e49d0b5aef438aff10236611db410e Mon Sep 17 00:00:00 2001
From: Tatsuro Yamada <yamatattsu@gmail.com>
Date: Mon, 15 Nov 2021 17:58:31 +0900
Subject: [PATCH] Add psql command to list constraints POC3

	- Fix help message s/constraint/constraints/
	- s/Exclude/Exclusion/
	- Remove unused modifier "+"
	- Add document for \dco
---
 doc/src/sgml/ref/psql-ref.sgml | 18 ++++++++
 src/bin/psql/command.c         | 18 +++++++-
 src/bin/psql/describe.c        | 98 ++++++++++++++++++++++++++++++++++++++++++
 src/bin/psql/describe.h        |  3 ++
 src/bin/psql/help.c            |  1 +
 5 files changed, 137 insertions(+), 1 deletion(-)

diff --git a/doc/src/sgml/ref/psql-ref.sgml b/doc/src/sgml/ref/psql-ref.sgml
index 48248f7..c6704d7 100644
--- a/doc/src/sgml/ref/psql-ref.sgml
+++ b/doc/src/sgml/ref/psql-ref.sgml
@@ -1388,6 +1388,24 @@ testdb=&gt;
 
 
       <varlistentry>
+        <term><literal>\dco[cfptuxS] [ <link linkend="app-psql-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
+        <listitem>
+        <para>
+        Lists constraints.
+        If <replaceable class="parameter">pattern</replaceable>
+        is specified, only entries whose name matches the pattern are listed.
+        The modifiers <literal>c</literal> (check), <literal>f</literal> (foreign key),
+        <literal>p</literal> (primary key), <literal>t</literal> (trigger), 
+        <literal>u</literal> (unique), <literal>x</literal> (exclusion) can be 
+        appended to the command, filtering the kind of constraints to list. 
+        By default, only user-created constraints are shown; supply the 
+	    <literal>S</literal> modifier to include system objects. 
+        </para>
+        </listitem>
+      </varlistentry>
+
+
+      <varlistentry>
         <term><literal>\dC[+] [ <link linkend="app-psql-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
         <listitem>
         <para>
diff --git a/src/bin/psql/command.c b/src/bin/psql/command.c
index 3de9d09..0379610 100644
--- a/src/bin/psql/command.c
+++ b/src/bin/psql/command.c
@@ -769,7 +769,23 @@ exec_command_d(PsqlScanState scan_state, bool active_branch, const char *cmd)
 				success = describeTablespaces(pattern, show_verbose);
 				break;
 			case 'c':
-				success = listConversions(pattern, show_verbose, show_system);
+				if (strncmp(cmd, "dco", 3) == 0) /* Constraint */
+					switch (cmd[3])
+					{
+						case '\0':
+						case 'S':
+						case 'c':
+						case 'f':
+						case 'p':
+						case 'u':
+						case 't':
+						case 'x':
+							success = listConstraints(&cmd[2], pattern, show_system);
+							break;
+						default:
+							status = PSQL_CMD_UNKNOWN;
+							break;
+					}
 				break;
 			case 'C':
 				success = listCasts(pattern, show_verbose);
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index ea721d9..4724d63 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -18,6 +18,7 @@
 #include "catalog/pg_attribute_d.h"
 #include "catalog/pg_cast_d.h"
 #include "catalog/pg_class_d.h"
+#include "catalog/pg_constraint_d.h"
 #include "catalog/pg_default_acl_d.h"
 #include "common.h"
 #include "common/logging.h"
@@ -4816,6 +4817,103 @@ listExtendedStats(const char *pattern)
 }
 
