Transaction control in PL procedures

In each of the supplied procedural languages (PL/pgSQL, PL/Perl,
PL/Python, PL/Tcl), add language-specific commit and rollback
functions/commands to control transactions in procedures in that
language.  Add similar underlying functions to SPI.  Some additional
cleanup so that transaction commit or abort doesn't blow away data
structures still used by the procedure call.  Add execution context
tracking to CALL and DO statements so that transaction control commands
can only be issued in top-level procedure and block calls, not function
calls or other procedure or block calls.

- SPI

Add a new function SPI_connect_ext() that is like SPI_connect() but
allows passing option flags.  The only option flag right now is
SPI_OPT_NONATOMIC.  A nonatomic SPI connection can execute transaction
control commands, otherwise it's not allowed.  This is meant to be
passed down from CALL and DO statements which themselves know in which
context they are called.  A nonatomic SPI connection uses different
memory management.  A normal SPI connection allocates its memory in
TopTransactionContext.  For nonatomic connections we use PortalContext
instead.  As the comment in SPI_connect_ext() (previously SPI_connect())
indicates, one could potentially use PortalContext in all cases, but it
seems safest to leave the existing uses alone, because this stuff is
complicated enough already.

SPI also gets new functions SPI_start_transaction(), SPI_commit(), and
SPI_rollback(), which can be used by PLs to implement their transaction
control logic.

- portalmem.c

Some adjustments were made in the code that cleans up portals at
transaction abort.  The portal code could already handle a command
*committing* a transaction and continuing (e.g., VACUUM), but it was not
quite prepared for a command *aborting* a transaction and continuing.

In AtAbort_Portals(), remove the code that marks an active portal as
failed.  As the comment there already predicted, this doesn't work if
the running command wants to keep running after transaction abort.  And
it's actually not necessary, because pquery.c is careful to run all
portal code in a PG_TRY block and explicitly runs MarkPortalFailed() if
there is an exception.  So the code in AtAbort_Portals() is never used
anyway.

In AtAbort_Portals() and AtCleanup_Portals(), we need to be careful not
to clean up active portals too much.  This mirrors similar code in
PreCommit_Portals().

- PL/Perl

Gets new functions spi_commit() and spi_rollback()

- PL/pgSQL

Gets new commands COMMIT and ROLLBACK.

Update the PL/SQL porting example in the documentation to reflect that
transactions are now possible in procedures.

- PL/Python

Gets new functions plpy.commit and plpy.rollback.

- PL/Tcl

Gets new commands commit and rollback.

Reviewed-by: Andrew Dunstan <andrew.dunstan@2ndquadrant.com>

35 files changed, 1768 insertions, 52 deletions

diff --git a/src/backend/commands/functioncmds.c b/src/backend/commands/functioncmds.c
index ea08c3237c1..df87dfeb543 100644
--- a/src/backend/commands/functioncmds.c
+++ b/src/backend/commands/functioncmds.c
@@ -65,6 +65,7 @@
 #include "utils/fmgroids.h"
 #include "utils/guc.h"
 #include "utils/lsyscache.h"
+#include "utils/memutils.h"
 #include "utils/rel.h"
 #include "utils/syscache.h"
 #include "utils/tqual.h"
@@ -2136,9 +2137,11 @@ IsThereFunctionInNamespace(const char *proname, int pronargs,
 /*
  * ExecuteDoStmt
  *		Execute inline procedural-language code
+ *
+ * See at ExecuteCallStmt() about the atomic argument.
  */
 void
-ExecuteDoStmt(DoStmt *stmt)
+ExecuteDoStmt(DoStmt *stmt, bool atomic)
 {
 	InlineCodeBlock *codeblock = makeNode(InlineCodeBlock);
 	ListCell   *arg;
@@ -2200,6 +2203,7 @@ ExecuteDoStmt(DoStmt *stmt)
 	codeblock->langOid = HeapTupleGetOid(languageTuple);
 	languageStruct = (Form_pg_language) GETSTRUCT(languageTuple);
 	codeblock->langIsTrusted = languageStruct->lanpltrusted;
+	codeblock->atomic = atomic;
 
 	if (languageStruct->lanpltrusted)
 	{
@@ -2236,9 +2240,28 @@ ExecuteDoStmt(DoStmt *stmt)
 
