chained transactions

From e964e279827635feb95df7d6518a6ba9fa55a4df Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter_e@gmx.net>
Date: Fri, 16 Feb 2018 21:37:55 -0500
Subject: [PATCH v2 1/2] Transaction chaining

Add command variants COMMIT AND CHAIN and ROLLBACK AND CHAIN, which
start new transactions with the same transaction characteristics as the
just finished one, per SQL standard.
---
 doc/src/sgml/ref/abort.sgml                |  14 ++-
 doc/src/sgml/ref/commit.sgml               |  14 ++-
 doc/src/sgml/ref/end.sgml                  |  14 ++-
 doc/src/sgml/ref/rollback.sgml             |  14 ++-
 src/backend/access/transam/xact.c          |  73 ++++++++++-
 src/backend/catalog/sql_features.txt       |   2 +-
 src/backend/nodes/copyfuncs.c              |   1 +
 src/backend/nodes/equalfuncs.c             |   1 +
 src/backend/parser/gram.y                  |  19 ++-
 src/backend/tcop/utility.c                 |   4 +-
 src/include/access/xact.h                  |   4 +-
 src/include/nodes/parsenodes.h             |   1 +
 src/test/regress/expected/transactions.out | 139 +++++++++++++++++++++
 src/test/regress/sql/transactions.sql      |  49 ++++++++
 14 files changed, 333 insertions(+), 16 deletions(-)

diff --git a/doc/src/sgml/ref/abort.sgml b/doc/src/sgml/ref/abort.sgml
index 21799d2a83..0372913365 100644
--- a/doc/src/sgml/ref/abort.sgml
+++ b/doc/src/sgml/ref/abort.sgml
@@ -21,7 +21,7 @@
 
  <refsynopsisdiv>
 <synopsis>
-ABORT [ WORK | TRANSACTION ]
+ABORT [ WORK | TRANSACTION ] [ AND [ NO ] CHAIN ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -51,6 +51,18 @@ <title>Parameters</title>
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term><literal>AND CHAIN</literal></term>
+    <listitem>
+     <para>
+      If <literal>AND CHAIN</literal> is specified, a new transaction is
+      immediately started with the same transaction characteristics (see <xref
+      linkend="sql-set-transaction"/>) as the just finished one.  Otherwise,
+      no new transaction is started.
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
  </refsect1>
 
diff --git a/doc/src/sgml/ref/commit.sgml b/doc/src/sgml/ref/commit.sgml
index b2e8d5d180..37c706a66f 100644
--- a/doc/src/sgml/ref/commit.sgml
+++ b/doc/src/sgml/ref/commit.sgml
@@ -21,7 +21,7 @@
 
  <refsynopsisdiv>
 <synopsis>
-COMMIT [ WORK | TRANSACTION ]
+COMMIT [ WORK | TRANSACTION ] [ AND [ NO ] CHAIN ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -48,6 +48,18 @@ <title>Parameters</title>
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term><literal>AND CHAIN</literal></term>
+    <listitem>
+     <para>
+      If <literal>AND CHAIN</literal> is specified, a new transaction is
+      immediately started with the same transaction characteristics (see <xref
+      linkend="sql-set-transaction"/>) as the just finished one.  Otherwise,
+      no new transaction is started.
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
  </refsect1>
 
diff --git a/doc/src/sgml/ref/end.sgml b/doc/src/sgml/ref/end.sgml
index 7523315f34..8b8f4f0dbb 100644
--- a/doc/src/sgml/ref/end.sgml
+++ b/doc/src/sgml/ref/end.sgml
@@ -21,7 +21,7 @@
 
  <refsynopsisdiv>
 <synopsis>
-END [ WORK | TRANSACTION ]
+END [ WORK | TRANSACTION ] [ AND [ NO ] CHAIN ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -50,6 +50,18 @@ <title>Parameters</title>
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term><literal>AND CHAIN</literal></term>
+    <listitem>
+     <para>
+      If <literal>AND CHAIN</literal> is specified, a new transaction is
+      immediately started with the same transaction characteristics (see <xref
+      linkend="sql-set-transaction"/>) as the just finished one.  Otherwise,
+      no new transaction is started.
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
  </refsect1>
 
diff --git a/doc/src/sgml/ref/rollback.sgml b/doc/src/sgml/ref/rollback.sgml
index 3cafb848a9..3019273a47 100644
--- a/doc/src/sgml/ref/rollback.sgml
+++ b/doc/src/sgml/ref/rollback.sgml
@@ -21,7 +21,7 @@
 
  <refsynopsisdiv>
 <synopsis>
-ROLLBACK [ WORK | TRANSACTION ]
+ROLLBACK [ WORK | TRANSACTION ] [ AND [ NO ] CHAIN ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -47,6 +47,18 @@ <title>Parameters</title>
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term><literal>AND CHAIN</literal></term>
+    <listitem>
+     <para>
+      If <literal>AND CHAIN</literal> is specified, a new transaction is
+      immediately started with the same transaction characteristics (see <xref
+      linkend="sql-set-transaction"/>) as the just finished one.  Otherwise,
+      no new transaction is started.
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
  </refsect1>
 
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index e3f668bf6a..58565f1f72 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -188,6 +188,7 @@ typedef struct TransactionStateData
 	bool		startedInRecovery;	/* did we start in recovery? */
 	bool		didLogXid;		/* has xid been included in WAL record? */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
+	bool		chain;			/* start a new block after this one */
 	struct TransactionStateData *parent;	/* back link to parent */
 } TransactionStateData;
 
@@ -2746,6 +2747,36 @@ StartTransactionCommand(void)
 	MemoryContextSwitchTo(CurTransactionContext);
 }
 
+
+/*
+ * Simple system for saving and restoring transaction characteristics
+ * (isolation level, read only, deferrable).  We need this for transaction
+ * chaining, so that we can set the characteristics of the new transaction to
+ * be the same as the previous one.  (We need something like this because the
+ * GUC system resets the characteristics at transaction end, so for example
+ * just skipping the reset in StartTransaction() won't work.)
+ */
+static int	save_XactIsoLevel;
+static bool	save_XactReadOnly;
+static bool	save_XactDeferrable;
+
+static void
+SaveTransactionCharacteristics(void)
+{
+	save_XactIsoLevel = XactIsoLevel;
+	save_XactReadOnly = XactReadOnly;
+	save_XactDeferrable = XactDeferrable;
+}
+
+static void
+RestoreTransactionCharacteristics(void)
+{
+	XactIsoLevel = save_XactIsoLevel;
+	XactReadOnly = save_XactReadOnly;
+	XactDeferrable = save_XactDeferrable;
+}
+
+
 /*
  *	CommitTransactionCommand
  */
@@ -2754,6 +2785,9 @@ CommitTransactionCommand(void)
 {
 	TransactionState s = CurrentTransactionState;
 
+	if (s->chain)
+		SaveTransactionCharacteristics();
+
 	switch (s->blockState)
 	{
 			/*
@@ -2805,6 +2839,13 @@ CommitTransactionCommand(void)
 		case TBLOCK_END:
 			CommitTransaction();
 			s->blockState = TBLOCK_DEFAULT;
+			if (s->chain)
+			{
+				StartTransaction();
+				s->blockState = TBLOCK_INPROGRESS;
+				s->chain = false;
+				RestoreTransactionCharacteristics();
+			}
 			break;
 
 			/*
@@ -2824,6 +2865,13 @@ CommitTransactionCommand(void)
 		case TBLOCK_ABORT_END:
 			CleanupTransaction();
 			s->blockState = TBLOCK_DEFAULT;
+			if (s->chain)
+			{
+				StartTransaction();
+				s->blockState = TBLOCK_INPROGRESS;
+				s->chain = false;
+				RestoreTransactionCharacteristics();
+			}
 			break;
 
 			/*
@@ -2835,6 +2883,13 @@ CommitTransactionCommand(void)
 			AbortTransaction();
 			CleanupTransaction();
 			s->blockState = TBLOCK_DEFAULT;
+			if (s->chain)
+			{
+				StartTransaction();
+				s->blockState = TBLOCK_INPROGRESS;
+				s->chain = false;
+				RestoreTransactionCharacteristics();
+			}
 			break;
 
 			/*
@@ -3492,7 +3547,7 @@ PrepareTransactionBlock(const char *gid)
 	bool		result;
 
 	/* Set up to commit the current transaction */
-	result = EndTransactionBlock();
+	result = EndTransactionBlock(false);
 
 	/* If successful, change outer tblock state to PREPARE */
 	if (result)
@@ -3538,7 +3593,7 @@ PrepareTransactionBlock(const char *gid)
  * resource owner, etc while executing inside a Portal.
  */
 bool
-EndTransactionBlock(void)
+EndTransactionBlock(bool chain)
 {
 	TransactionState s = CurrentTransactionState;
 	bool		result = false;
@@ -3664,6 +3719,13 @@ EndTransactionBlock(void)
 			break;
 	}
 
+	Assert(s->blockState == TBLOCK_STARTED ||
+		   s->blockState == TBLOCK_END ||
+		   s->blockState == TBLOCK_ABORT_END ||
+		   s->blockState == TBLOCK_ABORT_PENDING);
+
+	s->chain = chain;
+
 	return result;
 }
 
@@ -3674,7 +3736,7 @@ EndTransactionBlock(void)
  * As above, we don't actually do anything here except change blockState.
  */
 void
-UserAbortTransactionBlock(void)
+UserAbortTransactionBlock(bool chain)
 {
 	TransactionState s = CurrentTransactionState;
 
@@ -3772,6 +3834,11 @@ UserAbortTransactionBlock(void)
 				 BlockStateAsString(s->blockState));
 			break;
 	}
+
+	Assert(s->blockState == TBLOCK_ABORT_END ||
+		   s->blockState == TBLOCK_ABORT_PENDING);
+
+	s->chain = chain;
 }
 
 /*
diff --git a/src/backend/catalog/sql_features.txt b/src/backend/catalog/sql_features.txt
index aeb262a5b0..49df7e08c0 100644
--- a/src/backend/catalog/sql_features.txt
+++ b/src/backend/catalog/sql_features.txt
@@ -443,7 +443,7 @@ T213	INSTEAD OF triggers			YES
 T231	Sensitive cursors			YES	
 T241	START TRANSACTION statement			YES	
 T251	SET TRANSACTION statement: LOCAL option			NO	
-T261	Chained transactions			NO	
+T261	Chained transactions			YES	
 T271	Savepoints			YES	
 T272	Enhanced savepoint management			NO	
 T281	SELECT privilege with column granularity			YES	
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index e47641d572..f78aa375fc 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -3655,6 +3655,7 @@ _copyTransactionStmt(const TransactionStmt *from)
 	COPY_NODE_FIELD(options);
 	COPY_STRING_FIELD(savepoint_name);
 	COPY_STRING_FIELD(gid);
+	COPY_SCALAR_FIELD(chain);
 
 	return newnode;
 }
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 3bb91c9595..8c6162c67d 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -1506,6 +1506,7 @@ _equalTransactionStmt(const TransactionStmt *a, const TransactionStmt *b)
 	COMPARE_NODE_FIELD(options);
 	COMPARE_STRING_FIELD(savepoint_name);
 	COMPARE_STRING_FIELD(gid);
+	COMPARE_SCALAR_FIELD(chain);
 
 	return true;
 }
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 6d23bfb0b3..bc42b3400f 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -310,6 +310,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 %type <boolean>	opt_or_replace
 				opt_grant_grant_option opt_grant_admin_option
 				opt_nowait opt_if_exists opt_with_data
+				opt_transaction_chain
 %type <ival>	opt_nowait_or_skip
 
 %type <list>	OptRoleList AlterOptRoleList
@@ -9832,11 +9833,12 @@ UnlistenStmt:
  *****************************************************************************/
 
 TransactionStmt:
-			ABORT_P opt_transaction
+			ABORT_P opt_transaction opt_transaction_chain
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
 					n->kind = TRANS_STMT_ROLLBACK;
 					n->options = NIL;
+					n->chain = $3;
 					$$ = (Node *)n;
 				}
 			| BEGIN_P opt_transaction transaction_mode_list_or_empty
@@ -9853,25 +9855,28 @@ TransactionStmt:
 					n->options = $3;
 					$$ = (Node *)n;
 				}
-			| COMMIT opt_transaction
+			| COMMIT opt_transaction opt_transaction_chain
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
 					n->kind = TRANS_STMT_COMMIT;
 					n->options = NIL;
+					n->chain = $3;
 					$$ = (Node *)n;
 				}
-			| END_P opt_transaction
+			| END_P opt_transaction opt_transaction_chain
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
 					n->kind = TRANS_STMT_COMMIT;
 					n->options = NIL;
+					n->chain = $3;
 					$$ = (Node *)n;
 				}
-			| ROLLBACK opt_transaction
+			| ROLLBACK opt_transaction opt_transaction_chain
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
 					n->kind = TRANS_STMT_ROLLBACK;
 					n->options = NIL;
+					n->chain = $3;
 					$$ = (Node *)n;
 				}
 			| SAVEPOINT ColId
@@ -9971,6 +9976,12 @@ transaction_mode_list_or_empty:
 					{ $$ = NIL; }
 		;
 
+opt_transaction_chain:
+			AND CHAIN		{ $$ = true; }
+			| AND NO CHAIN	{ $$ = false; }
+			| /* EMPTY */	{ $$ = false; }
+		;
+
 
 /*****************************************************************************
  *
diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c
index b5804f64ad..4c3ac2689b 100644
--- a/src/backend/tcop/utility.c
+++ b/src/backend/tcop/utility.c
@@ -437,7 +437,7 @@ standard_ProcessUtility(PlannedStmt *pstmt,
 						break;
 
 					case TRANS_STMT_COMMIT:
-						if (!EndTransactionBlock())
+						if (!EndTransactionBlock(stmt->chain))
 						{
 							/* report unsuccessful commit in completionTag */
 							if (completionTag)
@@ -468,7 +468,7 @@ standard_ProcessUtility(PlannedStmt *pstmt,
 						break;
 
 					case TRANS_STMT_ROLLBACK:
-						UserAbortTransactionBlock();
+						UserAbortTransactionBlock(stmt->chain);
 						break;
 
 					case TRANS_STMT_SAVEPOINT:
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 689c57c592..c757146e4d 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -372,9 +372,9 @@ extern void StartTransactionCommand(void);
 extern void CommitTransactionCommand(void);
 extern void AbortCurrentTransaction(void);
 extern void BeginTransactionBlock(void);
-extern bool EndTransactionBlock(void);
+extern bool EndTransactionBlock(bool chain);
 extern bool PrepareTransactionBlock(const char *gid);
-extern void UserAbortTransactionBlock(void);
+extern void UserAbortTransactionBlock(bool chain);
 extern void BeginImplicitTransactionBlock(void);
 extern void EndImplicitTransactionBlock(void);
 extern void ReleaseSavepoint(const char *name);
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index aa4a0dba2a..da34aeb27f 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2989,6 +2989,7 @@ typedef struct TransactionStmt
 	List	   *options;		/* for BEGIN/START commands */
 	char	   *savepoint_name; /* for savepoint commands */
 	char	   *gid;			/* for two-phase-commit related commands */
+	bool		chain;			/* AND CHAIN option */
 } TransactionStmt;
 
 /* ----------------------
diff --git a/src/test/regress/expected/transactions.out b/src/test/regress/expected/transactions.out
index 69e176c525..0167520333 100644
--- a/src/test/regress/expected/transactions.out
+++ b/src/test/regress/expected/transactions.out
@@ -659,6 +659,145 @@ ERROR:  portal "ctt" cannot be run
 COMMIT;
 DROP FUNCTION create_temp_tab();
 DROP FUNCTION invert(x float8);
+-- Tests for AND CHAIN
+CREATE TABLE abc (a int);
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ, DEFERRABLE;
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ on
+(1 row)
+
+INSERT INTO abc VALUES (1);
+INSERT INTO abc VALUES (2);
+COMMIT AND CHAIN;  -- TBLOCK_END
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ on
+(1 row)
+
+INSERT INTO abc VALUES ('error');
+ERROR:  invalid input syntax for type integer: "error"
+LINE 1: INSERT INTO abc VALUES ('error');
+                                ^
+INSERT INTO abc VALUES (3);  -- check it's really aborted
+ERROR:  current transaction is aborted, commands ignored until end of transaction block
+COMMIT AND CHAIN;  -- TBLOCK_ABORT_END
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ on
+(1 row)
+
+INSERT INTO abc VALUES (3);
+COMMIT;
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ, DEFERRABLE;
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ on
+(1 row)
+
+SAVEPOINT x;
+INSERT INTO abc VALUES ('error');
+ERROR:  invalid input syntax for type integer: "error"
+LINE 1: INSERT INTO abc VALUES ('error');
+                                ^
+COMMIT AND CHAIN;  -- TBLOCK_ABORT_PENDING
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ on
+(1 row)
+
+INSERT INTO abc VALUES (4);
+COMMIT;
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ, DEFERRABLE;
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ on
+(1 row)
+
+INSERT INTO abc VALUES (5);
+ROLLBACK AND CHAIN;  -- TBLOCK_ABORT_PENDING
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ on
+(1 row)
+
+INSERT INTO abc VALUES ('error');
+ERROR:  invalid input syntax for type integer: "error"
+LINE 1: INSERT INTO abc VALUES ('error');
+                                ^
+ROLLBACK AND CHAIN;  -- TBLOCK_ABORT_END
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ on
+(1 row)
+
+ROLLBACK;
+SELECT * FROM abc ORDER BY 1;
+ a 
+---
+ 1
+ 2
+ 3
+ 4
+(4 rows)
+
+DROP TABLE abc;
 -- Test assorted behaviors around the implicit transaction block created
 -- when multiple SQL commands are sent in a single Query message.  These
 -- tests rely on the fact that psql will not break SQL commands apart at a
diff --git a/src/test/regress/sql/transactions.sql b/src/test/regress/sql/transactions.sql
index 2e3739fd6c..7cd89f2477 100644
--- a/src/test/regress/sql/transactions.sql
+++ b/src/test/regress/sql/transactions.sql
@@ -419,6 +419,55 @@ CREATE FUNCTION create_temp_tab() RETURNS text
 DROP FUNCTION invert(x float8);
 
 
+-- Tests for AND CHAIN
+
+CREATE TABLE abc (a int);
+
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ, DEFERRABLE;
+SHOW transaction_isolation;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES (1);
+INSERT INTO abc VALUES (2);
+COMMIT AND CHAIN;  -- TBLOCK_END
+SHOW transaction_isolation;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES ('error');
+INSERT INTO abc VALUES (3);  -- check it's really aborted
+COMMIT AND CHAIN;  -- TBLOCK_ABORT_END
+SHOW transaction_isolation;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES (3);
+COMMIT;
+
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ, DEFERRABLE;
+SHOW transaction_isolation;
+SHOW transaction_deferrable;
+SAVEPOINT x;
+INSERT INTO abc VALUES ('error');
+COMMIT AND CHAIN;  -- TBLOCK_ABORT_PENDING
+SHOW transaction_isolation;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES (4);
+COMMIT;
+
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ, DEFERRABLE;
+SHOW transaction_isolation;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES (5);
+ROLLBACK AND CHAIN;  -- TBLOCK_ABORT_PENDING
+SHOW transaction_isolation;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES ('error');
+ROLLBACK AND CHAIN;  -- TBLOCK_ABORT_END
+SHOW transaction_isolation;
+SHOW transaction_deferrable;
+ROLLBACK;
+
+SELECT * FROM abc ORDER BY 1;
+
+DROP TABLE abc;
+
+
 -- Test assorted behaviors around the implicit transaction block created
 -- when multiple SQL commands are sent in a single Query message.  These
 -- tests rely on the fact that psql will not break SQL commands apart at a

base-commit: eee01d606eb40f760799320e75d45c84022353d8
-- 
2.19.0

From 647de712265239fa03cab409bb239a226204dc20 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter_e@gmx.net>
Date: Wed, 28 Feb 2018 10:04:06 -0500
Subject: [PATCH v2 2/2] Transaction chaining support in PL/pgSQL