 /*
+ * \dco
+ *
+ * Describes constraints
+ *
+ * As with \d, you can specify the kinds of constraints you want:
+ *
+ * c for check
+ * f for foreign key
+ * p for primary key
+ * t for trigger
+ * u for unique
+ * x for exclusion
+ *
+ * and you can mix and match these in any order.
+ */
+bool
+listConstraints(const char *contypes, const char *pattern, bool showSystem)
+{
+	bool		showCheck = strchr(contypes, CONSTRAINT_CHECK) != NULL;
+	bool		showForeign = strchr(contypes, CONSTRAINT_FOREIGN) != NULL;
+	bool		showPrimary = strchr(contypes, CONSTRAINT_PRIMARY) != NULL;
+	bool		showTrigger = strchr(contypes, CONSTRAINT_TRIGGER) != NULL;
+	bool		showUnique = strchr(contypes, CONSTRAINT_UNIQUE) != NULL;
+	bool		showExclusion = strchr(contypes, CONSTRAINT_EXCLUSION) != NULL;
+	bool		showAllkinds = false;
+	PQExpBufferData buf;
+	PGresult   *res;
+	printQueryOpt myopt = pset.popt;
+
+	/* If contype was not selected, show them all */
+	if (!(showCheck || showForeign || showPrimary || showTrigger || showUnique || showExclusion))
+		showAllkinds = true;
+
+	initPQExpBuffer(&buf);
+	printfPQExpBuffer(&buf,
+					  "SELECT \n"
+					  "    n.nspname AS \"%s\", \n"
+					  "    cst.conname AS \"%s\", \n"
+					  "    pg_catalog.pg_get_constraintdef(cst.oid) AS \"%s\", \n"
+					  "    conrelid::pg_catalog.regclass AS \"%s\" \n"
+					  "FROM pg_catalog.pg_constraint cst \n"
+					  "    JOIN pg_catalog.pg_namespace n ON n.oid = cst.connamespace \n",
+					  gettext_noop("Schema"),
+					  gettext_noop("Name"),
+					  gettext_noop("Definition"),
+					  gettext_noop("Table")
+	);
+
+	if (!showSystem && !pattern)
+		appendPQExpBufferStr(&buf,
+							 "WHERE n.nspname <> 'pg_catalog' \n"
+							 "  AND n.nspname <> 'information_schema' \n");
+
+	processSQLNamePattern(pset.db, &buf, pattern,
+						  !showSystem && !pattern, false,
+						  "n.nspname", "cst.conname",
+						  NULL, "pg_catalog.pg_table_is_visible(cst.conrelid)");
+
+	if (!showAllkinds)
+	{
+		appendPQExpBufferStr(&buf, "  AND cst.contype in (");
+
+		if (showCheck)
+			appendPQExpBufferStr(&buf, CppAsString2(CONSTRAINT_CHECK) ",");
+		if (showForeign)
+			appendPQExpBufferStr(&buf, CppAsString2(CONSTRAINT_FOREIGN) ",");
+		if (showPrimary)
+			appendPQExpBufferStr(&buf, CppAsString2(CONSTRAINT_PRIMARY) ",");
+		if (showTrigger)
+			appendPQExpBufferStr(&buf, CppAsString2(CONSTRAINT_TRIGGER) ",");
+		if (showUnique)
+			appendPQExpBufferStr(&buf, CppAsString2(CONSTRAINT_UNIQUE) ",");
+		if (showExclusion)
+			appendPQExpBufferStr(&buf, CppAsString2(CONSTRAINT_EXCLUSION) ",");
+
+		appendPQExpBufferStr(&buf, "''");	/* dummy */
+		appendPQExpBufferStr(&buf, ")\n");
+	}
+
+	appendPQExpBufferStr(&buf, "ORDER BY 1, 2, 3;");
+
+	res = PSQLexec(buf.data);
+	termPQExpBuffer(&buf);
+	if (!res)
+		return false;
+
+	myopt.nullPrint = NULL;
+	myopt.title = _("List of constraints");
+	myopt.translate_header = true;
+
+	printQuery(res, &myopt, pset.queryFout, false, pset.logfile);
+
+	PQclear(res);
+	return true;
+}
+
+/*
  * \dC
  *
  * Describes casts.
diff --git a/src/bin/psql/describe.h b/src/bin/psql/describe.h
index 71b320f..083ca6c 100644
--- a/src/bin/psql/describe.h
+++ b/src/bin/psql/describe.h
@@ -76,6 +76,9 @@ extern bool listDomains(const char *pattern, bool verbose, bool showSystem);
 /* \dc */
 extern bool listConversions(const char *pattern, bool verbose, bool showSystem);
 
+/* \dco */
+extern bool listConstraints(const char *contypes, const char *pattern, bool showSystem);
+
 /* \dC */
 extern bool listCasts(const char *pattern, bool verbose);
 
diff --git a/src/bin/psql/help.c b/src/bin/psql/help.c
index db12a8b..0804b9c 100644
--- a/src/bin/psql/help.c
+++ b/src/bin/psql/help.c
@@ -231,6 +231,7 @@ slashUsage(unsigned short int pager)
 	fprintf(output, _("  \\dAp[+] [AMPTRN [OPFPTRN]]   list support functions of operator families\n"));
 	fprintf(output, _("  \\db[+]  [PATTERN]      list tablespaces\n"));
 	fprintf(output, _("  \\dc[S+] [PATTERN]      list conversions\n"));
+	fprintf(output, _("  \\dco[cfptuxS] [PATTERN] list constraints\n"));
 	fprintf(output, _("  \\dC[+]  [PATTERN]      list casts\n"));
 	fprintf(output, _("  \\dd[S]  [PATTERN]      show object descriptions not displayed elsewhere\n"));
 	fprintf(output, _("  \\dD[S+] [PATTERN]      list domains\n"));
-- 
1.8.3.1

diff --git a/doc/src/sgml/ref/psql-ref.sgml b/doc/src/sgml/ref/psql-ref.sgml
index caabb06..125ae3d 100644
--- a/doc/src/sgml/ref/psql-ref.sgml
+++ b/doc/src/sgml/ref/psql-ref.sgml
@@ -1388,6 +1388,26 @@ testdb=>
 