 /*
  * Execute CALL statement
+ *
+ * Inside a top-level CALL statement, transaction-terminating commands such as
+ * COMMIT or a PL-specific equivalent are allowed.  The terminology in the SQL
+ * standard is that CALL establishes a non-atomic execution context.  Most
+ * other commands establish an atomic execution context, in which transaction
+ * control actions are not allowed.  If there are nested executions of CALL,
+ * we want to track the execution context recursively, so that the nested
+ * CALLs can also do transaction control.  Note, however, that for example in
+ * CALL -> SELECT -> CALL, the second call cannot do transaction control,
+ * because the SELECT in between establishes an atomic execution context.
+ *
+ * So when ExecuteCallStmt() is called from the top level, we pass in atomic =
+ * false (recall that that means transactions = yes).  We then create a
+ * CallContext node with content atomic = false, which is passed in the
+ * fcinfo->context field to the procedure invocation.  The language
+ * implementation should then take appropriate measures to allow or prevent
+ * transaction commands based on that information, e.g., call
+ * SPI_connect_ext(SPI_OPT_NONATOMIC).  The language should also pass on the
+ * atomic flag to any nested invocations to CALL.
  */
 void
-ExecuteCallStmt(ParseState *pstate, CallStmt *stmt)
+ExecuteCallStmt(ParseState *pstate, CallStmt *stmt, bool atomic)
 {
 	List	   *targs;
 	ListCell   *lc;
@@ -2249,6 +2272,8 @@ ExecuteCallStmt(ParseState *pstate, CallStmt *stmt)
 	AclResult   aclresult;
 	FmgrInfo	flinfo;
 	FunctionCallInfoData fcinfo;
+	CallContext *callcontext;
+	HeapTuple	tp;
 
 	targs = NIL;
 	foreach(lc, stmt->funccall->args)
@@ -2284,8 +2309,24 @@ ExecuteCallStmt(ParseState *pstate, CallStmt *stmt)
 							   FUNC_MAX_ARGS,
 							   FUNC_MAX_ARGS)));
 
+	callcontext = makeNode(CallContext);
+	callcontext->atomic = atomic;
+
+	/*
+	 * If proconfig is set we can't allow transaction commands because of the
+	 * way the GUC stacking works: The transaction boundary would have to pop
+	 * the proconfig setting off the stack.  That restriction could be lifted
+	 * by redesigning the GUC nesting mechanism a bit.
+	 */
+	tp = SearchSysCache1(PROCOID, ObjectIdGetDatum(fexpr->funcid));
+	if (!HeapTupleIsValid(tp))
+		elog(ERROR, "cache lookup failed for function %u", fexpr->funcid);
+	if (!heap_attisnull(tp, Anum_pg_proc_proconfig))
+		callcontext->atomic = true;
+	ReleaseSysCache(tp);
+
 	fmgr_info(fexpr->funcid, &flinfo);
-	InitFunctionCallInfoData(fcinfo, &flinfo, nargs, fexpr->inputcollid, NULL, NULL);
+	InitFunctionCallInfoData(fcinfo, &flinfo, nargs, fexpr->inputcollid, (Node *) callcontext, NULL);
 
 	i = 0;
 	foreach (lc, fexpr->args)
diff --git a/src/backend/executor/spi.c b/src/backend/executor/spi.c
index 995f67d2662..9fc4431b80c 100644
--- a/src/backend/executor/spi.c
+++ b/src/backend/executor/spi.c
@@ -83,6 +83,12 @@ static bool _SPI_checktuples(void);
 int
 SPI_connect(void)
 {
+	return SPI_connect_ext(0);
+}
+
+int
+SPI_connect_ext(int options)
+{
 	int			newdepth;
 
 	/* Enlarge stack if necessary */
@@ -92,7 +98,7 @@ SPI_connect(void)
 			elog(ERROR, "SPI stack corrupted");
 		newdepth = 16;
 		_SPI_stack = (_SPI_connection *)
-			MemoryContextAlloc(TopTransactionContext,
+			MemoryContextAlloc(TopMemoryContext,
 							   newdepth * sizeof(_SPI_connection));
 		_SPI_stack_depth = newdepth;
 	}
@@ -124,19 +130,25 @@ SPI_connect(void)
 	_SPI_current->execCxt = NULL;
 	_SPI_current->connectSubid = GetCurrentSubTransactionId();
 	_SPI_current->queryEnv = NULL;
+	_SPI_current->atomic = (options & SPI_OPT_NONATOMIC ? false : true);
+	_SPI_current->internal_xact = false;
 