---
 doc/src/sgml/plpgsql.sgml                     |  9 ++++++
 doc/src/sgml/spi.sgml                         | 14 ++++++---
 src/backend/access/transam/xact.c             |  4 +--
 src/backend/executor/spi.c                    | 24 ++++++++++++--
 src/include/access/xact.h                     |  2 ++
 src/include/executor/spi.h                    |  4 +--
 src/pl/plperl/plperl.c                        |  4 +--
 .../src/expected/plpgsql_transaction.out      | 31 +++++++++++++++++++
 src/pl/plpgsql/src/pl_exec.c                  | 10 +++---
 src/pl/plpgsql/src/pl_funcs.c                 | 10 ++++--
 src/pl/plpgsql/src/pl_gram.y                  | 18 +++++++++--
 src/pl/plpgsql/src/pl_scanner.c               |  2 ++
 src/pl/plpgsql/src/plpgsql.h                  |  2 ++
 .../plpgsql/src/sql/plpgsql_transaction.sql   | 23 ++++++++++++++
 src/pl/plpython/plpy_plpymodule.c             |  4 +--
 src/pl/tcl/pltcl.c                            |  4 +--
 16 files changed, 141 insertions(+), 24 deletions(-)

diff --git a/doc/src/sgml/plpgsql.sgml b/doc/src/sgml/plpgsql.sgml
index 4344ceadbe..321953fd46 100644
--- a/doc/src/sgml/plpgsql.sgml
+++ b/doc/src/sgml/plpgsql.sgml
@@ -3478,6 +3478,15 @@ <title>Transaction Management</title>
 </programlisting>
    </para>
 
+   <para>
+    A new transaction starts out with default transaction characteristics such
+    as transaction isolation level.  In cases where transactions are committed
+    in a loop, it might be desirable to start new transactions automatically
+    with the same characteristics as the previous one.  The commands
+    <command>COMMIT AND CHAIN</command> and <command>ROLLBACK AND
+    CHAIN</command> accomplish this.
+   </para>
+
    <para>
     Transaction control is only possible in <command>CALL</command> or
     <command>DO</command> invocations from the top level or nested
diff --git a/doc/src/sgml/spi.sgml b/doc/src/sgml/spi.sgml
index 9db11d22fb..9b4e63e352 100644
--- a/doc/src/sgml/spi.sgml
+++ b/doc/src/sgml/spi.sgml
@@ -4389,7 +4389,7 @@ <title>Transaction Management</title>
 
  <refsynopsisdiv>
 <synopsis>
-void SPI_commit(void)
+void SPI_commit(bool <parameter>chain</parameter>)
 </synopsis>
  </refsynopsisdiv>
 
@@ -4402,7 +4402,10 @@ <title>Description</title>
    command <command>COMMIT</command>.  After a transaction is committed, a new
    transaction has to be started
    using <function>SPI_start_transaction</function> before further database
-   actions can be executed.
+   actions can be executed.  If <parameter>chain</parameter> is true, then a
+   new transaction is immediately started with the same transaction
+   characteristics as the just finished one, like with the SQL command
+   <command>COMMIT AND CHAIN</command>.
   </para>
 
   <para>
@@ -4429,7 +4432,7 @@ <title>Description</title>
 
  <refsynopsisdiv>
 <synopsis>
-void SPI_rollback(void)
+void SPI_rollback(bool <parameter>chain</parameter>)
 </synopsis>
  </refsynopsisdiv>
 
@@ -4442,7 +4445,10 @@ <title>Description</title>
    command <command>ROLLBACK</command>.  After a transaction is rolled back, a
    new transaction has to be started
    using <function>SPI_start_transaction</function> before further database
-   actions can be executed.
+   actions can be executed.  If <parameter>chain</parameter> is true, then a
+   new transaction is immediately started with the same transaction
+   characteristics as the just finished one, like with the SQL command
+   <command>COMMIT AND CHAIN</command>.
   </para>
 
   <para>
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 58565f1f72..b4aa8ab6e0 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -2760,7 +2760,7 @@ static int	save_XactIsoLevel;
 static bool	save_XactReadOnly;
 static bool	save_XactDeferrable;
 
-static void
+void
 SaveTransactionCharacteristics(void)
 {
 	save_XactIsoLevel = XactIsoLevel;
@@ -2768,7 +2768,7 @@ SaveTransactionCharacteristics(void)
 	save_XactDeferrable = XactDeferrable;
 }
 
-static void
+void
 RestoreTransactionCharacteristics(void)
 {
 	XactIsoLevel = save_XactIsoLevel;
diff --git a/src/backend/executor/spi.c b/src/backend/executor/spi.c
index 11ca800e4c..444a8765f7 100644
--- a/src/backend/executor/spi.c
+++ b/src/backend/executor/spi.c
@@ -223,7 +223,7 @@ SPI_start_transaction(void)
 }
 
 void
-SPI_commit(void)
+SPI_commit(bool chain)
 {
 	MemoryContext oldcontext = CurrentMemoryContext;
 
@@ -255,14 +255,24 @@ SPI_commit(void)
 	while (ActiveSnapshotSet())
 		PopActiveSnapshot();
 
+	if (chain)
+		SaveTransactionCharacteristics();
+
 	CommitTransactionCommand();
+
+	if (chain)
+	{
+		StartTransactionCommand();
+		RestoreTransactionCharacteristics();
+	}
+
 	MemoryContextSwitchTo(oldcontext);
 
 	_SPI_current->internal_xact = false;
 }
 
 void
-SPI_rollback(void)
+SPI_rollback(bool chain)
 {
 	MemoryContext oldcontext = CurrentMemoryContext;
 
@@ -279,7 +289,17 @@ SPI_rollback(void)
 
 	_SPI_current->internal_xact = true;
 
+	if (chain)
+		SaveTransactionCharacteristics();
+
 	AbortCurrentTransaction();
+
+	if (chain)
+	{
+		StartTransactionCommand();
+		RestoreTransactionCharacteristics();
+	}
+
 	MemoryContextSwitchTo(oldcontext);
 
 	_SPI_current->internal_xact = false;
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index c757146e4d..2abdbece6c 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -369,6 +369,8 @@ extern bool TransactionIdIsCurrentTransactionId(TransactionId xid);
 extern void CommandCounterIncrement(void);
 extern void ForceSyncCommit(void);
 extern void StartTransactionCommand(void);
+extern void SaveTransactionCharacteristics(void);
+extern void RestoreTransactionCharacteristics(void);
 extern void CommitTransactionCommand(void);
 extern void AbortCurrentTransaction(void);
 extern void BeginTransactionBlock(void);
diff --git a/src/include/executor/spi.h b/src/include/executor/spi.h
index 143a89a16c..a391e92405 100644
--- a/src/include/executor/spi.h
+++ b/src/include/executor/spi.h
@@ -160,8 +160,8 @@ extern int	SPI_unregister_relation(const char *name);
 extern int	SPI_register_trigger_data(TriggerData *tdata);
 
 extern void SPI_start_transaction(void);
-extern void SPI_commit(void);
-extern void SPI_rollback(void);
+extern void SPI_commit(bool chain);
+extern void SPI_rollback(bool chain);
 
 extern void SPICleanup(void);
 extern void AtEOXact_SPI(bool isCommit);
diff --git a/src/pl/plperl/plperl.c b/src/pl/plperl/plperl.c
index 4cfc506253..003fd594c6 100644
--- a/src/pl/plperl/plperl.c
+++ b/src/pl/plperl/plperl.c
@@ -3968,7 +3968,7 @@ plperl_spi_commit(void)
 	{
 		HoldPinnedPortals();
 
-		SPI_commit();
+		SPI_commit(false);
 		SPI_start_transaction();
 	}
 	PG_CATCH();
@@ -3995,7 +3995,7 @@ plperl_spi_rollback(void)
 	{
 		HoldPinnedPortals();
 
-		SPI_rollback();
+		SPI_rollback(false);
 		SPI_start_transaction();
 	}
 	PG_CATCH();
diff --git a/src/pl/plpgsql/src/expected/plpgsql_transaction.out b/src/pl/plpgsql/src/expected/plpgsql_transaction.out
index 77a83adab5..5441e997a6 100644
--- a/src/pl/plpgsql/src/expected/plpgsql_transaction.out
+++ b/src/pl/plpgsql/src/expected/plpgsql_transaction.out
@@ -493,6 +493,37 @@ CALL transaction_test10b(10);
  9
 (1 row)
 
+-- transaction chain
+TRUNCATE test1;
+DO LANGUAGE plpgsql $$
+BEGIN
+    ROLLBACK;
+    SET TRANSACTION ISOLATION LEVEL REPEATABLE READ;
+    FOR i IN 0..5 LOOP
+        RAISE INFO 'transaction_isolation = %', current_setting('transaction_isolation');
+        INSERT INTO test1 (a) VALUES (i);
+        IF i % 2 = 0 THEN
+            COMMIT AND CHAIN;
+        ELSE
+            ROLLBACK AND CHAIN;
+        END IF;
+    END LOOP;
+END
+$$;
+INFO:  transaction_isolation = repeatable read
+INFO:  transaction_isolation = repeatable read
+INFO:  transaction_isolation = repeatable read
+INFO:  transaction_isolation = repeatable read
+INFO:  transaction_isolation = repeatable read
+INFO:  transaction_isolation = repeatable read
+SELECT * FROM test1;
+ a | b 
+---+---
+ 0 | 
+ 2 | 
+ 4 | 
+(3 rows)
+
 DROP TABLE test1;
 DROP TABLE test2;
 DROP TABLE test3;
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index 45526383f2..68567afb03 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -4753,8 +4753,9 @@ exec_stmt_commit(PLpgSQL_execstate *estate, PLpgSQL_stmt_commit *stmt)
 {
 	HoldPinnedPortals();
 
-	SPI_commit();
-	SPI_start_transaction();
+	SPI_commit(stmt->chain);
+	if (!stmt->chain)
+		SPI_start_transaction();
 
 	estate->simple_eval_estate = NULL;
 	plpgsql_create_econtext(estate);
@@ -4772,8 +4773,9 @@ exec_stmt_rollback(PLpgSQL_execstate *estate, PLpgSQL_stmt_rollback *stmt)
 {
 	HoldPinnedPortals();
 
-	SPI_rollback();
-	SPI_start_transaction();
+	SPI_rollback(stmt->chain);
+	if (!stmt->chain)
+		SPI_start_transaction();
 
 	estate->simple_eval_estate = NULL;
 	plpgsql_create_econtext(estate);
diff --git a/src/pl/plpgsql/src/pl_funcs.c b/src/pl/plpgsql/src/pl_funcs.c
index b93f866223..a2e9a8dcb8 100644
--- a/src/pl/plpgsql/src/pl_funcs.c
+++ b/src/pl/plpgsql/src/pl_funcs.c
@@ -1320,14 +1320,20 @@ static void
 dump_commit(PLpgSQL_stmt_commit *stmt)
 {
 	dump_ind();
-	printf("COMMIT\n");
+	if (stmt->chain)
+		printf("COMMIT AND CHAIN\n");
+	else
+		printf("COMMIT\n");
 }
 
 static void
 dump_rollback(PLpgSQL_stmt_rollback *stmt)
 {
 	dump_ind();
-	printf("ROLLBACK\n");
+	if (stmt->chain)
+		printf("ROLLBACK AND CHAIN\n");
+	else
+		printf("ROLLBACK\n");
 }
 
 static void
diff --git a/src/pl/plpgsql/src/pl_gram.y b/src/pl/plpgsql/src/pl_gram.y
index 68e399f9cf..498c17c0fb 100644
--- a/src/pl/plpgsql/src/pl_gram.y
+++ b/src/pl/plpgsql/src/pl_gram.y
@@ -219,6 +219,8 @@ static	void			check_raise_parameters(PLpgSQL_stmt_raise *stmt);
 %type <ival>	opt_scrollable
 %type <fetch>	opt_fetch_direction
 
+%type <ival>	opt_transaction_chain
+
 %type <keyword>	unreserved_keyword
 
 
@@ -252,6 +254,7 @@ static	void			check_raise_parameters(PLpgSQL_stmt_raise *stmt);
 %token <keyword>	K_ABSOLUTE
 %token <keyword>	K_ALIAS
 %token <keyword>	K_ALL
+%token <keyword>	K_AND
 %token <keyword>	K_ARRAY
 %token <keyword>	K_ASSERT
 %token <keyword>	K_BACKWARD
@@ -259,6 +262,7 @@ static	void			check_raise_parameters(PLpgSQL_stmt_raise *stmt);
 %token <keyword>	K_BY
 %token <keyword>	K_CALL
 %token <keyword>	K_CASE
+%token <keyword>	K_CHAIN
 %token <keyword>	K_CLOSE
 %token <keyword>	K_COLLATE
 %token <keyword>	K_COLUMN
@@ -2182,30 +2186,38 @@ stmt_null		: K_NULL ';'
 					}
 				;
 
-stmt_commit		: K_COMMIT ';'
+stmt_commit		: K_COMMIT opt_transaction_chain ';'
 					{
 						PLpgSQL_stmt_commit *new;
 
 						new = palloc(sizeof(PLpgSQL_stmt_commit));
 						new->cmd_type = PLPGSQL_STMT_COMMIT;
 						new->lineno = plpgsql_location_to_lineno(@1);
+						new->chain = $2;
 
 						$$ = (PLpgSQL_stmt *)new;
 					}
 				;
 
-stmt_rollback	: K_ROLLBACK ';'
+stmt_rollback	: K_ROLLBACK opt_transaction_chain ';'
 					{
 						PLpgSQL_stmt_rollback *new;
 
 						new = palloc(sizeof(PLpgSQL_stmt_rollback));
 						new->cmd_type = PLPGSQL_STMT_ROLLBACK;
 						new->lineno = plpgsql_location_to_lineno(@1);
+						new->chain = $2;
 
 						$$ = (PLpgSQL_stmt *)new;
 					}
 				;
 
+opt_transaction_chain:
+			K_AND K_CHAIN			{ $$ = true; }
+			| K_AND K_NO K_CHAIN	{ $$ = false; }
+			| /* EMPTY */			{ $$ = false; }
+				;
+
 stmt_set	: K_SET
 					{
 						PLpgSQL_stmt_set *new;
@@ -2460,10 +2472,12 @@ any_identifier	: T_WORD
 unreserved_keyword	:
 				K_ABSOLUTE
 				| K_ALIAS
+				| K_AND
 				| K_ARRAY
 				| K_ASSERT
 				| K_BACKWARD
 				| K_CALL
+				| K_CHAIN
 				| K_CLOSE
 				| K_COLLATE
 				| K_COLUMN
diff --git a/src/pl/plpgsql/src/pl_scanner.c b/src/pl/plpgsql/src/pl_scanner.c
index fc4ba3054a..0be191f270 100644
--- a/src/pl/plpgsql/src/pl_scanner.c
+++ b/src/pl/plpgsql/src/pl_scanner.c
@@ -99,10 +99,12 @@ static const int num_reserved_keywords = lengthof(reserved_keywords);
 static const ScanKeyword unreserved_keywords[] = {
 	PG_KEYWORD("absolute", K_ABSOLUTE, UNRESERVED_KEYWORD)
 	PG_KEYWORD("alias", K_ALIAS, UNRESERVED_KEYWORD)
+	PG_KEYWORD("and", K_AND, UNRESERVED_KEYWORD)
 	PG_KEYWORD("array", K_ARRAY, UNRESERVED_KEYWORD)
 	PG_KEYWORD("assert", K_ASSERT, UNRESERVED_KEYWORD)
 	PG_KEYWORD("backward", K_BACKWARD, UNRESERVED_KEYWORD)
 	PG_KEYWORD("call", K_CALL, UNRESERVED_KEYWORD)
+	PG_KEYWORD("chain", K_CHAIN, UNRESERVED_KEYWORD)
 	PG_KEYWORD("close", K_CLOSE, UNRESERVED_KEYWORD)
 	PG_KEYWORD("collate", K_COLLATE, UNRESERVED_KEYWORD)
 	PG_KEYWORD("column", K_COLUMN, UNRESERVED_KEYWORD)
diff --git a/src/pl/plpgsql/src/plpgsql.h b/src/pl/plpgsql/src/plpgsql.h
index f6c35a5049..fad2ad0d87 100644
--- a/src/pl/plpgsql/src/plpgsql.h
+++ b/src/pl/plpgsql/src/plpgsql.h
@@ -534,6 +534,7 @@ typedef struct PLpgSQL_stmt_commit
 {
 	PLpgSQL_stmt_type cmd_type;
 	int			lineno;
+	bool		chain;
 } PLpgSQL_stmt_commit;
 
 /*
@@ -543,6 +544,7 @@ typedef struct PLpgSQL_stmt_rollback
 {
 	PLpgSQL_stmt_type cmd_type;
 	int			lineno;
+	bool		chain;
 } PLpgSQL_stmt_rollback;
 
 /*
diff --git a/src/pl/plpgsql/src/sql/plpgsql_transaction.sql b/src/pl/plpgsql/src/sql/plpgsql_transaction.sql
index 0ed9ab873a..e6a2d89ec7 100644
--- a/src/pl/plpgsql/src/sql/plpgsql_transaction.sql
+++ b/src/pl/plpgsql/src/sql/plpgsql_transaction.sql
@@ -412,6 +412,29 @@ CREATE PROCEDURE transaction_test10b(INOUT x int)
 CALL transaction_test10b(10);
 
 
+-- transaction chain
+
+TRUNCATE test1;
+
+DO LANGUAGE plpgsql $$
+BEGIN
+    ROLLBACK;
+    SET TRANSACTION ISOLATION LEVEL REPEATABLE READ;
+    FOR i IN 0..5 LOOP
+        RAISE INFO 'transaction_isolation = %', current_setting('transaction_isolation');
+        INSERT INTO test1 (a) VALUES (i);
+        IF i % 2 = 0 THEN
+            COMMIT AND CHAIN;
+        ELSE
+            ROLLBACK AND CHAIN;
+        END IF;
+    END LOOP;
+END
+$$;
+
+SELECT * FROM test1;
+
+
 DROP TABLE test1;
 DROP TABLE test2;
 DROP TABLE test3;
diff --git a/src/pl/plpython/plpy_plpymodule.c b/src/pl/plpython/plpy_plpymodule.c
index 23e49e4b75..729f402ea1 100644
--- a/src/pl/plpython/plpy_plpymodule.c
+++ b/src/pl/plpython/plpy_plpymodule.c
@@ -590,7 +590,7 @@ PLy_commit(PyObject *self, PyObject *args)
 
 	HoldPinnedPortals();
 
-	SPI_commit();
+	SPI_commit(false);
 	SPI_start_transaction();
 
 	/* was cleared at transaction end, reset pointer */
@@ -606,7 +606,7 @@ PLy_rollback(PyObject *self, PyObject *args)
 
 	HoldPinnedPortals();
 
-	SPI_rollback();
+	SPI_rollback(false);
 	SPI_start_transaction();
 
 	/* was cleared at transaction end, reset pointer */
diff --git a/src/pl/tcl/pltcl.c b/src/pl/tcl/pltcl.c
index e2fa43b890..7a317e1f89 100644
--- a/src/pl/tcl/pltcl.c
+++ b/src/pl/tcl/pltcl.c
@@ -2957,7 +2957,7 @@ pltcl_commit(ClientData cdata, Tcl_Interp *interp,
 
 	PG_TRY();
 	{
-		SPI_commit();
+		SPI_commit(false);
 		SPI_start_transaction();
 	}
 	PG_CATCH();
@@ -2997,7 +2997,7 @@ pltcl_rollback(ClientData cdata, Tcl_Interp *interp,
 
 	PG_TRY();
 	{
-		SPI_rollback();
+		SPI_rollback(false);
 		SPI_start_transaction();
 	}
 	PG_CATCH();
-- 
2.19.0

From 11488c03bf1c52ce81a659a77aceee88aa1a3f8f Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter_e@gmx.net>
Date: Fri, 16 Feb 2018 21:37:55 -0500
Subject: [PATCH v3 1/2] Transaction chaining

Add command variants COMMIT AND CHAIN and ROLLBACK AND CHAIN, which
start new transactions with the same transaction characteristics as the
just finished one, per SQL standard.
---
 doc/src/sgml/ref/abort.sgml                |  14 +-
 doc/src/sgml/ref/commit.sgml               |  14 +-
 doc/src/sgml/ref/end.sgml                  |  14 +-
 doc/src/sgml/ref/rollback.sgml             |  14 +-
 src/backend/access/transam/xact.c          |  73 +++++++-
 src/backend/catalog/sql_features.txt       |   2 +-
 src/backend/nodes/copyfuncs.c              |   1 +
 src/backend/nodes/equalfuncs.c             |   1 +
 src/backend/parser/gram.y                  |  19 +-
 src/backend/tcop/utility.c                 |   4 +-
 src/bin/psql/tab-complete.c                |   8 +-
 src/include/access/xact.h                  |   4 +-
 src/include/nodes/parsenodes.h             |   1 +
 src/test/regress/expected/transactions.out | 191 +++++++++++++++++++++
 src/test/regress/sql/transactions.sql      |  63 +++++++
 15 files changed, 404 insertions(+), 19 deletions(-)

diff --git a/doc/src/sgml/ref/abort.sgml b/doc/src/sgml/ref/abort.sgml
index 21799d2a83..0372913365 100644
--- a/doc/src/sgml/ref/abort.sgml
+++ b/doc/src/sgml/ref/abort.sgml
@@ -21,7 +21,7 @@
 