 
       <varlistentry>
+        <term><literal>\dco[cfptuxS+] [ <link linkend="app-psql-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
+        <listitem>
+        <para>
+        Lists constraints.
+        If <replaceable class="parameter">pattern</replaceable>
+        is specified, only entries whose name matches the pattern are listed.
+        The modifiers <literal>c</literal> (check), <literal>f</literal> (foreign key),
+        <literal>p</literal> (primary key), <literal>t</literal> (trigger), 
+        <literal>u</literal> (unique), <literal>x</literal> (exclusion) can be 
+        appended to the command, filtering the kind of constraints to list. 
+        By default, only user-created constraints are shown; supply the 
+        <literal>S</literal> modifier to include system objects. 
+        If <literal>+</literal> is appended to the command name, each object
+        is listed with its associated description.
+        </para>
+        </listitem>
+      </varlistentry>
+
+
+      <varlistentry>
         <term><literal>\dC[+] [ <link linkend="app-psql-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
         <listitem>
         <para>
diff --git a/src/bin/psql/command.c b/src/bin/psql/command.c
index 079f4a1..05ae25e 100644
--- a/src/bin/psql/command.c
+++ b/src/bin/psql/command.c
@@ -780,7 +780,26 @@ exec_command_d(PsqlScanState scan_state, bool active_branch, const char *cmd)
 				success = describeTablespaces(pattern, show_verbose);
 				break;
 			case 'c':
-				success = listConversions(pattern, show_verbose, show_system);
+				if (strncmp(cmd, "dco", 3) == 0) /* Constraint */
+					switch (cmd[3])
+					{
+						case '\0':
+						case '+':
+						case 'S':
+						case 'c':
+						case 'f':
+						case 'p':
+						case 't':
+						case 'u':
+						case 'x':
+							success = listConstraints(&cmd[3], pattern, show_verbose, show_system);
+							break;
+						default:
+							status = PSQL_CMD_UNKNOWN;
+							break;
+					}
+				else
+					success = listConversions(pattern, show_verbose, show_system);
 				break;
 			case 'C':
 				success = listCasts(pattern, show_verbose);
diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c
index 4dddf08..7acd25a 100644
--- a/src/bin/psql/describe.c
+++ b/src/bin/psql/describe.c
@@ -19,6 +19,7 @@
 #include "catalog/pg_attribute_d.h"
 #include "catalog/pg_cast_d.h"
 #include "catalog/pg_class_d.h"
+#include "catalog/pg_constraint_d.h"
 #include "catalog/pg_default_acl_d.h"
 #include "common.h"
 #include "common/logging.h"
@@ -4599,6 +4600,109 @@ listExtendedStats(const char *pattern)
 }
 