 	/*
 	 * Create memory contexts for this procedure
 	 *
-	 * XXX it would be better to use PortalContext as the parent context, but
-	 * we may not be inside a portal (consider deferred-trigger execution).
-	 * Perhaps CurTransactionContext would do?	For now it doesn't matter
-	 * because we clean up explicitly in AtEOSubXact_SPI().
+	 * In atomic contexts (the normal case), we use TopTransactionContext,
+	 * otherwise PortalContext, so that it lives across transaction
+	 * boundaries.
+	 *
+	 * XXX It could be better to use PortalContext as the parent context in
+	 * all cases, but we may not be inside a portal (consider deferred-trigger
+	 * execution).  Perhaps CurTransactionContext could be an option?  For now
+	 * it doesn't matter because we clean up explicitly in AtEOSubXact_SPI().
 	 */
-	_SPI_current->procCxt = AllocSetContextCreate(TopTransactionContext,
+	_SPI_current->procCxt = AllocSetContextCreate(_SPI_current->atomic ? TopTransactionContext : PortalContext,
 												  "SPI Proc",
 												  ALLOCSET_DEFAULT_SIZES);
-	_SPI_current->execCxt = AllocSetContextCreate(TopTransactionContext,
+	_SPI_current->execCxt = AllocSetContextCreate(_SPI_current->atomic ? TopTransactionContext : _SPI_current->procCxt,
 												  "SPI Exec",
 												  ALLOCSET_DEFAULT_SIZES);
 	/* ... and switch to procedure's context */
@@ -181,6 +193,73 @@ SPI_finish(void)
 	return SPI_OK_FINISH;
 }
 
+void
+SPI_start_transaction(void)
+{
+	MemoryContext oldcontext = CurrentMemoryContext;
+
+	StartTransactionCommand();
+	MemoryContextSwitchTo(oldcontext);
+}
+
+void
+SPI_commit(void)
+{
+	MemoryContext oldcontext = CurrentMemoryContext;
+
+	if (_SPI_current->atomic)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_TRANSACTION_TERMINATION),
+				 errmsg("invalid transaction termination")));
+
+	/*
+	 * This restriction is required by PLs implemented on top of SPI.  They
+	 * use subtransactions to establish exception blocks that are supposed to
+	 * be rolled back together if there is an error.  Terminating the
+	 * top-level transaction in such a block violates that idea.  A future PL
+	 * implementation might have different ideas about this, in which case
+	 * this restriction would have to be refined or the check possibly be
+	 * moved out of SPI into the PLs.
+	 */
+	if (IsSubTransaction())
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_TRANSACTION_TERMINATION),
+				 errmsg("cannot commit while a subtransaction is active")));
+
+	_SPI_current->internal_xact = true;
+
+	if (ActiveSnapshotSet())
+		PopActiveSnapshot();
+	CommitTransactionCommand();
+	MemoryContextSwitchTo(oldcontext);
+
+	_SPI_current->internal_xact = false;
+}
+
+void
+SPI_rollback(void)
+{
+	MemoryContext oldcontext = CurrentMemoryContext;
+
+	if (_SPI_current->atomic)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_TRANSACTION_TERMINATION),
+				 errmsg("invalid transaction termination")));
+
+	/* see under SPI_commit() */
+	if (IsSubTransaction())
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_TRANSACTION_TERMINATION),
+				 errmsg("cannot roll back while a subtransaction is active")));
+
+	_SPI_current->internal_xact = true;
+
+	AbortCurrentTransaction();
+	MemoryContextSwitchTo(oldcontext);
+
+	_SPI_current->internal_xact = false;
+}
+
 /*
  * Clean up SPI state at transaction commit or abort.
  */
@@ -188,6 +267,12 @@ void
 AtEOXact_SPI(bool isCommit)
 {
 	/*
+	 * Do nothing if the transaction end was initiated by SPI.
+	 */
+	if (_SPI_current && _SPI_current->internal_xact)
+		return;
+
+	/*
 	 * Note that memory contexts belonging to SPI stack entries will be freed
 	 * automatically, so we can ignore them here.  We just need to restore our
 	 * static variables to initial state.
@@ -224,6 +309,9 @@ AtEOSubXact_SPI(bool isCommit, SubTransactionId mySubid)
 		if (connection->connectSubid != mySubid)
 			break;				/* couldn't be any underneath it either */
 
+		if (connection->internal_xact)
+			break;
+
 		found = true;
 