  <refsynopsisdiv>
 <synopsis>
-ABORT [ WORK | TRANSACTION ]
+ABORT [ WORK | TRANSACTION ] [ AND [ NO ] CHAIN ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -51,6 +51,18 @@ <title>Parameters</title>
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term><literal>AND CHAIN</literal></term>
+    <listitem>
+     <para>
+      If <literal>AND CHAIN</literal> is specified, a new transaction is
+      immediately started with the same transaction characteristics (see <xref
+      linkend="sql-set-transaction"/>) as the just finished one.  Otherwise,
+      no new transaction is started.
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
  </refsect1>
 
diff --git a/doc/src/sgml/ref/commit.sgml b/doc/src/sgml/ref/commit.sgml
index b2e8d5d180..37c706a66f 100644
--- a/doc/src/sgml/ref/commit.sgml
+++ b/doc/src/sgml/ref/commit.sgml
@@ -21,7 +21,7 @@
 
  <refsynopsisdiv>
 <synopsis>
-COMMIT [ WORK | TRANSACTION ]
+COMMIT [ WORK | TRANSACTION ] [ AND [ NO ] CHAIN ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -48,6 +48,18 @@ <title>Parameters</title>
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term><literal>AND CHAIN</literal></term>
+    <listitem>
+     <para>
+      If <literal>AND CHAIN</literal> is specified, a new transaction is
+      immediately started with the same transaction characteristics (see <xref
+      linkend="sql-set-transaction"/>) as the just finished one.  Otherwise,
+      no new transaction is started.
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
  </refsect1>
 
diff --git a/doc/src/sgml/ref/end.sgml b/doc/src/sgml/ref/end.sgml
index 7523315f34..8b8f4f0dbb 100644
--- a/doc/src/sgml/ref/end.sgml
+++ b/doc/src/sgml/ref/end.sgml
@@ -21,7 +21,7 @@
 
  <refsynopsisdiv>
 <synopsis>
-END [ WORK | TRANSACTION ]
+END [ WORK | TRANSACTION ] [ AND [ NO ] CHAIN ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -50,6 +50,18 @@ <title>Parameters</title>
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term><literal>AND CHAIN</literal></term>
+    <listitem>
+     <para>
+      If <literal>AND CHAIN</literal> is specified, a new transaction is
+      immediately started with the same transaction characteristics (see <xref
+      linkend="sql-set-transaction"/>) as the just finished one.  Otherwise,
+      no new transaction is started.
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
  </refsect1>
 
diff --git a/doc/src/sgml/ref/rollback.sgml b/doc/src/sgml/ref/rollback.sgml
index 3cafb848a9..3019273a47 100644
--- a/doc/src/sgml/ref/rollback.sgml
+++ b/doc/src/sgml/ref/rollback.sgml
@@ -21,7 +21,7 @@
 
  <refsynopsisdiv>
 <synopsis>
-ROLLBACK [ WORK | TRANSACTION ]
+ROLLBACK [ WORK | TRANSACTION ] [ AND [ NO ] CHAIN ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -47,6 +47,18 @@ <title>Parameters</title>
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term><literal>AND CHAIN</literal></term>
+    <listitem>
+     <para>
+      If <literal>AND CHAIN</literal> is specified, a new transaction is
+      immediately started with the same transaction characteristics (see <xref
+      linkend="sql-set-transaction"/>) as the just finished one.  Otherwise,
+      no new transaction is started.
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
  </refsect1>
 
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index d967400384..6af149d788 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -189,6 +189,7 @@ typedef struct TransactionStateData
 	bool		startedInRecovery;	/* did we start in recovery? */
 	bool		didLogXid;		/* has xid been included in WAL record? */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
+	bool		chain;			/* start a new block after this one */
 	struct TransactionStateData *parent;	/* back link to parent */
 } TransactionStateData;
 
@@ -2760,6 +2761,36 @@ StartTransactionCommand(void)
 	MemoryContextSwitchTo(CurTransactionContext);
 }
 
+
+/*
+ * Simple system for saving and restoring transaction characteristics
+ * (isolation level, read only, deferrable).  We need this for transaction
+ * chaining, so that we can set the characteristics of the new transaction to
+ * be the same as the previous one.  (We need something like this because the
+ * GUC system resets the characteristics at transaction end, so for example
+ * just skipping the reset in StartTransaction() won't work.)
+ */
+static int	save_XactIsoLevel;
+static bool	save_XactReadOnly;
+static bool	save_XactDeferrable;
+
+static void
+SaveTransactionCharacteristics(void)
+{
+	save_XactIsoLevel = XactIsoLevel;
+	save_XactReadOnly = XactReadOnly;
+	save_XactDeferrable = XactDeferrable;
+}
+
+static void
+RestoreTransactionCharacteristics(void)
+{
+	XactIsoLevel = save_XactIsoLevel;
+	XactReadOnly = save_XactReadOnly;
+	XactDeferrable = save_XactDeferrable;
+}
+
+
 /*
  *	CommitTransactionCommand
  */
@@ -2768,6 +2799,9 @@ CommitTransactionCommand(void)
 {
 	TransactionState s = CurrentTransactionState;
 
+	if (s->chain)
+		SaveTransactionCharacteristics();
+
 	switch (s->blockState)
 	{
 			/*
@@ -2819,6 +2853,13 @@ CommitTransactionCommand(void)
 		case TBLOCK_END:
 			CommitTransaction();
 			s->blockState = TBLOCK_DEFAULT;
+			if (s->chain)
+			{
+				StartTransaction();
+				s->blockState = TBLOCK_INPROGRESS;
+				s->chain = false;
+				RestoreTransactionCharacteristics();
+			}
 			break;
 
 			/*
@@ -2838,6 +2879,13 @@ CommitTransactionCommand(void)
 		case TBLOCK_ABORT_END:
 			CleanupTransaction();
 			s->blockState = TBLOCK_DEFAULT;
+			if (s->chain)
+			{
+				StartTransaction();
+				s->blockState = TBLOCK_INPROGRESS;
+				s->chain = false;
+				RestoreTransactionCharacteristics();
+			}
 			break;
 
 			/*
@@ -2849,6 +2897,13 @@ CommitTransactionCommand(void)
 			AbortTransaction();
 			CleanupTransaction();
 			s->blockState = TBLOCK_DEFAULT;
+			if (s->chain)
+			{
+				StartTransaction();
+				s->blockState = TBLOCK_INPROGRESS;
+				s->chain = false;
+				RestoreTransactionCharacteristics();
+			}
 			break;
 
 			/*
@@ -3506,7 +3561,7 @@ PrepareTransactionBlock(const char *gid)
 	bool		result;
 
 	/* Set up to commit the current transaction */
-	result = EndTransactionBlock();
+	result = EndTransactionBlock(false);
 
 	/* If successful, change outer tblock state to PREPARE */
 	if (result)
@@ -3552,7 +3607,7 @@ PrepareTransactionBlock(const char *gid)
  * resource owner, etc while executing inside a Portal.
  */
 bool
-EndTransactionBlock(void)
+EndTransactionBlock(bool chain)
 {
 	TransactionState s = CurrentTransactionState;
 	bool		result = false;
@@ -3678,6 +3733,13 @@ EndTransactionBlock(void)
 			break;
 	}
 
+	Assert(s->blockState == TBLOCK_STARTED ||
+		   s->blockState == TBLOCK_END ||
+		   s->blockState == TBLOCK_ABORT_END ||
+		   s->blockState == TBLOCK_ABORT_PENDING);
+
+	s->chain = chain;
+
 	return result;
 }
 
@@ -3688,7 +3750,7 @@ EndTransactionBlock(void)
  * As above, we don't actually do anything here except change blockState.
  */
 void
-UserAbortTransactionBlock(void)
+UserAbortTransactionBlock(bool chain)
 {
 	TransactionState s = CurrentTransactionState;
 
@@ -3786,6 +3848,11 @@ UserAbortTransactionBlock(void)
 				 BlockStateAsString(s->blockState));
 			break;
 	}
+
+	Assert(s->blockState == TBLOCK_ABORT_END ||
+		   s->blockState == TBLOCK_ABORT_PENDING);
+
+	s->chain = chain;
 }
 
 /*
diff --git a/src/backend/catalog/sql_features.txt b/src/backend/catalog/sql_features.txt
index aeb262a5b0..49df7e08c0 100644
--- a/src/backend/catalog/sql_features.txt
+++ b/src/backend/catalog/sql_features.txt
@@ -443,7 +443,7 @@ T213	INSTEAD OF triggers			YES
 T231	Sensitive cursors			YES	
 T241	START TRANSACTION statement			YES	
 T251	SET TRANSACTION statement: LOCAL option			NO	
-T261	Chained transactions			NO	
+T261	Chained transactions			YES	
 T271	Savepoints			YES	
 T272	Enhanced savepoint management			NO	
 T281	SELECT privilege with column granularity			YES	
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index db49968409..acfb05374d 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -3654,6 +3654,7 @@ _copyTransactionStmt(const TransactionStmt *from)
 	COPY_NODE_FIELD(options);
 	COPY_STRING_FIELD(savepoint_name);
 	COPY_STRING_FIELD(gid);
+	COPY_SCALAR_FIELD(chain);
 
 	return newnode;
 }
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 3a084b4d1f..7c8cc6596d 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -1506,6 +1506,7 @@ _equalTransactionStmt(const TransactionStmt *a, const TransactionStmt *b)
 	COMPARE_NODE_FIELD(options);
 	COMPARE_STRING_FIELD(savepoint_name);
 	COMPARE_STRING_FIELD(gid);
+	COMPARE_SCALAR_FIELD(chain);
 
 	return true;
 }
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 2c2208ffb7..94a407c981 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -310,6 +310,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 %type <boolean>	opt_or_replace
 				opt_grant_grant_option opt_grant_admin_option
 				opt_nowait opt_if_exists opt_with_data
+				opt_transaction_chain
 %type <ival>	opt_nowait_or_skip
 
 %type <list>	OptRoleList AlterOptRoleList
@@ -9807,11 +9808,12 @@ UnlistenStmt:
  *****************************************************************************/
 
 TransactionStmt:
-			ABORT_P opt_transaction
+			ABORT_P opt_transaction opt_transaction_chain
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
 					n->kind = TRANS_STMT_ROLLBACK;
 					n->options = NIL;
+					n->chain = $3;
 					$$ = (Node *)n;
 				}
 			| BEGIN_P opt_transaction transaction_mode_list_or_empty
@@ -9828,25 +9830,28 @@ TransactionStmt:
 					n->options = $3;
 					$$ = (Node *)n;
 				}
-			| COMMIT opt_transaction
+			| COMMIT opt_transaction opt_transaction_chain
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
 					n->kind = TRANS_STMT_COMMIT;
 					n->options = NIL;
+					n->chain = $3;
 					$$ = (Node *)n;
 				}
-			| END_P opt_transaction
+			| END_P opt_transaction opt_transaction_chain
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
 					n->kind = TRANS_STMT_COMMIT;
 					n->options = NIL;
+					n->chain = $3;
 					$$ = (Node *)n;
 				}
-			| ROLLBACK opt_transaction
+			| ROLLBACK opt_transaction opt_transaction_chain
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
 					n->kind = TRANS_STMT_ROLLBACK;
 					n->options = NIL;
+					n->chain = $3;
 					$$ = (Node *)n;
 				}
 			| SAVEPOINT ColId
@@ -9946,6 +9951,12 @@ transaction_mode_list_or_empty:
 					{ $$ = NIL; }
 		;
 
+opt_transaction_chain:
+			AND CHAIN		{ $$ = true; }
+			| AND NO CHAIN	{ $$ = false; }
+			| /* EMPTY */	{ $$ = false; }
+		;
+
 
 /*****************************************************************************
  *
diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c
index 970c94ee80..cd5c536563 100644
--- a/src/backend/tcop/utility.c
+++ b/src/backend/tcop/utility.c
@@ -440,7 +440,7 @@ standard_ProcessUtility(PlannedStmt *pstmt,
 						break;
 
 					case TRANS_STMT_COMMIT:
-						if (!EndTransactionBlock())
+						if (!EndTransactionBlock(stmt->chain))
 						{
 							/* report unsuccessful commit in completionTag */
 							if (completionTag)
@@ -471,7 +471,7 @@ standard_ProcessUtility(PlannedStmt *pstmt,
 						break;
 
 					case TRANS_STMT_ROLLBACK:
-						UserAbortTransactionBlock();
+						UserAbortTransactionBlock(stmt->chain);
 						break;
 
 					case TRANS_STMT_SAVEPOINT:
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index fa44b2820b..fe89c58a7d 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2050,16 +2050,18 @@ psql_completion(const char *text, int start, int end)
 		COMPLETE_WITH("WORK", "TRANSACTION", "ISOLATION LEVEL", "READ", "DEFERRABLE", "NOT DEFERRABLE");
 /* END, ABORT */
 	else if (Matches("END|ABORT"))
-		COMPLETE_WITH("WORK", "TRANSACTION");
+		COMPLETE_WITH("AND", "WORK", "TRANSACTION");
 /* COMMIT */
 	else if (Matches("COMMIT"))
-		COMPLETE_WITH("WORK", "TRANSACTION", "PREPARED");
+		COMPLETE_WITH("AND", "WORK", "TRANSACTION", "PREPARED");
 /* RELEASE SAVEPOINT */
 	else if (Matches("RELEASE"))
 		COMPLETE_WITH("SAVEPOINT");
 /* ROLLBACK */
 	else if (Matches("ROLLBACK"))
-		COMPLETE_WITH("WORK", "TRANSACTION", "TO SAVEPOINT", "PREPARED");
+		COMPLETE_WITH("AND", "WORK", "TRANSACTION", "TO SAVEPOINT", "PREPARED");
+	else if (Matches("ABORT|END|COMMIT|ROLLBACK", "AND"))
+		COMPLETE_WITH("CHAIN");
 /* CALL */
 	else if (Matches("CALL"))
 		COMPLETE_WITH_VERSIONED_SCHEMA_QUERY(Query_for_list_of_procedures, NULL);
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 689c57c592..c757146e4d 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -372,9 +372,9 @@ extern void StartTransactionCommand(void);
 extern void CommitTransactionCommand(void);
 extern void AbortCurrentTransaction(void);
 extern void BeginTransactionBlock(void);
-extern bool EndTransactionBlock(void);
+extern bool EndTransactionBlock(bool chain);
 extern bool PrepareTransactionBlock(const char *gid);
-extern void UserAbortTransactionBlock(void);
+extern void UserAbortTransactionBlock(bool chain);
 extern void BeginImplicitTransactionBlock(void);
 extern void EndImplicitTransactionBlock(void);
 extern void ReleaseSavepoint(const char *name);
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index e5bdc1cec5..bcc2f1a06c 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2986,6 +2986,7 @@ typedef struct TransactionStmt
 	List	   *options;		/* for BEGIN/START commands */
 	char	   *savepoint_name; /* for savepoint commands */
 	char	   *gid;			/* for two-phase-commit related commands */
+	bool		chain;			/* AND CHAIN option */
 } TransactionStmt;
 
 /* ----------------------
diff --git a/src/test/regress/expected/transactions.out b/src/test/regress/expected/transactions.out
index 69e176c525..4093b6fdf0 100644
--- a/src/test/regress/expected/transactions.out
+++ b/src/test/regress/expected/transactions.out
@@ -659,6 +659,197 @@ ERROR:  portal "ctt" cannot be run
 COMMIT;
 DROP FUNCTION create_temp_tab();
 DROP FUNCTION invert(x float8);
+-- Tests for AND CHAIN
+CREATE TABLE abc (a int);
+-- set nondefault value so we have something to override below
+SET default_transaction_read_only = on;
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ, READ WRITE, DEFERRABLE;
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ on
+(1 row)
+
+INSERT INTO abc VALUES (1);
+INSERT INTO abc VALUES (2);
+COMMIT AND CHAIN;  -- TBLOCK_END
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ on
+(1 row)
+
+INSERT INTO abc VALUES ('error');
+ERROR:  invalid input syntax for type integer: "error"
+LINE 1: INSERT INTO abc VALUES ('error');
+                                ^
+INSERT INTO abc VALUES (3);  -- check it's really aborted
+ERROR:  current transaction is aborted, commands ignored until end of transaction block
+COMMIT AND CHAIN;  -- TBLOCK_ABORT_END
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ on
+(1 row)
+
+INSERT INTO abc VALUES (3);
+COMMIT;
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ, READ WRITE, DEFERRABLE;
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ on
+(1 row)
+
+SAVEPOINT x;
+INSERT INTO abc VALUES ('error');
+ERROR:  invalid input syntax for type integer: "error"
+LINE 1: INSERT INTO abc VALUES ('error');
+                                ^
+COMMIT AND CHAIN;  -- TBLOCK_ABORT_PENDING
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ on
+(1 row)
+
+INSERT INTO abc VALUES (4);
+COMMIT;
+-- different mix of options just for fun
+START TRANSACTION ISOLATION LEVEL SERIALIZABLE, READ WRITE, NOT DEFERRABLE;
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ serializable
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ off
+(1 row)
+
+INSERT INTO abc VALUES (5);
+ROLLBACK AND CHAIN;  -- TBLOCK_ABORT_PENDING
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ serializable
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ off
+(1 row)
+
+INSERT INTO abc VALUES ('error');
+ERROR:  invalid input syntax for type integer: "error"
+LINE 1: INSERT INTO abc VALUES ('error');
+                                ^
+ROLLBACK AND CHAIN;  -- TBLOCK_ABORT_END
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ serializable
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ off
+(1 row)
+
+ROLLBACK;
+SELECT * FROM abc ORDER BY 1;
+ a 
+---
+ 1
+ 2
+ 3
+ 4
+(4 rows)
+
+RESET default_transaction_read_only;
+DROP TABLE abc;
 -- Test assorted behaviors around the implicit transaction block created
 -- when multiple SQL commands are sent in a single Query message.  These
 -- tests rely on the fact that psql will not break SQL commands apart at a
diff --git a/src/test/regress/sql/transactions.sql b/src/test/regress/sql/transactions.sql
index 2e3739fd6c..8e89481430 100644
--- a/src/test/regress/sql/transactions.sql
+++ b/src/test/regress/sql/transactions.sql
@@ -419,6 +419,69 @@ CREATE FUNCTION create_temp_tab() RETURNS text
 DROP FUNCTION invert(x float8);
 
 
+-- Tests for AND CHAIN
+
+CREATE TABLE abc (a int);
+
+-- set nondefault value so we have something to override below
+SET default_transaction_read_only = on;
+
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ, READ WRITE, DEFERRABLE;
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES (1);
+INSERT INTO abc VALUES (2);
+COMMIT AND CHAIN;  -- TBLOCK_END
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES ('error');
+INSERT INTO abc VALUES (3);  -- check it's really aborted
+COMMIT AND CHAIN;  -- TBLOCK_ABORT_END
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES (3);
+COMMIT;
+
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ, READ WRITE, DEFERRABLE;
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+SAVEPOINT x;
+INSERT INTO abc VALUES ('error');
+COMMIT AND CHAIN;  -- TBLOCK_ABORT_PENDING
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES (4);
+COMMIT;
+
+-- different mix of options just for fun
+START TRANSACTION ISOLATION LEVEL SERIALIZABLE, READ WRITE, NOT DEFERRABLE;
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES (5);
+ROLLBACK AND CHAIN;  -- TBLOCK_ABORT_PENDING
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES ('error');
+ROLLBACK AND CHAIN;  -- TBLOCK_ABORT_END
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+ROLLBACK;
+
+SELECT * FROM abc ORDER BY 1;
+
+RESET default_transaction_read_only;
+
+DROP TABLE abc;
+
+
 -- Test assorted behaviors around the implicit transaction block created
 -- when multiple SQL commands are sent in a single Query message.  These
 -- tests rely on the fact that psql will not break SQL commands apart at a

base-commit: f2cbffc7a6183a359b339cfed65e9d609de756f0
-- 
2.19.1

From 26079769e5896766c9e322f07480dd280f51b804 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter_e@gmx.net>
Date: Wed, 28 Feb 2018 10:04:06 -0500
Subject: [PATCH v3 2/2] Transaction chaining support in PL/pgSQL