 /*
+ * \dco
+ *
+ * Describes constraints
+ *
+ * As with \d, you can specify the kinds of constraints you want:
+ *
+ * c for check
+ * f for foreign key
+ * p for primary key
+ * t for trigger
+ * u for unique
+ * x for exclusion
+ *
+ * and you can mix and match these in any order.
+ */
+bool
+listConstraints(const char *contypes, const char *pattern, bool verbose, bool showSystem)
+{
+	bool		showCheck = strchr(contypes, CONSTRAINT_CHECK) != NULL;
+	bool		showForeign = strchr(contypes, CONSTRAINT_FOREIGN) != NULL;
+	bool		showPrimary = strchr(contypes, CONSTRAINT_PRIMARY) != NULL;
+	bool		showTrigger = strchr(contypes, CONSTRAINT_TRIGGER) != NULL;
+	bool		showUnique = strchr(contypes, CONSTRAINT_UNIQUE) != NULL;
+	bool		showExclusion = strchr(contypes, CONSTRAINT_EXCLUSION) != NULL;
+	bool		showAllkinds = false;
+	PQExpBufferData buf;
+	PGresult   *res;
+	printQueryOpt myopt = pset.popt;
+
+	/* If contype was not selected, show them all */
+	if (!(showCheck || showForeign || showPrimary || showTrigger || showUnique || showExclusion))
+		showAllkinds = true;
+
+	initPQExpBuffer(&buf);
+	printfPQExpBuffer(&buf,
+					  "SELECT n.nspname AS \"%s\", \n"
+					  "       cst.conname AS \"%s\" ",
+					  gettext_noop("Schema"),
+					  gettext_noop("Name")
+	);
+
+	if (verbose)
+		appendPQExpBuffer(&buf,
+						  ",\n       pg_catalog.pg_get_constraintdef(cst.oid) AS \"%s\", \n"
+						  "       conrelid::pg_catalog.regclass AS \"%s\" ",
+						  gettext_noop("Definition"),
+						  gettext_noop("Table")
+		);
+
+	appendPQExpBufferStr(&buf,
+						 "\nFROM pg_catalog.pg_constraint cst \n"
+						 "     JOIN pg_catalog.pg_namespace n ON n.oid = cst.connamespace \n"
+	);
+
+	if (!showSystem && !pattern)
+		appendPQExpBufferStr(&buf,
+							 "WHERE n.nspname <> 'pg_catalog' \n"
+							 "  AND n.nspname <> 'information_schema' \n");
+
+	processSQLNamePattern(pset.db, &buf, pattern,
+						  !showSystem && !pattern, false,
+						  "n.nspname", "cst.conname",
+						  NULL, "pg_catalog.pg_table_is_visible(cst.conrelid)");
+
+	if (!showAllkinds)
+	{
+		appendPQExpBufferStr(&buf, "  AND cst.contype in (");
+
+		if (showCheck)
+			appendPQExpBufferStr(&buf, CppAsString2(CONSTRAINT_CHECK) ",");
+		if (showForeign)
+			appendPQExpBufferStr(&buf, CppAsString2(CONSTRAINT_FOREIGN) ",");
+		if (showPrimary)
+			appendPQExpBufferStr(&buf, CppAsString2(CONSTRAINT_PRIMARY) ",");
+		if (showTrigger)
+			appendPQExpBufferStr(&buf, CppAsString2(CONSTRAINT_TRIGGER) ",");
+		if (showUnique)
+			appendPQExpBufferStr(&buf, CppAsString2(CONSTRAINT_UNIQUE) ",");
+		if (showExclusion)
+			appendPQExpBufferStr(&buf, CppAsString2(CONSTRAINT_EXCLUSION) ",");
+
+		appendPQExpBufferStr(&buf, "''");	/* dummy */
+		appendPQExpBufferStr(&buf, ")\n");
+	}
+
+	appendPQExpBufferStr(&buf, "ORDER BY 1, 2;");
+
+	res = PSQLexec(buf.data);
+	termPQExpBuffer(&buf);
+	if (!res)
+		return false;
+
+	myopt.nullPrint = NULL;
+	myopt.title = _("List of constraints");
+	myopt.translate_header = true;
+
+	printQuery(res, &myopt, pset.queryFout, false, pset.logfile);
+
+	PQclear(res);
+	return true;
+}
+
+/*
  * \dC
  *
  * Describes casts.
diff --git a/src/bin/psql/describe.h b/src/bin/psql/describe.h
index fd60796..0929ff5 100644
--- a/src/bin/psql/describe.h
+++ b/src/bin/psql/describe.h
@@ -76,6 +76,9 @@ extern bool listDomains(const char *pattern, bool verbose, bool showSystem);
 /* \dc */
 extern bool listConversions(const char *pattern, bool verbose, bool showSystem);
 
+/* \dco */
+extern bool listConstraints(const char *contypes, const char *pattern, bool verbose, bool showSystem);
+
 /* \dC */
 extern bool listCasts(const char *pattern, bool verbose);
 
diff --git a/src/bin/psql/help.c b/src/bin/psql/help.c
index 56afa68..6cfee66 100644
--- a/src/bin/psql/help.c
+++ b/src/bin/psql/help.c
@@ -231,6 +231,7 @@ slashUsage(unsigned short int pager)
 	fprintf(output, _("  \\dAp[+] [AMPTRN [OPFPTRN]]   list support functions of operator families\n"));
 	fprintf(output, _("  \\db[+]  [PATTERN]      list tablespaces\n"));
 	fprintf(output, _("  \\dc[S+] [PATTERN]      list conversions\n"));
+	fprintf(output, _("  \\dco[cfptuxS+] [PATTERN] list constraints\n"));
 	fprintf(output, _("  \\dC[+]  [PATTERN]      list casts\n"));
 	fprintf(output, _("  \\dd[S]  [PATTERN]      show object descriptions not displayed elsewhere\n"));
 	fprintf(output, _("  \\dD[S+] [PATTERN]      list domains\n"));