 		/*
diff --git a/src/backend/tcop/utility.c b/src/backend/tcop/utility.c
index 26df660f350..3abe7d6155a 100644
--- a/src/backend/tcop/utility.c
+++ b/src/backend/tcop/utility.c
@@ -530,7 +530,8 @@ standard_ProcessUtility(PlannedStmt *pstmt,
 			break;
 
 		case T_DoStmt:
-			ExecuteDoStmt((DoStmt *) parsetree);
+			ExecuteDoStmt((DoStmt *) parsetree,
+						  (context != PROCESS_UTILITY_TOPLEVEL || IsTransactionBlock()));
 			break;
 
 		case T_CreateTableSpaceStmt:
@@ -659,7 +660,8 @@ standard_ProcessUtility(PlannedStmt *pstmt,
 			break;
 
 		case T_CallStmt:
-			ExecuteCallStmt(pstate, castNode(CallStmt, parsetree));
+			ExecuteCallStmt(pstate, castNode(CallStmt, parsetree),
+							(context != PROCESS_UTILITY_TOPLEVEL || IsTransactionBlock()));
 			break;
 
 		case T_ClusterStmt:
diff --git a/src/backend/utils/mmgr/portalmem.c b/src/backend/utils/mmgr/portalmem.c
index 84c68ac1895..f3f0add1d6d 100644
--- a/src/backend/utils/mmgr/portalmem.c
+++ b/src/backend/utils/mmgr/portalmem.c
@@ -742,11 +742,8 @@ PreCommit_Portals(bool isPrepare)
 /*
  * Abort processing for portals.
  *
- * At this point we reset "active" status and run the cleanup hook if
- * present, but we can't release the portal's memory until the cleanup call.
- *
- * The reason we need to reset active is so that we can replace the unnamed
- * portal, else we'll fail to execute ROLLBACK when it arrives.
+ * At this point we run the cleanup hook if present, but we can't release the
+ * portal's memory until the cleanup call.
  */
 void
 AtAbort_Portals(void)
@@ -761,17 +758,6 @@ AtAbort_Portals(void)
 		Portal		portal = hentry->portal;
 
 		/*
-		 * See similar code in AtSubAbort_Portals().  This would fire if code
-		 * orchestrating multiple top-level transactions within a portal, such
-		 * as VACUUM, caught errors and continued under the same portal with a
-		 * fresh transaction.  No part of core PostgreSQL functions that way.
-		 * XXX Such code would wish the portal to remain ACTIVE, as in
-		 * PreCommit_Portals().
-		 */
-		if (portal->status == PORTAL_ACTIVE)
-			MarkPortalFailed(portal);
-
-		/*
 		 * Do nothing else to cursors held over from a previous transaction.
 		 */
 		if (portal->createSubid == InvalidSubTransactionId)
@@ -810,9 +796,10 @@ AtAbort_Portals(void)
 		 * Although we can't delete the portal data structure proper, we can
 		 * release any memory in subsidiary contexts, such as executor state.
 		 * The cleanup hook was the last thing that might have needed data
-		 * there.
+		 * there.  But leave active portals alone.
 		 */
-		MemoryContextDeleteChildren(portal->portalContext);
+		if (portal->status != PORTAL_ACTIVE)
+			MemoryContextDeleteChildren(portal->portalContext);
 	}
 }
 
@@ -832,6 +819,13 @@ AtCleanup_Portals(void)
 	{
 		Portal		portal = hentry->portal;
 
+		/*
+		 * Do not touch active portals --- this can only happen in the case of
+		 * a multi-transaction command.
+		 */
+		if (portal->status == PORTAL_ACTIVE)
+			continue;
+
 		/* Do nothing to cursors held over from a previous transaction */
 		if (portal->createSubid == InvalidSubTransactionId)
 		{
@@ -1161,3 +1155,22 @@ ThereAreNoReadyPortals(void)
 