---
 doc/src/sgml/plpgsql.sgml                     |  9 ++++++
 doc/src/sgml/spi.sgml                         | 14 ++++++---
 src/backend/access/transam/xact.c             |  4 +--
 src/backend/executor/spi.c                    | 24 ++++++++++++--
 src/include/access/xact.h                     |  2 ++
 src/include/executor/spi.h                    |  4 +--
 src/pl/plperl/plperl.c                        |  4 +--
 .../src/expected/plpgsql_transaction.out      | 31 +++++++++++++++++++
 src/pl/plpgsql/src/pl_exec.c                  | 10 +++---
 src/pl/plpgsql/src/pl_funcs.c                 | 10 ++++--
 src/pl/plpgsql/src/pl_gram.y                  | 18 +++++++++--
 src/pl/plpgsql/src/pl_scanner.c               |  2 ++
 src/pl/plpgsql/src/plpgsql.h                  |  2 ++
 .../plpgsql/src/sql/plpgsql_transaction.sql   | 23 ++++++++++++++
 src/pl/plpython/plpy_plpymodule.c             |  4 +--
 src/pl/tcl/pltcl.c                            |  4 +--
 16 files changed, 141 insertions(+), 24 deletions(-)

diff --git a/doc/src/sgml/plpgsql.sgml b/doc/src/sgml/plpgsql.sgml
index b9eb98cfd7..128f13742a 100644
--- a/doc/src/sgml/plpgsql.sgml
+++ b/doc/src/sgml/plpgsql.sgml
@@ -3490,6 +3490,15 @@ <title>Transaction Management</title>
 </programlisting>
    </para>
 
+   <para>
+    A new transaction starts out with default transaction characteristics such
+    as transaction isolation level.  In cases where transactions are committed
+    in a loop, it might be desirable to start new transactions automatically
+    with the same characteristics as the previous one.  The commands
+    <command>COMMIT AND CHAIN</command> and <command>ROLLBACK AND
+    CHAIN</command> accomplish this.
+   </para>
+
    <para>
     Transaction control is only possible in <command>CALL</command> or
     <command>DO</command> invocations from the top level or nested
diff --git a/doc/src/sgml/spi.sgml b/doc/src/sgml/spi.sgml
index 9db11d22fb..9b4e63e352 100644
--- a/doc/src/sgml/spi.sgml
+++ b/doc/src/sgml/spi.sgml
@@ -4389,7 +4389,7 @@ <title>Transaction Management</title>
 
  <refsynopsisdiv>
 <synopsis>
-void SPI_commit(void)
+void SPI_commit(bool <parameter>chain</parameter>)
 </synopsis>
  </refsynopsisdiv>
 
@@ -4402,7 +4402,10 @@ <title>Description</title>
    command <command>COMMIT</command>.  After a transaction is committed, a new
    transaction has to be started
    using <function>SPI_start_transaction</function> before further database
-   actions can be executed.
+   actions can be executed.  If <parameter>chain</parameter> is true, then a
+   new transaction is immediately started with the same transaction
+   characteristics as the just finished one, like with the SQL command
+   <command>COMMIT AND CHAIN</command>.
   </para>
 
   <para>
@@ -4429,7 +4432,7 @@ <title>Description</title>
 
  <refsynopsisdiv>
 <synopsis>
-void SPI_rollback(void)
+void SPI_rollback(bool <parameter>chain</parameter>)
 </synopsis>
  </refsynopsisdiv>
 
@@ -4442,7 +4445,10 @@ <title>Description</title>
    command <command>ROLLBACK</command>.  After a transaction is rolled back, a
    new transaction has to be started
    using <function>SPI_start_transaction</function> before further database
-   actions can be executed.
+   actions can be executed.  If <parameter>chain</parameter> is true, then a
+   new transaction is immediately started with the same transaction
+   characteristics as the just finished one, like with the SQL command
+   <command>COMMIT AND CHAIN</command>.
   </para>
 
   <para>
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6af149d788..e8c2db3c2d 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -2774,7 +2774,7 @@ static int	save_XactIsoLevel;
 static bool	save_XactReadOnly;
 static bool	save_XactDeferrable;
 
-static void
+void
 SaveTransactionCharacteristics(void)
 {
 	save_XactIsoLevel = XactIsoLevel;
@@ -2782,7 +2782,7 @@ SaveTransactionCharacteristics(void)
 	save_XactDeferrable = XactDeferrable;
 }
 
-static void
+void
 RestoreTransactionCharacteristics(void)
 {
 	XactIsoLevel = save_XactIsoLevel;
diff --git a/src/backend/executor/spi.c b/src/backend/executor/spi.c
index ad726676d8..d61a56e095 100644
--- a/src/backend/executor/spi.c
+++ b/src/backend/executor/spi.c
@@ -218,7 +218,7 @@ SPI_start_transaction(void)
 }
 
 void
-SPI_commit(void)
+SPI_commit(bool chain)
 {
 	MemoryContext oldcontext = CurrentMemoryContext;
 
@@ -250,14 +250,24 @@ SPI_commit(void)
 	while (ActiveSnapshotSet())
 		PopActiveSnapshot();
 
+	if (chain)
+		SaveTransactionCharacteristics();
+
 	CommitTransactionCommand();
+
+	if (chain)
+	{
+		StartTransactionCommand();
+		RestoreTransactionCharacteristics();
+	}
+
 	MemoryContextSwitchTo(oldcontext);
 
 	_SPI_current->internal_xact = false;
 }
 
 void
-SPI_rollback(void)
+SPI_rollback(bool chain)
 {
 	MemoryContext oldcontext = CurrentMemoryContext;
 
@@ -274,7 +284,17 @@ SPI_rollback(void)
 
 	_SPI_current->internal_xact = true;
 
+	if (chain)
+		SaveTransactionCharacteristics();
+
 	AbortCurrentTransaction();
+
+	if (chain)
+	{
+		StartTransactionCommand();
+		RestoreTransactionCharacteristics();
+	}
+
 	MemoryContextSwitchTo(oldcontext);
 
 	_SPI_current->internal_xact = false;
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index c757146e4d..2abdbece6c 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -369,6 +369,8 @@ extern bool TransactionIdIsCurrentTransactionId(TransactionId xid);
 extern void CommandCounterIncrement(void);
 extern void ForceSyncCommit(void);
 extern void StartTransactionCommand(void);
+extern void SaveTransactionCharacteristics(void);
+extern void RestoreTransactionCharacteristics(void);
 extern void CommitTransactionCommand(void);
 extern void AbortCurrentTransaction(void);
 extern void BeginTransactionBlock(void);
diff --git a/src/include/executor/spi.h b/src/include/executor/spi.h
index d2616968ac..6bf2acb3b5 100644
--- a/src/include/executor/spi.h
+++ b/src/include/executor/spi.h
@@ -159,8 +159,8 @@ extern int	SPI_unregister_relation(const char *name);
 extern int	SPI_register_trigger_data(TriggerData *tdata);
 
 extern void SPI_start_transaction(void);
-extern void SPI_commit(void);
-extern void SPI_rollback(void);
+extern void SPI_commit(bool chain);
+extern void SPI_rollback(bool chain);
 
 extern void SPICleanup(void);
 extern void AtEOXact_SPI(bool isCommit);
diff --git a/src/pl/plperl/plperl.c b/src/pl/plperl/plperl.c
index fe54b20903..93190d1099 100644
--- a/src/pl/plperl/plperl.c
+++ b/src/pl/plperl/plperl.c
@@ -3968,7 +3968,7 @@ plperl_spi_commit(void)
 	{
 		HoldPinnedPortals();
 
-		SPI_commit();
+		SPI_commit(false);
 		SPI_start_transaction();
 	}
 	PG_CATCH();
@@ -3995,7 +3995,7 @@ plperl_spi_rollback(void)
 	{
 		HoldPinnedPortals();
 
-		SPI_rollback();
+		SPI_rollback(false);
 		SPI_start_transaction();
 	}
 	PG_CATCH();
diff --git a/src/pl/plpgsql/src/expected/plpgsql_transaction.out b/src/pl/plpgsql/src/expected/plpgsql_transaction.out
index 6eedb215a4..ab62437bde 100644
--- a/src/pl/plpgsql/src/expected/plpgsql_transaction.out
+++ b/src/pl/plpgsql/src/expected/plpgsql_transaction.out
@@ -523,6 +523,37 @@ BEGIN
 END;
 $$;
 CALL transaction_test11();
+-- transaction chain
+TRUNCATE test1;
+DO LANGUAGE plpgsql $$
+BEGIN
+    ROLLBACK;
+    SET TRANSACTION ISOLATION LEVEL REPEATABLE READ;
+    FOR i IN 0..5 LOOP
+        RAISE INFO 'transaction_isolation = %', current_setting('transaction_isolation');
+        INSERT INTO test1 (a) VALUES (i);
+        IF i % 2 = 0 THEN
+            COMMIT AND CHAIN;
+        ELSE
+            ROLLBACK AND CHAIN;
+        END IF;
+    END LOOP;
+END
+$$;
+INFO:  transaction_isolation = repeatable read
+INFO:  transaction_isolation = repeatable read
+INFO:  transaction_isolation = repeatable read
+INFO:  transaction_isolation = repeatable read
+INFO:  transaction_isolation = repeatable read
+INFO:  transaction_isolation = repeatable read
+SELECT * FROM test1;
+ a | b 
+---+---
+ 0 | 
+ 2 | 
+ 4 | 
+(3 rows)
+
 DROP TABLE test1;
 DROP TABLE test2;
 DROP TABLE test3;
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index 39ea925820..04f5ec603c 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -4773,8 +4773,9 @@ exec_stmt_commit(PLpgSQL_execstate *estate, PLpgSQL_stmt_commit *stmt)
 {
 	HoldPinnedPortals();
 
-	SPI_commit();
-	SPI_start_transaction();
+	SPI_commit(stmt->chain);
+	if (!stmt->chain)
+		SPI_start_transaction();
 
 	estate->simple_eval_estate = NULL;
 	plpgsql_create_econtext(estate);
@@ -4792,8 +4793,9 @@ exec_stmt_rollback(PLpgSQL_execstate *estate, PLpgSQL_stmt_rollback *stmt)
 {
 	HoldPinnedPortals();
 
-	SPI_rollback();
-	SPI_start_transaction();
+	SPI_rollback(stmt->chain);
+	if (!stmt->chain)
+		SPI_start_transaction();
 
 	estate->simple_eval_estate = NULL;
 	plpgsql_create_econtext(estate);
diff --git a/src/pl/plpgsql/src/pl_funcs.c b/src/pl/plpgsql/src/pl_funcs.c
index 4266e6cee7..0b0f892e2d 100644
--- a/src/pl/plpgsql/src/pl_funcs.c
+++ b/src/pl/plpgsql/src/pl_funcs.c
@@ -1318,14 +1318,20 @@ static void
 dump_commit(PLpgSQL_stmt_commit *stmt)
 {
 	dump_ind();
-	printf("COMMIT\n");
+	if (stmt->chain)
+		printf("COMMIT AND CHAIN\n");
+	else
+		printf("COMMIT\n");
 }
 
 static void
 dump_rollback(PLpgSQL_stmt_rollback *stmt)
 {
 	dump_ind();
-	printf("ROLLBACK\n");
+	if (stmt->chain)
+		printf("ROLLBACK AND CHAIN\n");
+	else
+		printf("ROLLBACK\n");
 }
 
 static void
diff --git a/src/pl/plpgsql/src/pl_gram.y b/src/pl/plpgsql/src/pl_gram.y
index a979a5109d..924fbeb263 100644
--- a/src/pl/plpgsql/src/pl_gram.y
+++ b/src/pl/plpgsql/src/pl_gram.y
@@ -219,6 +219,8 @@ static	void			check_raise_parameters(PLpgSQL_stmt_raise *stmt);
 %type <ival>	opt_scrollable
 %type <fetch>	opt_fetch_direction
 
+%type <ival>	opt_transaction_chain
+
 %type <keyword>	unreserved_keyword
 
 
@@ -252,6 +254,7 @@ static	void			check_raise_parameters(PLpgSQL_stmt_raise *stmt);
 %token <keyword>	K_ABSOLUTE
 %token <keyword>	K_ALIAS
 %token <keyword>	K_ALL
+%token <keyword>	K_AND
 %token <keyword>	K_ARRAY
 %token <keyword>	K_ASSERT
 %token <keyword>	K_BACKWARD
@@ -259,6 +262,7 @@ static	void			check_raise_parameters(PLpgSQL_stmt_raise *stmt);
 %token <keyword>	K_BY
 %token <keyword>	K_CALL
 %token <keyword>	K_CASE
+%token <keyword>	K_CHAIN
 %token <keyword>	K_CLOSE
 %token <keyword>	K_COLLATE
 %token <keyword>	K_COLUMN
@@ -2177,30 +2181,38 @@ stmt_null		: K_NULL ';'
 					}
 				;
 
-stmt_commit		: K_COMMIT ';'
+stmt_commit		: K_COMMIT opt_transaction_chain ';'
 					{
 						PLpgSQL_stmt_commit *new;
 
 						new = palloc(sizeof(PLpgSQL_stmt_commit));
 						new->cmd_type = PLPGSQL_STMT_COMMIT;
 						new->lineno = plpgsql_location_to_lineno(@1);
+						new->chain = $2;
 
 						$$ = (PLpgSQL_stmt *)new;
 					}
 				;
 
-stmt_rollback	: K_ROLLBACK ';'
+stmt_rollback	: K_ROLLBACK opt_transaction_chain ';'
 					{
 						PLpgSQL_stmt_rollback *new;
 
 						new = palloc(sizeof(PLpgSQL_stmt_rollback));
 						new->cmd_type = PLPGSQL_STMT_ROLLBACK;
 						new->lineno = plpgsql_location_to_lineno(@1);
+						new->chain = $2;
 
 						$$ = (PLpgSQL_stmt *)new;
 					}
 				;
 
+opt_transaction_chain:
+			K_AND K_CHAIN			{ $$ = true; }
+			| K_AND K_NO K_CHAIN	{ $$ = false; }
+			| /* EMPTY */			{ $$ = false; }
+				;
+
 stmt_set	: K_SET
 					{
 						PLpgSQL_stmt_set *new;
@@ -2455,10 +2467,12 @@ any_identifier	: T_WORD
 unreserved_keyword	:
 				K_ABSOLUTE
 				| K_ALIAS
+				| K_AND
 				| K_ARRAY
 				| K_ASSERT
 				| K_BACKWARD
 				| K_CALL
+				| K_CHAIN
 				| K_CLOSE
 				| K_COLLATE
 				| K_COLUMN
diff --git a/src/pl/plpgsql/src/pl_scanner.c b/src/pl/plpgsql/src/pl_scanner.c
index ab18946847..d4000bcaaa 100644
--- a/src/pl/plpgsql/src/pl_scanner.c
+++ b/src/pl/plpgsql/src/pl_scanner.c
@@ -99,10 +99,12 @@ static const int num_reserved_keywords = lengthof(reserved_keywords);
 static const ScanKeyword unreserved_keywords[] = {
 	PG_KEYWORD("absolute", K_ABSOLUTE, UNRESERVED_KEYWORD)
 	PG_KEYWORD("alias", K_ALIAS, UNRESERVED_KEYWORD)
+	PG_KEYWORD("and", K_AND, UNRESERVED_KEYWORD)
 	PG_KEYWORD("array", K_ARRAY, UNRESERVED_KEYWORD)
 	PG_KEYWORD("assert", K_ASSERT, UNRESERVED_KEYWORD)
 	PG_KEYWORD("backward", K_BACKWARD, UNRESERVED_KEYWORD)
 	PG_KEYWORD("call", K_CALL, UNRESERVED_KEYWORD)
+	PG_KEYWORD("chain", K_CHAIN, UNRESERVED_KEYWORD)
 	PG_KEYWORD("close", K_CLOSE, UNRESERVED_KEYWORD)
 	PG_KEYWORD("collate", K_COLLATE, UNRESERVED_KEYWORD)
 	PG_KEYWORD("column", K_COLUMN, UNRESERVED_KEYWORD)
diff --git a/src/pl/plpgsql/src/plpgsql.h b/src/pl/plpgsql/src/plpgsql.h
index 42177ccaa6..cac14e87d8 100644
--- a/src/pl/plpgsql/src/plpgsql.h
+++ b/src/pl/plpgsql/src/plpgsql.h
@@ -533,6 +533,7 @@ typedef struct PLpgSQL_stmt_commit
 {
 	PLpgSQL_stmt_type cmd_type;
 	int			lineno;
+	bool		chain;
 } PLpgSQL_stmt_commit;
 
 /*
@@ -542,6 +543,7 @@ typedef struct PLpgSQL_stmt_rollback
 {
 	PLpgSQL_stmt_type cmd_type;
 	int			lineno;
+	bool		chain;
 } PLpgSQL_stmt_rollback;
 
 /*
diff --git a/src/pl/plpgsql/src/sql/plpgsql_transaction.sql b/src/pl/plpgsql/src/sql/plpgsql_transaction.sql
index ac1361a8ce..304bb3ffa8 100644
--- a/src/pl/plpgsql/src/sql/plpgsql_transaction.sql
+++ b/src/pl/plpgsql/src/sql/plpgsql_transaction.sql
@@ -445,6 +445,29 @@ CREATE PROCEDURE transaction_test11()
 CALL transaction_test11();
 
 
+-- transaction chain
+
+TRUNCATE test1;
+
+DO LANGUAGE plpgsql $$
+BEGIN
+    ROLLBACK;
+    SET TRANSACTION ISOLATION LEVEL REPEATABLE READ;
+    FOR i IN 0..5 LOOP
+        RAISE INFO 'transaction_isolation = %', current_setting('transaction_isolation');
+        INSERT INTO test1 (a) VALUES (i);
+        IF i % 2 = 0 THEN
+            COMMIT AND CHAIN;
+        ELSE
+            ROLLBACK AND CHAIN;
+        END IF;
+    END LOOP;
+END
+$$;
+
+SELECT * FROM test1;
+
+
 DROP TABLE test1;
 DROP TABLE test2;
 DROP TABLE test3;
diff --git a/src/pl/plpython/plpy_plpymodule.c b/src/pl/plpython/plpy_plpymodule.c
index 23e49e4b75..729f402ea1 100644
--- a/src/pl/plpython/plpy_plpymodule.c
+++ b/src/pl/plpython/plpy_plpymodule.c
@@ -590,7 +590,7 @@ PLy_commit(PyObject *self, PyObject *args)
 
 	HoldPinnedPortals();
 
-	SPI_commit();
+	SPI_commit(false);
 	SPI_start_transaction();
 
 	/* was cleared at transaction end, reset pointer */
@@ -606,7 +606,7 @@ PLy_rollback(PyObject *self, PyObject *args)
 
 	HoldPinnedPortals();
 
-	SPI_rollback();
+	SPI_rollback(false);
 	SPI_start_transaction();
 
 	/* was cleared at transaction end, reset pointer */
diff --git a/src/pl/tcl/pltcl.c b/src/pl/tcl/pltcl.c
index 3b1454f833..27fa0fa53a 100644
--- a/src/pl/tcl/pltcl.c
+++ b/src/pl/tcl/pltcl.c
@@ -2931,7 +2931,7 @@ pltcl_commit(ClientData cdata, Tcl_Interp *interp,
 
 	PG_TRY();
 	{
-		SPI_commit();
+		SPI_commit(false);
 		SPI_start_transaction();
 	}
 	PG_CATCH();
@@ -2971,7 +2971,7 @@ pltcl_rollback(ClientData cdata, Tcl_Interp *interp,
 
 	PG_TRY();
 	{
-		SPI_rollback();
+		SPI_rollback(false);
 		SPI_start_transaction();
 	}
 	PG_CATCH();
-- 
2.19.1

From ec4e153976f21d48f66bde1403d569ce63f8638e Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 2 Jan 2019 15:09:04 +0100
Subject: [PATCH v4 1/2] Transaction chaining

Add command variants COMMIT AND CHAIN and ROLLBACK AND CHAIN, which
start new transactions with the same transaction characteristics as the
just finished one, per SQL standard.
---
 doc/src/sgml/ref/abort.sgml                |  14 +-
 doc/src/sgml/ref/commit.sgml               |  19 +-
 doc/src/sgml/ref/end.sgml                  |  14 +-
 doc/src/sgml/ref/rollback.sgml             |  19 +-
 src/backend/access/transam/xact.c          |  73 +++++++-
 src/backend/catalog/sql_features.txt       |   2 +-
 src/backend/nodes/copyfuncs.c              |   1 +
 src/backend/nodes/equalfuncs.c             |   1 +
 src/backend/parser/gram.y                  |  19 +-
 src/backend/tcop/utility.c                 |   4 +-
 src/bin/psql/tab-complete.c                |   8 +-
 src/include/access/xact.h                  |   4 +-
 src/include/nodes/parsenodes.h             |   1 +
 src/test/regress/expected/transactions.out | 191 +++++++++++++++++++++
 src/test/regress/sql/transactions.sql      |  63 +++++++
 15 files changed, 408 insertions(+), 25 deletions(-)

diff --git a/doc/src/sgml/ref/abort.sgml b/doc/src/sgml/ref/abort.sgml
index 21799d2a83..0372913365 100644
--- a/doc/src/sgml/ref/abort.sgml
+++ b/doc/src/sgml/ref/abort.sgml
@@ -21,7 +21,7 @@
 
  <refsynopsisdiv>
 <synopsis>
-ABORT [ WORK | TRANSACTION ]
+ABORT [ WORK | TRANSACTION ] [ AND [ NO ] CHAIN ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -51,6 +51,18 @@ <title>Parameters</title>
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term><literal>AND CHAIN</literal></term>
+    <listitem>
+     <para>
+      If <literal>AND CHAIN</literal> is specified, a new transaction is
+      immediately started with the same transaction characteristics (see <xref
+      linkend="sql-set-transaction"/>) as the just finished one.  Otherwise,
+      no new transaction is started.
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
  </refsect1>
 
diff --git a/doc/src/sgml/ref/commit.sgml b/doc/src/sgml/ref/commit.sgml
index b2e8d5d180..96a018e6aa 100644
--- a/doc/src/sgml/ref/commit.sgml
+++ b/doc/src/sgml/ref/commit.sgml
@@ -21,7 +21,7 @@
 
  <refsynopsisdiv>
 <synopsis>
-COMMIT [ WORK | TRANSACTION ]
+COMMIT [ WORK | TRANSACTION ] [ AND [ NO ] CHAIN ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -48,6 +48,18 @@ <title>Parameters</title>
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term><literal>AND CHAIN</literal></term>
+    <listitem>
+     <para>
+      If <literal>AND CHAIN</literal> is specified, a new transaction is
+      immediately started with the same transaction characteristics (see <xref
+      linkend="sql-set-transaction"/>) as the just finished one.  Otherwise,
+      no new transaction is started.
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
  </refsect1>
 
@@ -79,9 +91,8 @@ <title>Examples</title>
   <title>Compatibility</title>
 
   <para>
-   The SQL standard only specifies the two forms
-   <literal>COMMIT</literal> and <literal>COMMIT
-   WORK</literal>. Otherwise, this command is fully conforming.
+   The command <command>COMMIT</command> conforms to the SQL standard.  The
+   form <literal>COMMIT TRANSACTION</literal> is a PostgreSQL extension.
   </para>
  </refsect1>
 
diff --git a/doc/src/sgml/ref/end.sgml b/doc/src/sgml/ref/end.sgml
index 7523315f34..8b8f4f0dbb 100644
--- a/doc/src/sgml/ref/end.sgml
+++ b/doc/src/sgml/ref/end.sgml
@@ -21,7 +21,7 @@
 
  <refsynopsisdiv>
 <synopsis>
-END [ WORK | TRANSACTION ]
+END [ WORK | TRANSACTION ] [ AND [ NO ] CHAIN ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -50,6 +50,18 @@ <title>Parameters</title>
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term><literal>AND CHAIN</literal></term>
+    <listitem>
+     <para>
+      If <literal>AND CHAIN</literal> is specified, a new transaction is
+      immediately started with the same transaction characteristics (see <xref
+      linkend="sql-set-transaction"/>) as the just finished one.  Otherwise,
+      no new transaction is started.
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
  </refsect1>
 
diff --git a/doc/src/sgml/ref/rollback.sgml b/doc/src/sgml/ref/rollback.sgml
index 3cafb848a9..54fffefe18 100644
--- a/doc/src/sgml/ref/rollback.sgml
+++ b/doc/src/sgml/ref/rollback.sgml
@@ -21,7 +21,7 @@
 
  <refsynopsisdiv>
 <synopsis>
-ROLLBACK [ WORK | TRANSACTION ]
+ROLLBACK [ WORK | TRANSACTION ] [ AND [ NO ] CHAIN ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -47,6 +47,18 @@ <title>Parameters</title>
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term><literal>AND CHAIN</literal></term>
+    <listitem>
+     <para>
+      If <literal>AND CHAIN</literal> is specified, a new transaction is
+      immediately started with the same transaction characteristics (see <xref
+      linkend="sql-set-transaction"/>) as the just finished one.  Otherwise,
+      no new transaction is started.
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
  </refsect1>
 
@@ -78,9 +90,8 @@ <title>Examples</title>
   <title>Compatibility</title>
 
   <para>
-   The SQL standard only specifies the two forms
-   <literal>ROLLBACK</literal> and <literal>ROLLBACK
-   WORK</literal>. Otherwise, this command is fully conforming.
+   The command <command>ROLLBACK</command> conforms to the SQL standard.  The
+   form <literal>ROLLBACK TRANSACTION</literal> is a PostgreSQL extension.
   </para>
  </refsect1>
 
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index d967400384..6af149d788 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -189,6 +189,7 @@ typedef struct TransactionStateData
 	bool		startedInRecovery;	/* did we start in recovery? */
 	bool		didLogXid;		/* has xid been included in WAL record? */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
+	bool		chain;			/* start a new block after this one */
 	struct TransactionStateData *parent;	/* back link to parent */
 } TransactionStateData;
 
@@ -2760,6 +2761,36 @@ StartTransactionCommand(void)
 	MemoryContextSwitchTo(CurTransactionContext);
 }
 
+
+/*
+ * Simple system for saving and restoring transaction characteristics
+ * (isolation level, read only, deferrable).  We need this for transaction
+ * chaining, so that we can set the characteristics of the new transaction to
+ * be the same as the previous one.  (We need something like this because the
+ * GUC system resets the characteristics at transaction end, so for example
+ * just skipping the reset in StartTransaction() won't work.)
+ */
+static int	save_XactIsoLevel;
+static bool	save_XactReadOnly;
+static bool	save_XactDeferrable;
+
+static void
+SaveTransactionCharacteristics(void)
+{
+	save_XactIsoLevel = XactIsoLevel;
+	save_XactReadOnly = XactReadOnly;
+	save_XactDeferrable = XactDeferrable;
+}
+
+static void
+RestoreTransactionCharacteristics(void)
+{
+	XactIsoLevel = save_XactIsoLevel;
+	XactReadOnly = save_XactReadOnly;
+	XactDeferrable = save_XactDeferrable;
+}
+
+
 /*
  *	CommitTransactionCommand
  */
@@ -2768,6 +2799,9 @@ CommitTransactionCommand(void)
 {
 	TransactionState s = CurrentTransactionState;
 
+	if (s->chain)
+		SaveTransactionCharacteristics();
+
 	switch (s->blockState)
 	{
 			/*
@@ -2819,6 +2853,13 @@ CommitTransactionCommand(void)
 		case TBLOCK_END:
 			CommitTransaction();
 			s->blockState = TBLOCK_DEFAULT;
+			if (s->chain)
+			{
+				StartTransaction();
+				s->blockState = TBLOCK_INPROGRESS;
+				s->chain = false;
+				RestoreTransactionCharacteristics();
+			}
 			break;
 
 			/*
@@ -2838,6 +2879,13 @@ CommitTransactionCommand(void)
 		case TBLOCK_ABORT_END:
 			CleanupTransaction();
 			s->blockState = TBLOCK_DEFAULT;
+			if (s->chain)
+			{
+				StartTransaction();
+				s->blockState = TBLOCK_INPROGRESS;
+				s->chain = false;
+				RestoreTransactionCharacteristics();
+			}
 			break;
 
 			/*
@@ -2849,6 +2897,13 @@ CommitTransactionCommand(void)
 			AbortTransaction();
 			CleanupTransaction();
 			s->blockState = TBLOCK_DEFAULT;
+			if (s->chain)
+			{
+				StartTransaction();
+				s->blockState = TBLOCK_INPROGRESS;
+				s->chain = false;
+				RestoreTransactionCharacteristics();
+			}
 			break;
 
 			/*
@@ -3506,7 +3561,7 @@ PrepareTransactionBlock(const char *gid)
 	bool		result;
 
 	/* Set up to commit the current transaction */
-	result = EndTransactionBlock();
+	result = EndTransactionBlock(false);
 
 	/* If successful, change outer tblock state to PREPARE */
 	if (result)
@@ -3552,7 +3607,7 @@ PrepareTransactionBlock(const char *gid)
  * resource owner, etc while executing inside a Portal.
  */
 bool
-EndTransactionBlock(void)
+EndTransactionBlock(bool chain)
 {
 	TransactionState s = CurrentTransactionState;
 	bool		result = false;
@@ -3678,6 +3733,13 @@ EndTransactionBlock(void)
 			break;
 	}
 
+	Assert(s->blockState == TBLOCK_STARTED ||
+		   s->blockState == TBLOCK_END ||
+		   s->blockState == TBLOCK_ABORT_END ||
+		   s->blockState == TBLOCK_ABORT_PENDING);
+
+	s->chain = chain;
+
 	return result;
 }
 
@@ -3688,7 +3750,7 @@ EndTransactionBlock(void)
  * As above, we don't actually do anything here except change blockState.
  */
 void
-UserAbortTransactionBlock(void)
+UserAbortTransactionBlock(bool chain)
 {
 	TransactionState s = CurrentTransactionState;
 
@@ -3786,6 +3848,11 @@ UserAbortTransactionBlock(void)
 				 BlockStateAsString(s->blockState));
 			break;
 	}
+
+	Assert(s->blockState == TBLOCK_ABORT_END ||
+		   s->blockState == TBLOCK_ABORT_PENDING);
+
+	s->chain = chain;
 }
 
 /*
diff --git a/src/backend/catalog/sql_features.txt b/src/backend/catalog/sql_features.txt
index aeb262a5b0..49df7e08c0 100644
--- a/src/backend/catalog/sql_features.txt
+++ b/src/backend/catalog/sql_features.txt
@@ -443,7 +443,7 @@ T213	INSTEAD OF triggers			YES
 T231	Sensitive cursors			YES	
 T241	START TRANSACTION statement			YES	
 T251	SET TRANSACTION statement: LOCAL option			NO	
-T261	Chained transactions			NO	
+T261	Chained transactions			YES	
 T271	Savepoints			YES	
 T272	Enhanced savepoint management			NO	
 T281	SELECT privilege with column granularity			YES	
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index 144cd7a047..35d28c6d7b 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -3653,6 +3653,7 @@ _copyTransactionStmt(const TransactionStmt *from)
 	COPY_NODE_FIELD(options);
 	COPY_STRING_FIELD(savepoint_name);
 	COPY_STRING_FIELD(gid);
+	COPY_SCALAR_FIELD(chain);
 
 	return newnode;
 }
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index c4579fbcc6..44e5dcc8d7 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -1506,6 +1506,7 @@ _equalTransactionStmt(const TransactionStmt *a, const TransactionStmt *b)
 	COMPARE_NODE_FIELD(options);
 	COMPARE_STRING_FIELD(savepoint_name);
 	COMPARE_STRING_FIELD(gid);
+	COMPARE_SCALAR_FIELD(chain);
 
 	return true;
 }
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 5bcaf42205..f8bc2855b5 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -310,6 +310,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 %type <boolean>	opt_or_replace
 				opt_grant_grant_option opt_grant_admin_option
 				opt_nowait opt_if_exists opt_with_data
+				opt_transaction_chain
 %type <ival>	opt_nowait_or_skip
 
 %type <list>	OptRoleList AlterOptRoleList
@@ -9805,11 +9806,12 @@ UnlistenStmt:
  *****************************************************************************/
 
 TransactionStmt:
-			ABORT_P opt_transaction
+			ABORT_P opt_transaction opt_transaction_chain
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
 					n->kind = TRANS_STMT_ROLLBACK;
 					n->options = NIL;
+					n->chain = $3;
 					$$ = (Node *)n;
 				}
 			| BEGIN_P opt_transaction transaction_mode_list_or_empty
@@ -9826,25 +9828,28 @@ TransactionStmt:
 					n->options = $3;
 					$$ = (Node *)n;
 				}
-			| COMMIT opt_transaction
+			| COMMIT opt_transaction opt_transaction_chain
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
 					n->kind = TRANS_STMT_COMMIT;
 					n->options = NIL;
+					n->chain = $3;
 					$$ = (Node *)n;
 				}
-			| END_P opt_transaction
+			| END_P opt_transaction opt_transaction_chain
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
 					n->kind = TRANS_STMT_COMMIT;
 					n->options = NIL;
+					n->chain = $3;
 					$$ = (Node *)n;
 				}
-			| ROLLBACK opt_transaction
+			| ROLLBACK opt_transaction opt_transaction_chain
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
 					n->kind = TRANS_STMT_ROLLBACK;
 					n->options = NIL;
+					n->chain = $3;
 					$$ = (Node *)n;
 				}
 			| SAVEPOINT ColId
@@ -9944,6 +9949,12 @@ transaction_mode_list_or_empty:
 					{ $$ = NIL; }
 		;
 
+opt_transaction_chain:
+			AND CHAIN		{ $$ = true; }
+			| AND NO CHAIN	{ $$ = false; }
+			| /* EMPTY */	{ $$ = false; }
+		;
+
 
 /*****************************************************************************
  *
diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c
index 970c94ee80..cd5c536563 100644
--- a/src/backend/tcop/utility.c
+++ b/src/backend/tcop/utility.c
@@ -440,7 +440,7 @@ standard_ProcessUtility(PlannedStmt *pstmt,
 						break;
 
 					case TRANS_STMT_COMMIT:
-						if (!EndTransactionBlock())
+						if (!EndTransactionBlock(stmt->chain))
 						{
 							/* report unsuccessful commit in completionTag */
 							if (completionTag)
@@ -471,7 +471,7 @@ standard_ProcessUtility(PlannedStmt *pstmt,
 						break;
 
 					case TRANS_STMT_ROLLBACK:
-						UserAbortTransactionBlock();
+						UserAbortTransactionBlock(stmt->chain);
 						break;
 
 					case TRANS_STMT_SAVEPOINT:
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 91df96e796..1736bdcc2d 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2077,16 +2077,18 @@ psql_completion(const char *text, int start, int end)
 		COMPLETE_WITH("WORK", "TRANSACTION", "ISOLATION LEVEL", "READ", "DEFERRABLE", "NOT DEFERRABLE");
 /* END, ABORT */
 	else if (Matches("END|ABORT"))
-		COMPLETE_WITH("WORK", "TRANSACTION");
+		COMPLETE_WITH("AND", "WORK", "TRANSACTION");
 /* COMMIT */
 	else if (Matches("COMMIT"))
-		COMPLETE_WITH("WORK", "TRANSACTION", "PREPARED");
+		COMPLETE_WITH("AND", "WORK", "TRANSACTION", "PREPARED");
 /* RELEASE SAVEPOINT */
 	else if (Matches("RELEASE"))
 		COMPLETE_WITH("SAVEPOINT");
 /* ROLLBACK */
 	else if (Matches("ROLLBACK"))
-		COMPLETE_WITH("WORK", "TRANSACTION", "TO SAVEPOINT", "PREPARED");
+		COMPLETE_WITH("AND", "WORK", "TRANSACTION", "TO SAVEPOINT", "PREPARED");
+	else if (Matches("ABORT|END|COMMIT|ROLLBACK", "AND"))
+		COMPLETE_WITH("CHAIN");
 /* CALL */
 	else if (Matches("CALL"))
 		COMPLETE_WITH_VERSIONED_SCHEMA_QUERY(Query_for_list_of_procedures, NULL);
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 689c57c592..c757146e4d 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -372,9 +372,9 @@ extern void StartTransactionCommand(void);
 extern void CommitTransactionCommand(void);
 extern void AbortCurrentTransaction(void);
 extern void BeginTransactionBlock(void);
-extern bool EndTransactionBlock(void);
+extern bool EndTransactionBlock(bool chain);
 extern bool PrepareTransactionBlock(const char *gid);
-extern void UserAbortTransactionBlock(void);
+extern void UserAbortTransactionBlock(bool chain);
 extern void BeginImplicitTransactionBlock(void);
 extern void EndImplicitTransactionBlock(void);
 extern void ReleaseSavepoint(const char *name);
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index d3dd3d0339..4010995514 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2985,6 +2985,7 @@ typedef struct TransactionStmt
 	List	   *options;		/* for BEGIN/START commands */
 	char	   *savepoint_name; /* for savepoint commands */
 	char	   *gid;			/* for two-phase-commit related commands */
+	bool		chain;			/* AND CHAIN option */
 } TransactionStmt;
 
 /* ----------------------
diff --git a/src/test/regress/expected/transactions.out b/src/test/regress/expected/transactions.out
index 69e176c525..1b316cc9b8 100644
--- a/src/test/regress/expected/transactions.out
+++ b/src/test/regress/expected/transactions.out
@@ -659,6 +659,197 @@ ERROR:  portal "ctt" cannot be run
 COMMIT;
 DROP FUNCTION create_temp_tab();
 DROP FUNCTION invert(x float8);
+-- Tests for AND CHAIN
+CREATE TABLE abc (a int);
+-- set nondefault value so we have something to override below
+SET default_transaction_read_only = on;
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ, READ WRITE, DEFERRABLE;
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ on
+(1 row)
+
+INSERT INTO abc VALUES (1);
+INSERT INTO abc VALUES (2);
+COMMIT AND CHAIN;  -- TBLOCK_END
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ on
+(1 row)
+
+INSERT INTO abc VALUES ('error');
+ERROR:  invalid input syntax for type integer: "error"
+LINE 1: INSERT INTO abc VALUES ('error');
+                                ^
+INSERT INTO abc VALUES (3);  -- check it's really aborted
+ERROR:  current transaction is aborted, commands ignored until end of transaction block
+COMMIT AND CHAIN;  -- TBLOCK_ABORT_END
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ on
+(1 row)
+
+INSERT INTO abc VALUES (4);
+COMMIT;
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ, READ WRITE, DEFERRABLE;
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ on
+(1 row)
+
+SAVEPOINT x;
+INSERT INTO abc VALUES ('error');
+ERROR:  invalid input syntax for type integer: "error"
+LINE 1: INSERT INTO abc VALUES ('error');
+                                ^
+COMMIT AND CHAIN;  -- TBLOCK_ABORT_PENDING
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ on
+(1 row)
+
+INSERT INTO abc VALUES (5);
+COMMIT;
+-- different mix of options just for fun
+START TRANSACTION ISOLATION LEVEL SERIALIZABLE, READ WRITE, NOT DEFERRABLE;
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ serializable
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ off
+(1 row)
+
+INSERT INTO abc VALUES (6);
+ROLLBACK AND CHAIN;  -- TBLOCK_ABORT_PENDING
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ serializable
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ off
+(1 row)
+
+INSERT INTO abc VALUES ('error');
+ERROR:  invalid input syntax for type integer: "error"
+LINE 1: INSERT INTO abc VALUES ('error');
+                                ^
+ROLLBACK AND CHAIN;  -- TBLOCK_ABORT_END
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ serializable
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ off
+(1 row)
+
+ROLLBACK;
+SELECT * FROM abc ORDER BY 1;
+ a 
+---
+ 1
+ 2
+ 4
+ 5
+(4 rows)
+
+RESET default_transaction_read_only;
+DROP TABLE abc;
 -- Test assorted behaviors around the implicit transaction block created
 -- when multiple SQL commands are sent in a single Query message.  These
 -- tests rely on the fact that psql will not break SQL commands apart at a
diff --git a/src/test/regress/sql/transactions.sql b/src/test/regress/sql/transactions.sql
index 2e3739fd6c..812e40a1a3 100644
--- a/src/test/regress/sql/transactions.sql
+++ b/src/test/regress/sql/transactions.sql
@@ -419,6 +419,69 @@ CREATE FUNCTION create_temp_tab() RETURNS text
 DROP FUNCTION invert(x float8);
 
 
+-- Tests for AND CHAIN
+
+CREATE TABLE abc (a int);
+
+-- set nondefault value so we have something to override below
+SET default_transaction_read_only = on;
+
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ, READ WRITE, DEFERRABLE;
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES (1);
+INSERT INTO abc VALUES (2);
+COMMIT AND CHAIN;  -- TBLOCK_END
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES ('error');
+INSERT INTO abc VALUES (3);  -- check it's really aborted
+COMMIT AND CHAIN;  -- TBLOCK_ABORT_END
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES (4);
+COMMIT;
+
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ, READ WRITE, DEFERRABLE;
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+SAVEPOINT x;
+INSERT INTO abc VALUES ('error');
+COMMIT AND CHAIN;  -- TBLOCK_ABORT_PENDING
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES (5);
+COMMIT;
+
+-- different mix of options just for fun
+START TRANSACTION ISOLATION LEVEL SERIALIZABLE, READ WRITE, NOT DEFERRABLE;
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES (6);
+ROLLBACK AND CHAIN;  -- TBLOCK_ABORT_PENDING
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES ('error');
+ROLLBACK AND CHAIN;  -- TBLOCK_ABORT_END
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+ROLLBACK;
+
+SELECT * FROM abc ORDER BY 1;
+
+RESET default_transaction_read_only;
+
+DROP TABLE abc;
+
+
 -- Test assorted behaviors around the implicit transaction block created
 -- when multiple SQL commands are sent in a single Query message.  These
 -- tests rely on the fact that psql will not break SQL commands apart at a

base-commit: 1707a0d2aa6b2bcfe78f63836c769943a1a6b9e0
-- 
2.20.1

From 0ee636cc22e27370eeb380a7de737e03f5c6521c Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 2 Jan 2019 15:09:11 +0100
Subject: [PATCH v4 2/2] Transaction chaining support in PL/pgSQL

---
 doc/src/sgml/plpgsql.sgml                     |  9 ++++++
 doc/src/sgml/spi.sgml                         | 14 +++++++---
 src/backend/access/transam/xact.c             |  4 +--
 src/backend/executor/spi.c                    | 24 ++++++++++++++--
 src/include/access/xact.h                     |  2 ++
 src/include/executor/spi.h                    |  4 +--
 src/pl/plperl/plperl.c                        |  4 +--
 .../src/expected/plpgsql_transaction.out      | 28 +++++++++++++++++++
 src/pl/plpgsql/src/pl_exec.c                  | 10 ++++---
 src/pl/plpgsql/src/pl_funcs.c                 | 10 +++++--
 src/pl/plpgsql/src/pl_gram.y                  | 18 ++++++++++--
 src/pl/plpgsql/src/pl_scanner.c               |  2 ++
 src/pl/plpgsql/src/plpgsql.h                  |  2 ++
 .../plpgsql/src/sql/plpgsql_transaction.sql   | 23 +++++++++++++++
 src/pl/plpython/plpy_plpymodule.c             |  4 +--
 src/pl/tcl/pltcl.c                            |  4 +--
 16 files changed, 138 insertions(+), 24 deletions(-)

diff --git a/doc/src/sgml/plpgsql.sgml b/doc/src/sgml/plpgsql.sgml
index 1f2abbb5d1..953c1246be 100644
--- a/doc/src/sgml/plpgsql.sgml
+++ b/doc/src/sgml/plpgsql.sgml
@@ -3490,6 +3490,15 @@ <title>Transaction Management</title>
 </programlisting>
    </para>
 
+   <para>
+    A new transaction starts out with default transaction characteristics such
+    as transaction isolation level.  In cases where transactions are committed
+    in a loop, it might be desirable to start new transactions automatically
+    with the same characteristics as the previous one.  The commands
+    <command>COMMIT AND CHAIN</command> and <command>ROLLBACK AND
+    CHAIN</command> accomplish this.
+   </para>
+
    <para>
     Transaction control is only possible in <command>CALL</command> or
     <command>DO</command> invocations from the top level or nested
diff --git a/doc/src/sgml/spi.sgml b/doc/src/sgml/spi.sgml
index 6f4f3bae6f..108c7624a8 100644
--- a/doc/src/sgml/spi.sgml
+++ b/doc/src/sgml/spi.sgml
@@ -4389,7 +4389,7 @@ <title>Transaction Management</title>
 
  <refsynopsisdiv>
 <synopsis>
-void SPI_commit(void)
+void SPI_commit(bool <parameter>chain</parameter>)
 </synopsis>
  </refsynopsisdiv>
 
@@ -4402,7 +4402,10 @@ <title>Description</title>
    command <command>COMMIT</command>.  After a transaction is committed, a new
    transaction has to be started
    using <function>SPI_start_transaction</function> before further database
-   actions can be executed.
+   actions can be executed.  If <parameter>chain</parameter> is true, then a
+   new transaction is immediately started with the same transaction
+   characteristics as the just finished one, like with the SQL command
+   <command>COMMIT AND CHAIN</command>.
   </para>
 
   <para>
@@ -4429,7 +4432,7 @@ <title>Description</title>
 
  <refsynopsisdiv>
 <synopsis>
-void SPI_rollback(void)
+void SPI_rollback(bool <parameter>chain</parameter>)
 </synopsis>
  </refsynopsisdiv>
 
@@ -4442,7 +4445,10 @@ <title>Description</title>
    command <command>ROLLBACK</command>.  After a transaction is rolled back, a
    new transaction has to be started
    using <function>SPI_start_transaction</function> before further database
-   actions can be executed.
+   actions can be executed.  If <parameter>chain</parameter> is true, then a
+   new transaction is immediately started with the same transaction
+   characteristics as the just finished one, like with the SQL command
+   <command>COMMIT AND CHAIN</command>.
   </para>
 
   <para>
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6af149d788..e8c2db3c2d 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -2774,7 +2774,7 @@ static int	save_XactIsoLevel;
 static bool	save_XactReadOnly;
 static bool	save_XactDeferrable;
 
-static void
+void
 SaveTransactionCharacteristics(void)
 {
 	save_XactIsoLevel = XactIsoLevel;
@@ -2782,7 +2782,7 @@ SaveTransactionCharacteristics(void)
 	save_XactDeferrable = XactDeferrable;
 }
 
-static void
+void
 RestoreTransactionCharacteristics(void)
 {
 	XactIsoLevel = save_XactIsoLevel;
diff --git a/src/backend/executor/spi.c b/src/backend/executor/spi.c
index ad726676d8..d61a56e095 100644
--- a/src/backend/executor/spi.c
+++ b/src/backend/executor/spi.c
@@ -218,7 +218,7 @@ SPI_start_transaction(void)
 }
 
 void
-SPI_commit(void)
+SPI_commit(bool chain)
 {
 	MemoryContext oldcontext = CurrentMemoryContext;
 
@@ -250,14 +250,24 @@ SPI_commit(void)
 	while (ActiveSnapshotSet())
 		PopActiveSnapshot();
 
+	if (chain)
+		SaveTransactionCharacteristics();
+
 	CommitTransactionCommand();
+
+	if (chain)
+	{
+		StartTransactionCommand();
+		RestoreTransactionCharacteristics();
+	}
+
 	MemoryContextSwitchTo(oldcontext);
 
 	_SPI_current->internal_xact = false;
 }
 
 void
-SPI_rollback(void)
+SPI_rollback(bool chain)
 {
 	MemoryContext oldcontext = CurrentMemoryContext;
 
@@ -274,7 +284,17 @@ SPI_rollback(void)
 
 	_SPI_current->internal_xact = true;
 
+	if (chain)
+		SaveTransactionCharacteristics();
+
 	AbortCurrentTransaction();
+
+	if (chain)
+	{
+		StartTransactionCommand();
+		RestoreTransactionCharacteristics();
+	}
+
 	MemoryContextSwitchTo(oldcontext);
 
 	_SPI_current->internal_xact = false;
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index c757146e4d..2abdbece6c 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -369,6 +369,8 @@ extern bool TransactionIdIsCurrentTransactionId(TransactionId xid);
 extern void CommandCounterIncrement(void);
 extern void ForceSyncCommit(void);
 extern void StartTransactionCommand(void);
+extern void SaveTransactionCharacteristics(void);
+extern void RestoreTransactionCharacteristics(void);
 extern void CommitTransactionCommand(void);
 extern void AbortCurrentTransaction(void);
 extern void BeginTransactionBlock(void);
diff --git a/src/include/executor/spi.h b/src/include/executor/spi.h
index d2616968ac..6bf2acb3b5 100644
--- a/src/include/executor/spi.h
+++ b/src/include/executor/spi.h
@@ -159,8 +159,8 @@ extern int	SPI_unregister_relation(const char *name);
 extern int	SPI_register_trigger_data(TriggerData *tdata);
 
 extern void SPI_start_transaction(void);
-extern void SPI_commit(void);
-extern void SPI_rollback(void);
+extern void SPI_commit(bool chain);
+extern void SPI_rollback(bool chain);
 
 extern void SPICleanup(void);
 extern void AtEOXact_SPI(bool isCommit);
diff --git a/src/pl/plperl/plperl.c b/src/pl/plperl/plperl.c
index fe54b20903..93190d1099 100644
--- a/src/pl/plperl/plperl.c
+++ b/src/pl/plperl/plperl.c
@@ -3968,7 +3968,7 @@ plperl_spi_commit(void)
 	{
 		HoldPinnedPortals();
 
-		SPI_commit();
+		SPI_commit(false);
 		SPI_start_transaction();
 	}
 	PG_CATCH();
@@ -3995,7 +3995,7 @@ plperl_spi_rollback(void)
 	{
 		HoldPinnedPortals();
 
-		SPI_rollback();
+		SPI_rollback(false);
 		SPI_start_transaction();
 	}
 	PG_CATCH();
diff --git a/src/pl/plpgsql/src/expected/plpgsql_transaction.out b/src/pl/plpgsql/src/expected/plpgsql_transaction.out
index 6eedb215a4..ba0745326a 100644
--- a/src/pl/plpgsql/src/expected/plpgsql_transaction.out
+++ b/src/pl/plpgsql/src/expected/plpgsql_transaction.out
@@ -523,6 +523,34 @@ BEGIN
 END;
 $$;
 CALL transaction_test11();
+-- transaction chain
+TRUNCATE test1;
+DO LANGUAGE plpgsql $$
+BEGIN
+    ROLLBACK;
+    SET TRANSACTION ISOLATION LEVEL REPEATABLE READ;
+    FOR i IN 0..3 LOOP
+        RAISE INFO 'transaction_isolation = %', current_setting('transaction_isolation');
+        INSERT INTO test1 (a) VALUES (i);
+        IF i % 2 = 0 THEN
+            COMMIT AND CHAIN;
+        ELSE
+            ROLLBACK AND CHAIN;
+        END IF;
+    END LOOP;
+END
+$$;
+INFO:  transaction_isolation = repeatable read
+INFO:  transaction_isolation = repeatable read
+INFO:  transaction_isolation = repeatable read
+INFO:  transaction_isolation = repeatable read
+SELECT * FROM test1;
+ a | b 
+---+---
+ 0 | 
+ 2 | 
+(2 rows)
+
 DROP TABLE test1;
 DROP TABLE test2;
 DROP TABLE test3;
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index f292fcad2d..0d8d08d6d8 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -4774,8 +4774,9 @@ exec_stmt_commit(PLpgSQL_execstate *estate, PLpgSQL_stmt_commit *stmt)
 {
 	HoldPinnedPortals();
 
-	SPI_commit();
-	SPI_start_transaction();
+	SPI_commit(stmt->chain);
+	if (!stmt->chain)
+		SPI_start_transaction();
 
 	estate->simple_eval_estate = NULL;
 	plpgsql_create_econtext(estate);
@@ -4793,8 +4794,9 @@ exec_stmt_rollback(PLpgSQL_execstate *estate, PLpgSQL_stmt_rollback *stmt)
 {
 	HoldPinnedPortals();
 
-	SPI_rollback();
-	SPI_start_transaction();
+	SPI_rollback(stmt->chain);
+	if (!stmt->chain)
+		SPI_start_transaction();
 
 	estate->simple_eval_estate = NULL;
 	plpgsql_create_econtext(estate);
diff --git a/src/pl/plpgsql/src/pl_funcs.c b/src/pl/plpgsql/src/pl_funcs.c
index 4266e6cee7..0b0f892e2d 100644
--- a/src/pl/plpgsql/src/pl_funcs.c
+++ b/src/pl/plpgsql/src/pl_funcs.c
@@ -1318,14 +1318,20 @@ static void
 dump_commit(PLpgSQL_stmt_commit *stmt)
 {
 	dump_ind();
-	printf("COMMIT\n");
+	if (stmt->chain)
+		printf("COMMIT AND CHAIN\n");
+	else
+		printf("COMMIT\n");
 }
 
 static void
 dump_rollback(PLpgSQL_stmt_rollback *stmt)
 {
 	dump_ind();
-	printf("ROLLBACK\n");
+	if (stmt->chain)
+		printf("ROLLBACK AND CHAIN\n");
+	else
+		printf("ROLLBACK\n");
 }
 
 static void
diff --git a/src/pl/plpgsql/src/pl_gram.y b/src/pl/plpgsql/src/pl_gram.y
index a979a5109d..924fbeb263 100644
--- a/src/pl/plpgsql/src/pl_gram.y
+++ b/src/pl/plpgsql/src/pl_gram.y
@@ -219,6 +219,8 @@ static	void			check_raise_parameters(PLpgSQL_stmt_raise *stmt);
 %type <ival>	opt_scrollable
 %type <fetch>	opt_fetch_direction
 
+%type <ival>	opt_transaction_chain
+
 %type <keyword>	unreserved_keyword
 
 
@@ -252,6 +254,7 @@ static	void			check_raise_parameters(PLpgSQL_stmt_raise *stmt);
 %token <keyword>	K_ABSOLUTE
 %token <keyword>	K_ALIAS
 %token <keyword>	K_ALL
+%token <keyword>	K_AND
 %token <keyword>	K_ARRAY
 %token <keyword>	K_ASSERT
 %token <keyword>	K_BACKWARD
@@ -259,6 +262,7 @@ static	void			check_raise_parameters(PLpgSQL_stmt_raise *stmt);
 %token <keyword>	K_BY
 %token <keyword>	K_CALL
 %token <keyword>	K_CASE
+%token <keyword>	K_CHAIN
 %token <keyword>	K_CLOSE
 %token <keyword>	K_COLLATE
 %token <keyword>	K_COLUMN
@@ -2177,30 +2181,38 @@ stmt_null		: K_NULL ';'
 					}
 				;
 
-stmt_commit		: K_COMMIT ';'
+stmt_commit		: K_COMMIT opt_transaction_chain ';'
 					{
 						PLpgSQL_stmt_commit *new;
 
 						new = palloc(sizeof(PLpgSQL_stmt_commit));
 						new->cmd_type = PLPGSQL_STMT_COMMIT;
 						new->lineno = plpgsql_location_to_lineno(@1);
+						new->chain = $2;
 
 						$$ = (PLpgSQL_stmt *)new;
 					}
 				;
 
-stmt_rollback	: K_ROLLBACK ';'
+stmt_rollback	: K_ROLLBACK opt_transaction_chain ';'
 					{
 						PLpgSQL_stmt_rollback *new;
 
 						new = palloc(sizeof(PLpgSQL_stmt_rollback));
 						new->cmd_type = PLPGSQL_STMT_ROLLBACK;
 						new->lineno = plpgsql_location_to_lineno(@1);
+						new->chain = $2;
 
 						$$ = (PLpgSQL_stmt *)new;
 					}
 				;
 
+opt_transaction_chain:
+			K_AND K_CHAIN			{ $$ = true; }
+			| K_AND K_NO K_CHAIN	{ $$ = false; }
+			| /* EMPTY */			{ $$ = false; }
+				;
+
 stmt_set	: K_SET
 					{
 						PLpgSQL_stmt_set *new;
@@ -2455,10 +2467,12 @@ any_identifier	: T_WORD
 unreserved_keyword	:
 				K_ABSOLUTE
 				| K_ALIAS
+				| K_AND
 				| K_ARRAY
 				| K_ASSERT
 				| K_BACKWARD
 				| K_CALL
+				| K_CHAIN
 				| K_CLOSE
 				| K_COLLATE
 				| K_COLUMN
diff --git a/src/pl/plpgsql/src/pl_scanner.c b/src/pl/plpgsql/src/pl_scanner.c
index ab18946847..d4000bcaaa 100644
--- a/src/pl/plpgsql/src/pl_scanner.c
+++ b/src/pl/plpgsql/src/pl_scanner.c
@@ -99,10 +99,12 @@ static const int num_reserved_keywords = lengthof(reserved_keywords);
 static const ScanKeyword unreserved_keywords[] = {
 	PG_KEYWORD("absolute", K_ABSOLUTE, UNRESERVED_KEYWORD)
 	PG_KEYWORD("alias", K_ALIAS, UNRESERVED_KEYWORD)
+	PG_KEYWORD("and", K_AND, UNRESERVED_KEYWORD)
 	PG_KEYWORD("array", K_ARRAY, UNRESERVED_KEYWORD)
 	PG_KEYWORD("assert", K_ASSERT, UNRESERVED_KEYWORD)
 	PG_KEYWORD("backward", K_BACKWARD, UNRESERVED_KEYWORD)
 	PG_KEYWORD("call", K_CALL, UNRESERVED_KEYWORD)
+	PG_KEYWORD("chain", K_CHAIN, UNRESERVED_KEYWORD)
 	PG_KEYWORD("close", K_CLOSE, UNRESERVED_KEYWORD)
 	PG_KEYWORD("collate", K_COLLATE, UNRESERVED_KEYWORD)
 	PG_KEYWORD("column", K_COLUMN, UNRESERVED_KEYWORD)
diff --git a/src/pl/plpgsql/src/plpgsql.h b/src/pl/plpgsql/src/plpgsql.h
index 42177ccaa6..cac14e87d8 100644
--- a/src/pl/plpgsql/src/plpgsql.h
+++ b/src/pl/plpgsql/src/plpgsql.h
@@ -533,6 +533,7 @@ typedef struct PLpgSQL_stmt_commit
 {
 	PLpgSQL_stmt_type cmd_type;
 	int			lineno;
+	bool		chain;
 } PLpgSQL_stmt_commit;
 
 /*
@@ -542,6 +543,7 @@ typedef struct PLpgSQL_stmt_rollback
 {
 	PLpgSQL_stmt_type cmd_type;
 	int			lineno;
+	bool		chain;
 } PLpgSQL_stmt_rollback;
 
 /*
diff --git a/src/pl/plpgsql/src/sql/plpgsql_transaction.sql b/src/pl/plpgsql/src/sql/plpgsql_transaction.sql
index ac1361a8ce..0c137dd31d 100644
--- a/src/pl/plpgsql/src/sql/plpgsql_transaction.sql
+++ b/src/pl/plpgsql/src/sql/plpgsql_transaction.sql
@@ -445,6 +445,29 @@ CREATE PROCEDURE transaction_test11()
 CALL transaction_test11();
 
 
+-- transaction chain
+
+TRUNCATE test1;
+
+DO LANGUAGE plpgsql $$
+BEGIN
+    ROLLBACK;
+    SET TRANSACTION ISOLATION LEVEL REPEATABLE READ;
+    FOR i IN 0..3 LOOP
+        RAISE INFO 'transaction_isolation = %', current_setting('transaction_isolation');
+        INSERT INTO test1 (a) VALUES (i);
+        IF i % 2 = 0 THEN
+            COMMIT AND CHAIN;
+        ELSE
+            ROLLBACK AND CHAIN;
+        END IF;
+    END LOOP;
+END
+$$;
+
+SELECT * FROM test1;
+
+
 DROP TABLE test1;
 DROP TABLE test2;
 DROP TABLE test3;
diff --git a/src/pl/plpython/plpy_plpymodule.c b/src/pl/plpython/plpy_plpymodule.c
index 23e49e4b75..729f402ea1 100644
--- a/src/pl/plpython/plpy_plpymodule.c
+++ b/src/pl/plpython/plpy_plpymodule.c
@@ -590,7 +590,7 @@ PLy_commit(PyObject *self, PyObject *args)
 
 	HoldPinnedPortals();
 
-	SPI_commit();
+	SPI_commit(false);
 	SPI_start_transaction();
 
 	/* was cleared at transaction end, reset pointer */
@@ -606,7 +606,7 @@ PLy_rollback(PyObject *self, PyObject *args)
 
 	HoldPinnedPortals();
 
-	SPI_rollback();
+	SPI_rollback(false);
 	SPI_start_transaction();
 
 	/* was cleared at transaction end, reset pointer */
diff --git a/src/pl/tcl/pltcl.c b/src/pl/tcl/pltcl.c
index 3b1454f833..27fa0fa53a 100644
--- a/src/pl/tcl/pltcl.c
+++ b/src/pl/tcl/pltcl.c
@@ -2931,7 +2931,7 @@ pltcl_commit(ClientData cdata, Tcl_Interp *interp,
 
 	PG_TRY();
 	{
-		SPI_commit();
+		SPI_commit(false);
 		SPI_start_transaction();
 	}
 	PG_CATCH();
@@ -2971,7 +2971,7 @@ pltcl_rollback(ClientData cdata, Tcl_Interp *interp,
 
 	PG_TRY();
 	{
-		SPI_rollback();
+		SPI_rollback(false);
 		SPI_start_transaction();
 	}
 	PG_CATCH();
-- 
2.20.1

From 87a1c30fedddeb83f7a84a0c8f7d012a0df43814 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Mon, 18 Mar 2019 10:52:12 +0100
Subject: [PATCH v5] Transaction chaining

Add command variants COMMIT AND CHAIN and ROLLBACK AND CHAIN, which
start new transactions with the same transaction characteristics as the
just finished one, per SQL standard.

Support for transaction chaining in PL/pgSQL is also added.

Discussion: https://www.postgresql.org/message-id/flat/28536681-324b-10dc-ade8-ab46f7645a5a@2ndquadrant.com
---
 doc/src/sgml/plpgsql.sgml                     |   9 +
 doc/src/sgml/ref/abort.sgml                   |  14 +-
 doc/src/sgml/ref/commit.sgml                  |  19 +-
 doc/src/sgml/ref/end.sgml                     |  14 +-
 doc/src/sgml/ref/rollback.sgml                |  19 +-
 doc/src/sgml/spi.sgml                         |  25 ++-
 src/backend/access/transam/xact.c             |  73 ++++++-
 src/backend/catalog/sql_features.txt          |   2 +-
 src/backend/executor/spi.c                    |  50 ++++-
 src/backend/nodes/copyfuncs.c                 |   1 +
 src/backend/nodes/equalfuncs.c                |   1 +
 src/backend/parser/gram.y                     |  19 +-
 src/backend/tcop/utility.c                    |   4 +-
 src/bin/psql/tab-complete.c                   |   8 +-
 src/include/access/xact.h                     |   6 +-
 src/include/executor/spi.h                    |   2 +
 src/include/nodes/parsenodes.h                |   1 +
 .../src/expected/plpgsql_transaction.out      |  28 +++
 src/pl/plpgsql/src/pl_exec.c                  |  18 +-
 src/pl/plpgsql/src/pl_funcs.c                 |  10 +-
 src/pl/plpgsql/src/pl_gram.y                  |  18 +-
 src/pl/plpgsql/src/pl_unreserved_kwlist.h     |   2 +
 src/pl/plpgsql/src/plpgsql.h                  |   2 +
 .../plpgsql/src/sql/plpgsql_transaction.sql   |  23 +++
 src/test/regress/expected/transactions.out    | 191 ++++++++++++++++++
 src/test/regress/sql/transactions.sql         |  63 ++++++
 26 files changed, 584 insertions(+), 38 deletions(-)

diff --git a/doc/src/sgml/plpgsql.sgml b/doc/src/sgml/plpgsql.sgml
index f8c6435c50..eacd67d8b6 100644
--- a/doc/src/sgml/plpgsql.sgml
+++ b/doc/src/sgml/plpgsql.sgml
@@ -3490,6 +3490,15 @@ <title>Transaction Management</title>
 </programlisting>
    </para>
 
+   <para>
+    A new transaction starts out with default transaction characteristics such
+    as transaction isolation level.  In cases where transactions are committed
+    in a loop, it might be desirable to start new transactions automatically
+    with the same characteristics as the previous one.  The commands
+    <command>COMMIT AND CHAIN</command> and <command>ROLLBACK AND
+    CHAIN</command> accomplish this.
+   </para>
+
    <para>
     Transaction control is only possible in <command>CALL</command> or
     <command>DO</command> invocations from the top level or nested
diff --git a/doc/src/sgml/ref/abort.sgml b/doc/src/sgml/ref/abort.sgml
index 21799d2a83..0372913365 100644
--- a/doc/src/sgml/ref/abort.sgml
+++ b/doc/src/sgml/ref/abort.sgml
@@ -21,7 +21,7 @@
 
  <refsynopsisdiv>
 <synopsis>
-ABORT [ WORK | TRANSACTION ]
+ABORT [ WORK | TRANSACTION ] [ AND [ NO ] CHAIN ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -51,6 +51,18 @@ <title>Parameters</title>
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term><literal>AND CHAIN</literal></term>
+    <listitem>
+     <para>
+      If <literal>AND CHAIN</literal> is specified, a new transaction is
+      immediately started with the same transaction characteristics (see <xref
+      linkend="sql-set-transaction"/>) as the just finished one.  Otherwise,
+      no new transaction is started.
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
  </refsect1>
 
diff --git a/doc/src/sgml/ref/commit.sgml b/doc/src/sgml/ref/commit.sgml
index b2e8d5d180..96a018e6aa 100644
--- a/doc/src/sgml/ref/commit.sgml
+++ b/doc/src/sgml/ref/commit.sgml
@@ -21,7 +21,7 @@
 
  <refsynopsisdiv>
 <synopsis>
-COMMIT [ WORK | TRANSACTION ]
+COMMIT [ WORK | TRANSACTION ] [ AND [ NO ] CHAIN ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -48,6 +48,18 @@ <title>Parameters</title>
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term><literal>AND CHAIN</literal></term>
+    <listitem>
+     <para>
+      If <literal>AND CHAIN</literal> is specified, a new transaction is
+      immediately started with the same transaction characteristics (see <xref
+      linkend="sql-set-transaction"/>) as the just finished one.  Otherwise,
+      no new transaction is started.
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
  </refsect1>
 
@@ -79,9 +91,8 @@ <title>Examples</title>
   <title>Compatibility</title>
 
   <para>
-   The SQL standard only specifies the two forms
-   <literal>COMMIT</literal> and <literal>COMMIT
-   WORK</literal>. Otherwise, this command is fully conforming.
+   The command <command>COMMIT</command> conforms to the SQL standard.  The
+   form <literal>COMMIT TRANSACTION</literal> is a PostgreSQL extension.
   </para>
  </refsect1>
 
diff --git a/doc/src/sgml/ref/end.sgml b/doc/src/sgml/ref/end.sgml
index 7523315f34..8b8f4f0dbb 100644
--- a/doc/src/sgml/ref/end.sgml
+++ b/doc/src/sgml/ref/end.sgml
@@ -21,7 +21,7 @@
 
  <refsynopsisdiv>
 <synopsis>
-END [ WORK | TRANSACTION ]
+END [ WORK | TRANSACTION ] [ AND [ NO ] CHAIN ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -50,6 +50,18 @@ <title>Parameters</title>
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term><literal>AND CHAIN</literal></term>
+    <listitem>
+     <para>
+      If <literal>AND CHAIN</literal> is specified, a new transaction is
+      immediately started with the same transaction characteristics (see <xref
+      linkend="sql-set-transaction"/>) as the just finished one.  Otherwise,
+      no new transaction is started.
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
  </refsect1>
 
diff --git a/doc/src/sgml/ref/rollback.sgml b/doc/src/sgml/ref/rollback.sgml
index 3cafb848a9..54fffefe18 100644
--- a/doc/src/sgml/ref/rollback.sgml
+++ b/doc/src/sgml/ref/rollback.sgml
@@ -21,7 +21,7 @@
 
  <refsynopsisdiv>
 <synopsis>
-ROLLBACK [ WORK | TRANSACTION ]
+ROLLBACK [ WORK | TRANSACTION ] [ AND [ NO ] CHAIN ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -47,6 +47,18 @@ <title>Parameters</title>
      </para>
     </listitem>
    </varlistentry>
+
+   <varlistentry>
+    <term><literal>AND CHAIN</literal></term>
+    <listitem>
+     <para>
+      If <literal>AND CHAIN</literal> is specified, a new transaction is
+      immediately started with the same transaction characteristics (see <xref
+      linkend="sql-set-transaction"/>) as the just finished one.  Otherwise,
+      no new transaction is started.
+     </para>
+    </listitem>
+   </varlistentry>
   </variablelist>
  </refsect1>
 
@@ -78,9 +90,8 @@ <title>Examples</title>
   <title>Compatibility</title>
 
   <para>
-   The SQL standard only specifies the two forms
-   <literal>ROLLBACK</literal> and <literal>ROLLBACK
-   WORK</literal>. Otherwise, this command is fully conforming.
+   The command <command>ROLLBACK</command> conforms to the SQL standard.  The
+   form <literal>ROLLBACK TRANSACTION</literal> is a PostgreSQL extension.
   </para>
  </refsect1>
 
diff --git a/doc/src/sgml/spi.sgml b/doc/src/sgml/spi.sgml
index 6f4f3bae6f..8ed4814d9a 100644
--- a/doc/src/sgml/spi.sgml
+++ b/doc/src/sgml/spi.sgml
@@ -4390,6 +4390,10 @@ <title>Transaction Management</title>
  <refsynopsisdiv>
 <synopsis>
 void SPI_commit(void)
+</synopsis>
+
+<synopsis>
+void SPI_commit_and_chain(void)
 </synopsis>
  </refsynopsisdiv>
 
@@ -4406,7 +4410,14 @@ <title>Description</title>
   </para>
 
   <para>
-   This function can only be executed if the SPI connection has been set as
+   <function>SPI_commit_and_chain</function> is the same, but a new
+   transaction is immediately started with the same transaction
+   characteristics as the just finished one, like with the SQL command
+   <command>COMMIT AND CHAIN</command>.
+  </para>
+
+  <para>
+   These functions can only be executed if the SPI connection has been set as
    nonatomic in the call to <function>SPI_connect_ext</function>.
   </para>
  </refsect1>
@@ -4430,6 +4441,10 @@ <title>Description</title>
  <refsynopsisdiv>
 <synopsis>
 void SPI_rollback(void)
+</synopsis>
+
+<synopsis>
+void SPI_rollback_and_chain(void)
 </synopsis>
  </refsynopsisdiv>
 
@@ -4444,9 +4459,15 @@ <title>Description</title>
    using <function>SPI_start_transaction</function> before further database
    actions can be executed.
   </para>
+  <para>
+   <function>SPI_rollback_and_chain</function> is the same, but a new
+   transaction is immediately started with the same transaction
+   characteristics as the just finished one, like with the SQL command
+   <command>ROLLBACK AND CHAIN</command>.
+  </para>
 
   <para>
-   This function can only be executed if the SPI connection has been set as
+   These functions can only be executed if the SPI connection has been set as
    nonatomic in the call to <function>SPI_connect_ext</function>.
   </para>
  </refsect1>
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 6e5891749b..c3214d4f4d 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -190,6 +190,7 @@ typedef struct TransactionStateData
 	bool		startedInRecovery;	/* did we start in recovery? */
 	bool		didLogXid;		/* has xid been included in WAL record? */
 	int			parallelModeLevel;	/* Enter/ExitParallelMode counter */
+	bool		chain;			/* start a new block after this one */
 	struct TransactionStateData *parent;	/* back link to parent */
 } TransactionStateData;
 
@@ -2775,6 +2776,36 @@ StartTransactionCommand(void)
 	MemoryContextSwitchTo(CurTransactionContext);
 }
 
+
+/*
+ * Simple system for saving and restoring transaction characteristics
+ * (isolation level, read only, deferrable).  We need this for transaction
+ * chaining, so that we can set the characteristics of the new transaction to
+ * be the same as the previous one.  (We need something like this because the
+ * GUC system resets the characteristics at transaction end, so for example
+ * just skipping the reset in StartTransaction() won't work.)
+ */
+static int	save_XactIsoLevel;
+static bool	save_XactReadOnly;
+static bool	save_XactDeferrable;
+
+void
+SaveTransactionCharacteristics(void)
+{
+	save_XactIsoLevel = XactIsoLevel;
+	save_XactReadOnly = XactReadOnly;
+	save_XactDeferrable = XactDeferrable;
+}
+
+void
+RestoreTransactionCharacteristics(void)
+{
+	XactIsoLevel = save_XactIsoLevel;
+	XactReadOnly = save_XactReadOnly;
+	XactDeferrable = save_XactDeferrable;
+}
+
+
 /*
  *	CommitTransactionCommand
  */
@@ -2783,6 +2814,9 @@ CommitTransactionCommand(void)
 {
 	TransactionState s = CurrentTransactionState;
 
+	if (s->chain)
+		SaveTransactionCharacteristics();
+
 	switch (s->blockState)
 	{
 			/*
@@ -2834,6 +2868,13 @@ CommitTransactionCommand(void)
 		case TBLOCK_END:
 			CommitTransaction();
 			s->blockState = TBLOCK_DEFAULT;
+			if (s->chain)
+			{
+				StartTransaction();
+				s->blockState = TBLOCK_INPROGRESS;
+				s->chain = false;
+				RestoreTransactionCharacteristics();
+			}
 			break;
 
 			/*
@@ -2853,6 +2894,13 @@ CommitTransactionCommand(void)
 		case TBLOCK_ABORT_END:
 			CleanupTransaction();
 			s->blockState = TBLOCK_DEFAULT;
+			if (s->chain)
+			{
+				StartTransaction();
+				s->blockState = TBLOCK_INPROGRESS;
+				s->chain = false;
+				RestoreTransactionCharacteristics();
+			}
 			break;
 
 			/*
@@ -2864,6 +2912,13 @@ CommitTransactionCommand(void)
 			AbortTransaction();
 			CleanupTransaction();
 			s->blockState = TBLOCK_DEFAULT;
+			if (s->chain)
+			{
+				StartTransaction();
+				s->blockState = TBLOCK_INPROGRESS;
+				s->chain = false;
+				RestoreTransactionCharacteristics();
+			}
 			break;
 
 			/*
@@ -3521,7 +3576,7 @@ PrepareTransactionBlock(const char *gid)
 	bool		result;
 
 	/* Set up to commit the current transaction */
-	result = EndTransactionBlock();
+	result = EndTransactionBlock(false);
 
 	/* If successful, change outer tblock state to PREPARE */
 	if (result)
@@ -3567,7 +3622,7 @@ PrepareTransactionBlock(const char *gid)
  * resource owner, etc while executing inside a Portal.
  */
 bool
-EndTransactionBlock(void)
+EndTransactionBlock(bool chain)
 {
 	TransactionState s = CurrentTransactionState;
 	bool		result = false;
@@ -3693,6 +3748,13 @@ EndTransactionBlock(void)
 			break;
 	}
 
+	Assert(s->blockState == TBLOCK_STARTED ||
+		   s->blockState == TBLOCK_END ||
+		   s->blockState == TBLOCK_ABORT_END ||
+		   s->blockState == TBLOCK_ABORT_PENDING);
+
+	s->chain = chain;
+
 	return result;
 }
 
@@ -3703,7 +3765,7 @@ EndTransactionBlock(void)
  * As above, we don't actually do anything here except change blockState.
  */
 void
-UserAbortTransactionBlock(void)
+UserAbortTransactionBlock(bool chain)
 {
 	TransactionState s = CurrentTransactionState;
 
@@ -3801,6 +3863,11 @@ UserAbortTransactionBlock(void)
 				 BlockStateAsString(s->blockState));
 			break;
 	}
+
+	Assert(s->blockState == TBLOCK_ABORT_END ||
+		   s->blockState == TBLOCK_ABORT_PENDING);
+
+	s->chain = chain;
 }
 
 /*
diff --git a/src/backend/catalog/sql_features.txt b/src/backend/catalog/sql_features.txt
index bade0fe9ae..6b23163929 100644
--- a/src/backend/catalog/sql_features.txt
+++ b/src/backend/catalog/sql_features.txt
@@ -443,7 +443,7 @@ T213	INSTEAD OF triggers			YES
 T231	Sensitive cursors			YES	
 T241	START TRANSACTION statement			YES	
 T251	SET TRANSACTION statement: LOCAL option			NO	
-T261	Chained transactions			NO	
+T261	Chained transactions			YES	
 T271	Savepoints			YES	
 T272	Enhanced savepoint management			NO	
 T281	SELECT privilege with column granularity			YES	
diff --git a/src/backend/executor/spi.c b/src/backend/executor/spi.c
index d898f4ca78..6e262d1a3a 100644
--- a/src/backend/executor/spi.c
+++ b/src/backend/executor/spi.c
@@ -217,8 +217,8 @@ SPI_start_transaction(void)
 	MemoryContextSwitchTo(oldcontext);
 }
 
-void
-SPI_commit(void)
+static void
+_SPI_commit(bool chain)
 {
 	MemoryContext oldcontext = CurrentMemoryContext;
 
@@ -250,14 +250,36 @@ SPI_commit(void)
 	while (ActiveSnapshotSet())
 		PopActiveSnapshot();
 
+	if (chain)
+		SaveTransactionCharacteristics();
+
 	CommitTransactionCommand();
+
+	if (chain)
+	{
+		StartTransactionCommand();
+		RestoreTransactionCharacteristics();
+	}
+
 	MemoryContextSwitchTo(oldcontext);
 
 	_SPI_current->internal_xact = false;
 }
 
 void
-SPI_rollback(void)
+SPI_commit(void)
+{
+	_SPI_commit(false);
+}
+
+void
+SPI_commit_and_chain(void)
+{
+	_SPI_commit(true);
+}
+
+static void
+_SPI_rollback(bool chain)
 {
 	MemoryContext oldcontext = CurrentMemoryContext;
 
@@ -274,12 +296,34 @@ SPI_rollback(void)
 
 	_SPI_current->internal_xact = true;
 
+	if (chain)
+		SaveTransactionCharacteristics();
+
 	AbortCurrentTransaction();
+
+	if (chain)
+	{
+		StartTransactionCommand();
+		RestoreTransactionCharacteristics();
+	}
+
 	MemoryContextSwitchTo(oldcontext);
 
 	_SPI_current->internal_xact = false;
 }
 
+void
+SPI_rollback(void)
+{
+	_SPI_rollback(false);
+}
+
+void
+SPI_rollback_and_chain(void)
+{
+	_SPI_rollback(true);
+}
+
 /*
  * Clean up SPI state.  Called on transaction end (of non-SPI-internal
  * transactions) and when returning to the main loop on error.
diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index a8a735c247..8a3b316fed 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -3658,6 +3658,7 @@ _copyTransactionStmt(const TransactionStmt *from)
 	COPY_NODE_FIELD(options);
 	COPY_STRING_FIELD(savepoint_name);
 	COPY_STRING_FIELD(gid);
+	COPY_SCALAR_FIELD(chain);
 
 	return newnode;
 }
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 3cab90e9f8..37f3359b94 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -1509,6 +1509,7 @@ _equalTransactionStmt(const TransactionStmt *a, const TransactionStmt *b)
 	COMPARE_NODE_FIELD(options);
 	COMPARE_STRING_FIELD(savepoint_name);
 	COMPARE_STRING_FIELD(gid);
+	COMPARE_SCALAR_FIELD(chain);
 
 	return true;
 }
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index e23e68fdb3..d6836de33f 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -311,6 +311,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 %type <boolean>	opt_or_replace
 				opt_grant_grant_option opt_grant_admin_option
 				opt_nowait opt_if_exists opt_with_data
+				opt_transaction_chain
 %type <ival>	opt_nowait_or_skip
 
 %type <list>	OptRoleList AlterOptRoleList
@@ -9789,11 +9790,12 @@ UnlistenStmt:
  *****************************************************************************/
 
 TransactionStmt:
-			ABORT_P opt_transaction
+			ABORT_P opt_transaction opt_transaction_chain
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
 					n->kind = TRANS_STMT_ROLLBACK;
 					n->options = NIL;
+					n->chain = $3;
 					$$ = (Node *)n;
 				}
 			| BEGIN_P opt_transaction transaction_mode_list_or_empty
@@ -9810,25 +9812,28 @@ TransactionStmt:
 					n->options = $3;
 					$$ = (Node *)n;
 				}
-			| COMMIT opt_transaction
+			| COMMIT opt_transaction opt_transaction_chain
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
 					n->kind = TRANS_STMT_COMMIT;
 					n->options = NIL;
+					n->chain = $3;
 					$$ = (Node *)n;
 				}
-			| END_P opt_transaction
+			| END_P opt_transaction opt_transaction_chain
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
 					n->kind = TRANS_STMT_COMMIT;
 					n->options = NIL;
+					n->chain = $3;
 					$$ = (Node *)n;
 				}
-			| ROLLBACK opt_transaction
+			| ROLLBACK opt_transaction opt_transaction_chain
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
 					n->kind = TRANS_STMT_ROLLBACK;
 					n->options = NIL;
+					n->chain = $3;
 					$$ = (Node *)n;
 				}
 			| SAVEPOINT ColId
@@ -9928,6 +9933,12 @@ transaction_mode_list_or_empty:
 					{ $$ = NIL; }
 		;
 
+opt_transaction_chain:
+			AND CHAIN		{ $$ = true; }
+			| AND NO CHAIN	{ $$ = false; }
+			| /* EMPTY */	{ $$ = false; }
+		;
+
 
 /*****************************************************************************
  *
diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c
index 6ec795f1b4..8eded2908c 100644
--- a/src/backend/tcop/utility.c
+++ b/src/backend/tcop/utility.c
@@ -440,7 +440,7 @@ standard_ProcessUtility(PlannedStmt *pstmt,
 						break;
 
 					case TRANS_STMT_COMMIT:
-						if (!EndTransactionBlock())
+						if (!EndTransactionBlock(stmt->chain))
 						{
 							/* report unsuccessful commit in completionTag */
 							if (completionTag)
@@ -471,7 +471,7 @@ standard_ProcessUtility(PlannedStmt *pstmt,
 						break;
 
 					case TRANS_STMT_ROLLBACK:
-						UserAbortTransactionBlock();
+						UserAbortTransactionBlock(stmt->chain);
 						break;
 
 					case TRANS_STMT_SAVEPOINT:
diff --git a/src/bin/psql/tab-complete.c b/src/bin/psql/tab-complete.c
index 10ae21cc61..3ba3498496 100644
--- a/src/bin/psql/tab-complete.c
+++ b/src/bin/psql/tab-complete.c
@@ -2091,16 +2091,18 @@ psql_completion(const char *text, int start, int end)
 		COMPLETE_WITH("WORK", "TRANSACTION", "ISOLATION LEVEL", "READ", "DEFERRABLE", "NOT DEFERRABLE");
 /* END, ABORT */
 	else if (Matches("END|ABORT"))
-		COMPLETE_WITH("WORK", "TRANSACTION");
+		COMPLETE_WITH("AND", "WORK", "TRANSACTION");
 /* COMMIT */
 	else if (Matches("COMMIT"))
-		COMPLETE_WITH("WORK", "TRANSACTION", "PREPARED");
+		COMPLETE_WITH("AND", "WORK", "TRANSACTION", "PREPARED");
 /* RELEASE SAVEPOINT */
 	else if (Matches("RELEASE"))
 		COMPLETE_WITH("SAVEPOINT");
 /* ROLLBACK */
 	else if (Matches("ROLLBACK"))
-		COMPLETE_WITH("WORK", "TRANSACTION", "TO SAVEPOINT", "PREPARED");
+		COMPLETE_WITH("AND", "WORK", "TRANSACTION", "TO SAVEPOINT", "PREPARED");
+	else if (Matches("ABORT|END|COMMIT|ROLLBACK", "AND"))
+		COMPLETE_WITH("CHAIN");
 /* CALL */
 	else if (Matches("CALL"))
 		COMPLETE_WITH_VERSIONED_SCHEMA_QUERY(Query_for_list_of_procedures, NULL);
diff --git a/src/include/access/xact.h b/src/include/access/xact.h
index 426e77846f..e8579dcd47 100644
--- a/src/include/access/xact.h
+++ b/src/include/access/xact.h
@@ -368,12 +368,14 @@ extern bool TransactionIdIsCurrentTransactionId(TransactionId xid);
 extern void CommandCounterIncrement(void);
 extern void ForceSyncCommit(void);
 extern void StartTransactionCommand(void);
+extern void SaveTransactionCharacteristics(void);
+extern void RestoreTransactionCharacteristics(void);
 extern void CommitTransactionCommand(void);
 extern void AbortCurrentTransaction(void);
 extern void BeginTransactionBlock(void);
-extern bool EndTransactionBlock(void);
+extern bool EndTransactionBlock(bool chain);
 extern bool PrepareTransactionBlock(const char *gid);
-extern void UserAbortTransactionBlock(void);
+extern void UserAbortTransactionBlock(bool chain);
 extern void BeginImplicitTransactionBlock(void);
 extern void EndImplicitTransactionBlock(void);
 extern void ReleaseSavepoint(const char *name);
diff --git a/src/include/executor/spi.h b/src/include/executor/spi.h
index eafcc7a4e4..83c28b79bf 100644
--- a/src/include/executor/spi.h
+++ b/src/include/executor/spi.h
@@ -160,7 +160,9 @@ extern int	SPI_register_trigger_data(TriggerData *tdata);
 
 extern void SPI_start_transaction(void);
 extern void SPI_commit(void);
+extern void SPI_commit_and_chain(void);
 extern void SPI_rollback(void);
+extern void SPI_rollback_and_chain(void);
 
 extern void SPICleanup(void);
 extern void AtEOXact_SPI(bool isCommit);
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index fe35783359..a883ff2e35 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2997,6 +2997,7 @@ typedef struct TransactionStmt
 	List	   *options;		/* for BEGIN/START commands */
 	char	   *savepoint_name; /* for savepoint commands */
 	char	   *gid;			/* for two-phase-commit related commands */
+	bool		chain;			/* AND CHAIN option */
 } TransactionStmt;
 
 /* ----------------------
diff --git a/src/pl/plpgsql/src/expected/plpgsql_transaction.out b/src/pl/plpgsql/src/expected/plpgsql_transaction.out
index 6eedb215a4..ba0745326a 100644
--- a/src/pl/plpgsql/src/expected/plpgsql_transaction.out
+++ b/src/pl/plpgsql/src/expected/plpgsql_transaction.out
@@ -523,6 +523,34 @@ BEGIN
 END;
 $$;
 CALL transaction_test11();
+-- transaction chain
+TRUNCATE test1;
+DO LANGUAGE plpgsql $$
+BEGIN
+    ROLLBACK;
+    SET TRANSACTION ISOLATION LEVEL REPEATABLE READ;
+    FOR i IN 0..3 LOOP
+        RAISE INFO 'transaction_isolation = %', current_setting('transaction_isolation');
+        INSERT INTO test1 (a) VALUES (i);
+        IF i % 2 = 0 THEN
+            COMMIT AND CHAIN;
+        ELSE
+            ROLLBACK AND CHAIN;
+        END IF;
+    END LOOP;
+END
+$$;
+INFO:  transaction_isolation = repeatable read
+INFO:  transaction_isolation = repeatable read
+INFO:  transaction_isolation = repeatable read
+INFO:  transaction_isolation = repeatable read
+SELECT * FROM test1;
+ a | b 
+---+---
+ 0 | 
+ 2 | 
+(2 rows)
+
 DROP TABLE test1;
 DROP TABLE test2;
 DROP TABLE test3;
diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index 6dfcd1611a..527cada4fe 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -4773,8 +4773,13 @@ exec_stmt_commit(PLpgSQL_execstate *estate, PLpgSQL_stmt_commit *stmt)
 {
 	HoldPinnedPortals();
 
-	SPI_commit();
-	SPI_start_transaction();
+	if (stmt->chain)
+		SPI_commit_and_chain();
+	else
+	{
+		SPI_commit();
+		SPI_start_transaction();
+	}
 
 	estate->simple_eval_estate = NULL;
 	plpgsql_create_econtext(estate);
@@ -4792,8 +4797,13 @@ exec_stmt_rollback(PLpgSQL_execstate *estate, PLpgSQL_stmt_rollback *stmt)
 {
 	HoldPinnedPortals();
 
-	SPI_rollback();
-	SPI_start_transaction();
+	if (stmt->chain)
+		SPI_rollback_and_chain();
+	else
+	{
+		SPI_rollback();
+		SPI_start_transaction();
+	}
 
 	estate->simple_eval_estate = NULL;
 	plpgsql_create_econtext(estate);
diff --git a/src/pl/plpgsql/src/pl_funcs.c b/src/pl/plpgsql/src/pl_funcs.c
index 0b63da2b4a..053f83dc74 100644
--- a/src/pl/plpgsql/src/pl_funcs.c
+++ b/src/pl/plpgsql/src/pl_funcs.c
@@ -1318,14 +1318,20 @@ static void
 dump_commit(PLpgSQL_stmt_commit *stmt)
 {
 	dump_ind();
-	printf("COMMIT\n");
+	if (stmt->chain)
+		printf("COMMIT AND CHAIN\n");
+	else
+		printf("COMMIT\n");
 }
 
 static void
 dump_rollback(PLpgSQL_stmt_rollback *stmt)
 {
 	dump_ind();
-	printf("ROLLBACK\n");
+	if (stmt->chain)
+		printf("ROLLBACK AND CHAIN\n");
+	else
+		printf("ROLLBACK\n");
 }
 
 static void
diff --git a/src/pl/plpgsql/src/pl_gram.y b/src/pl/plpgsql/src/pl_gram.y
index 03f7cdce8c..dea95f4230 100644
--- a/src/pl/plpgsql/src/pl_gram.y
+++ b/src/pl/plpgsql/src/pl_gram.y
@@ -219,6 +219,8 @@ static	void			check_raise_parameters(PLpgSQL_stmt_raise *stmt);
 %type <ival>	opt_scrollable
 %type <fetch>	opt_fetch_direction
 
+%type <ival>	opt_transaction_chain
+
 %type <keyword>	unreserved_keyword
 
 
@@ -252,6 +254,7 @@ static	void			check_raise_parameters(PLpgSQL_stmt_raise *stmt);
 %token <keyword>	K_ABSOLUTE
 %token <keyword>	K_ALIAS
 %token <keyword>	K_ALL
+%token <keyword>	K_AND
 %token <keyword>	K_ARRAY
 %token <keyword>	K_ASSERT
 %token <keyword>	K_BACKWARD
@@ -259,6 +262,7 @@ static	void			check_raise_parameters(PLpgSQL_stmt_raise *stmt);
 %token <keyword>	K_BY
 %token <keyword>	K_CALL
 %token <keyword>	K_CASE
+%token <keyword>	K_CHAIN
 %token <keyword>	K_CLOSE
 %token <keyword>	K_COLLATE
 %token <keyword>	K_COLUMN
@@ -2199,7 +2203,7 @@ stmt_null		: K_NULL ';'
 					}
 				;
 
-stmt_commit		: K_COMMIT ';'
+stmt_commit		: K_COMMIT opt_transaction_chain ';'
 					{
 						PLpgSQL_stmt_commit *new;
 
@@ -2207,12 +2211,13 @@ stmt_commit		: K_COMMIT ';'
 						new->cmd_type = PLPGSQL_STMT_COMMIT;
 						new->lineno = plpgsql_location_to_lineno(@1);
 						new->stmtid = ++plpgsql_curr_compile->nstatements;
+						new->chain = $2;
 
 						$$ = (PLpgSQL_stmt *)new;
 					}
 				;
 
-stmt_rollback	: K_ROLLBACK ';'
+stmt_rollback	: K_ROLLBACK opt_transaction_chain ';'
 					{
 						PLpgSQL_stmt_rollback *new;
 
@@ -2220,11 +2225,18 @@ stmt_rollback	: K_ROLLBACK ';'
 						new->cmd_type = PLPGSQL_STMT_ROLLBACK;
 						new->lineno = plpgsql_location_to_lineno(@1);
 						new->stmtid = ++plpgsql_curr_compile->nstatements;
+						new->chain = $2;
 
 						$$ = (PLpgSQL_stmt *)new;
 					}
 				;
 
+opt_transaction_chain:
+			K_AND K_CHAIN			{ $$ = true; }
+			| K_AND K_NO K_CHAIN	{ $$ = false; }
+			| /* EMPTY */			{ $$ = false; }
+				;
+
 stmt_set	: K_SET
 					{
 						PLpgSQL_stmt_set *new;
@@ -2482,10 +2494,12 @@ any_identifier	: T_WORD
 unreserved_keyword	:
 				K_ABSOLUTE
 				| K_ALIAS
+				| K_AND
 				| K_ARRAY
 				| K_ASSERT
 				| K_BACKWARD
 				| K_CALL
+				| K_CHAIN
 				| K_CLOSE
 				| K_COLLATE
 				| K_COLUMN
diff --git a/src/pl/plpgsql/src/pl_unreserved_kwlist.h b/src/pl/plpgsql/src/pl_unreserved_kwlist.h
index ce4be81dd8..6d85f9396e 100644
--- a/src/pl/plpgsql/src/pl_unreserved_kwlist.h
+++ b/src/pl/plpgsql/src/pl_unreserved_kwlist.h
@@ -29,10 +29,12 @@
 /* name, value */
 PG_KEYWORD("absolute", K_ABSOLUTE)
 PG_KEYWORD("alias", K_ALIAS)
+PG_KEYWORD("and", K_AND)
 PG_KEYWORD("array", K_ARRAY)
 PG_KEYWORD("assert", K_ASSERT)
 PG_KEYWORD("backward", K_BACKWARD)
 PG_KEYWORD("call", K_CALL)
+PG_KEYWORD("chain", K_CHAIN)
 PG_KEYWORD("close", K_CLOSE)
 PG_KEYWORD("collate", K_COLLATE)
 PG_KEYWORD("column", K_COLUMN)
diff --git a/src/pl/plpgsql/src/plpgsql.h b/src/pl/plpgsql/src/plpgsql.h
index 0a5fbfa9d6..4eff62e8e5 100644
--- a/src/pl/plpgsql/src/plpgsql.h
+++ b/src/pl/plpgsql/src/plpgsql.h
@@ -545,6 +545,7 @@ typedef struct PLpgSQL_stmt_commit
 	PLpgSQL_stmt_type cmd_type;
 	int			lineno;
 	unsigned int stmtid;
+	bool		chain;
 } PLpgSQL_stmt_commit;
 
 /*
@@ -555,6 +556,7 @@ typedef struct PLpgSQL_stmt_rollback
 	PLpgSQL_stmt_type cmd_type;
 	int			lineno;
 	unsigned int stmtid;
+	bool		chain;
 } PLpgSQL_stmt_rollback;
 
 /*
diff --git a/src/pl/plpgsql/src/sql/plpgsql_transaction.sql b/src/pl/plpgsql/src/sql/plpgsql_transaction.sql
index ac1361a8ce..0c137dd31d 100644
--- a/src/pl/plpgsql/src/sql/plpgsql_transaction.sql
+++ b/src/pl/plpgsql/src/sql/plpgsql_transaction.sql
@@ -445,6 +445,29 @@ CREATE PROCEDURE transaction_test11()
 CALL transaction_test11();
 
 
+-- transaction chain
+
+TRUNCATE test1;
+
+DO LANGUAGE plpgsql $$
+BEGIN
+    ROLLBACK;
+    SET TRANSACTION ISOLATION LEVEL REPEATABLE READ;
+    FOR i IN 0..3 LOOP
+        RAISE INFO 'transaction_isolation = %', current_setting('transaction_isolation');
+        INSERT INTO test1 (a) VALUES (i);
+        IF i % 2 = 0 THEN
+            COMMIT AND CHAIN;
+        ELSE
+            ROLLBACK AND CHAIN;
+        END IF;
+    END LOOP;
+END
+$$;
+
+SELECT * FROM test1;
+
+
 DROP TABLE test1;
 DROP TABLE test2;
 DROP TABLE test3;
diff --git a/src/test/regress/expected/transactions.out b/src/test/regress/expected/transactions.out
index 69e176c525..1b316cc9b8 100644
--- a/src/test/regress/expected/transactions.out
+++ b/src/test/regress/expected/transactions.out
@@ -659,6 +659,197 @@ ERROR:  portal "ctt" cannot be run
 COMMIT;
 DROP FUNCTION create_temp_tab();
 DROP FUNCTION invert(x float8);
+-- Tests for AND CHAIN
+CREATE TABLE abc (a int);
+-- set nondefault value so we have something to override below
+SET default_transaction_read_only = on;
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ, READ WRITE, DEFERRABLE;
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ on
+(1 row)
+
+INSERT INTO abc VALUES (1);
+INSERT INTO abc VALUES (2);
+COMMIT AND CHAIN;  -- TBLOCK_END
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ on
+(1 row)
+
+INSERT INTO abc VALUES ('error');
+ERROR:  invalid input syntax for type integer: "error"
+LINE 1: INSERT INTO abc VALUES ('error');
+                                ^
+INSERT INTO abc VALUES (3);  -- check it's really aborted
+ERROR:  current transaction is aborted, commands ignored until end of transaction block
+COMMIT AND CHAIN;  -- TBLOCK_ABORT_END
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ on
+(1 row)
+
+INSERT INTO abc VALUES (4);
+COMMIT;
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ, READ WRITE, DEFERRABLE;
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ on
+(1 row)
+
+SAVEPOINT x;
+INSERT INTO abc VALUES ('error');
+ERROR:  invalid input syntax for type integer: "error"
+LINE 1: INSERT INTO abc VALUES ('error');
+                                ^
+COMMIT AND CHAIN;  -- TBLOCK_ABORT_PENDING
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ repeatable read
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ on
+(1 row)
+
+INSERT INTO abc VALUES (5);
+COMMIT;
+-- different mix of options just for fun
+START TRANSACTION ISOLATION LEVEL SERIALIZABLE, READ WRITE, NOT DEFERRABLE;
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ serializable
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ off
+(1 row)
+
+INSERT INTO abc VALUES (6);
+ROLLBACK AND CHAIN;  -- TBLOCK_ABORT_PENDING
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ serializable
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ off
+(1 row)
+
+INSERT INTO abc VALUES ('error');
+ERROR:  invalid input syntax for type integer: "error"
+LINE 1: INSERT INTO abc VALUES ('error');
+                                ^
+ROLLBACK AND CHAIN;  -- TBLOCK_ABORT_END
+SHOW transaction_isolation;
+ transaction_isolation 
+-----------------------
+ serializable
+(1 row)
+
+SHOW transaction_read_only;
+ transaction_read_only 
+-----------------------
+ off
+(1 row)
+
+SHOW transaction_deferrable;
+ transaction_deferrable 
+------------------------
+ off
+(1 row)
+
+ROLLBACK;
+SELECT * FROM abc ORDER BY 1;
+ a 
+---
+ 1
+ 2
+ 4
+ 5
+(4 rows)
+
+RESET default_transaction_read_only;
+DROP TABLE abc;
 -- Test assorted behaviors around the implicit transaction block created
 -- when multiple SQL commands are sent in a single Query message.  These
 -- tests rely on the fact that psql will not break SQL commands apart at a
diff --git a/src/test/regress/sql/transactions.sql b/src/test/regress/sql/transactions.sql
index 2e3739fd6c..812e40a1a3 100644
--- a/src/test/regress/sql/transactions.sql
+++ b/src/test/regress/sql/transactions.sql
@@ -419,6 +419,69 @@ CREATE FUNCTION create_temp_tab() RETURNS text
 DROP FUNCTION invert(x float8);
 
 
+-- Tests for AND CHAIN
+
+CREATE TABLE abc (a int);
+
+-- set nondefault value so we have something to override below
+SET default_transaction_read_only = on;
+
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ, READ WRITE, DEFERRABLE;
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES (1);
+INSERT INTO abc VALUES (2);
+COMMIT AND CHAIN;  -- TBLOCK_END
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES ('error');
+INSERT INTO abc VALUES (3);  -- check it's really aborted
+COMMIT AND CHAIN;  -- TBLOCK_ABORT_END
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES (4);
+COMMIT;
+
+START TRANSACTION ISOLATION LEVEL REPEATABLE READ, READ WRITE, DEFERRABLE;
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+SAVEPOINT x;
+INSERT INTO abc VALUES ('error');
+COMMIT AND CHAIN;  -- TBLOCK_ABORT_PENDING
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES (5);
+COMMIT;
+
+-- different mix of options just for fun
+START TRANSACTION ISOLATION LEVEL SERIALIZABLE, READ WRITE, NOT DEFERRABLE;
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES (6);
+ROLLBACK AND CHAIN;  -- TBLOCK_ABORT_PENDING
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+INSERT INTO abc VALUES ('error');
+ROLLBACK AND CHAIN;  -- TBLOCK_ABORT_END
+SHOW transaction_isolation;
+SHOW transaction_read_only;
+SHOW transaction_deferrable;
+ROLLBACK;
+
+SELECT * FROM abc ORDER BY 1;
+
+RESET default_transaction_read_only;
+
+DROP TABLE abc;
+
+
 -- Test assorted behaviors around the implicit transaction block created
 -- when multiple SQL commands are sent in a single Query message.  These
 -- tests rely on the fact that psql will not break SQL commands apart at a

base-commit: a0478b69985056965a5737184279a99bde421f69
-- 
2.21.0