 	return true;
 }
+
+bool
+ThereArePinnedPortals(void)
+{
+	HASH_SEQ_STATUS status;
+	PortalHashEnt *hentry;
+
+	hash_seq_init(&status, PortalHashTable);
+
+	while ((hentry = (PortalHashEnt *) hash_seq_search(&status)) != NULL)
+	{
+		Portal		portal = hentry->portal;
+
+		if (portal->portalPinned)
+			return true;
+	}
+
+	return false;
+}
diff --git a/src/include/commands/defrem.h b/src/include/commands/defrem.h
index 41007162aa5..7b824c95af3 100644
--- a/src/include/commands/defrem.h
+++ b/src/include/commands/defrem.h
@@ -59,8 +59,8 @@ extern ObjectAddress CreateTransform(CreateTransformStmt *stmt);
 extern void DropTransformById(Oid transformOid);
 extern void IsThereFunctionInNamespace(const char *proname, int pronargs,
 						   oidvector *proargtypes, Oid nspOid);
-extern void ExecuteDoStmt(DoStmt *stmt);
-extern void ExecuteCallStmt(ParseState *pstate, CallStmt *stmt);
+extern void ExecuteDoStmt(DoStmt *stmt, bool atomic);
+extern void ExecuteCallStmt(ParseState *pstate, CallStmt *stmt, bool atomic);
 extern Oid	get_cast_oid(Oid sourcetypeid, Oid targettypeid, bool missing_ok);
 extern Oid	get_transform_oid(Oid type_id, Oid lang_id, bool missing_ok);
 extern void interpret_function_parameter_list(ParseState *pstate,
diff --git a/src/include/executor/spi.h b/src/include/executor/spi.h
index 43580c51585..e5bdaecc4e3 100644
--- a/src/include/executor/spi.h
+++ b/src/include/executor/spi.h
@@ -65,6 +65,8 @@ typedef struct _SPI_plan *SPIPlanPtr;
 #define SPI_OK_REL_UNREGISTER	16
 #define SPI_OK_TD_REGISTER		17
 
+#define SPI_OPT_NONATOMIC		(1 << 0)
+
 /* These used to be functions, now just no-ops for backwards compatibility */
 #define SPI_push()	((void) 0)
 #define SPI_pop()	((void) 0)
@@ -78,6 +80,7 @@ extern PGDLLIMPORT SPITupleTable *SPI_tuptable;
 extern PGDLLIMPORT int SPI_result;
 
 extern int	SPI_connect(void);
+extern int	SPI_connect_ext(int options);
 extern int	SPI_finish(void);
 extern int	SPI_execute(const char *src, bool read_only, long tcount);
 extern int SPI_execute_plan(SPIPlanPtr plan, Datum *Values, const char *Nulls,
@@ -156,6 +159,10 @@ extern int	SPI_register_relation(EphemeralNamedRelation enr);
 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 AtEOXact_SPI(bool isCommit);
 extern void AtEOSubXact_SPI(bool isCommit, SubTransactionId mySubid);
 
diff --git a/src/include/executor/spi_priv.h b/src/include/executor/spi_priv.h
index 64f8a450eb5..263c8f14539 100644
--- a/src/include/executor/spi_priv.h
+++ b/src/include/executor/spi_priv.h
@@ -36,6 +36,10 @@ typedef struct
 	MemoryContext savedcxt;		/* context of SPI_connect's caller */
 	SubTransactionId connectSubid;	/* ID of connecting subtransaction */
 	QueryEnvironment *queryEnv; /* query environment setup for SPI level */
+
+	/* transaction management support */
+	bool		atomic;			/* atomic execution context, does not allow transactions */
+	bool		internal_xact;	/* SPI-managed transaction boundary, skip cleanup */
 } _SPI_connection;
 
 /*
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index 2eb3d6d3711..74b094a9c39 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -500,7 +500,8 @@ typedef enum NodeTag
 	T_FdwRoutine,				/* in foreign/fdwapi.h */
 	T_IndexAmRoutine,			/* in access/amapi.h */
 	T_TsmRoutine,				/* in access/tsmapi.h */
-	T_ForeignKeyCacheInfo		/* in utils/rel.h */
+	T_ForeignKeyCacheInfo,		/* in utils/rel.h */
+	T_CallContext				/* in nodes/parsenodes.h */
 } NodeTag;
 
 /*
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 93122adae85..bbacbe144c8 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -2789,6 +2789,7 @@ typedef struct InlineCodeBlock
 	char	   *source_text;	/* source text of anonymous code block */
 	Oid			langOid;		/* OID of selected language */
 	bool		langIsTrusted;	/* trusted property of the language */
+	bool		atomic;			/* atomic execution context */
 } InlineCodeBlock;
 
 /* ----------------------
@@ -2801,6 +2802,12 @@ typedef struct CallStmt
 	FuncCall   *funccall;
 } CallStmt;
 
+typedef struct CallContext
+{
+	NodeTag		type;
+	bool		atomic;
+} CallContext;
+
 /* ----------------------
  *		Alter Object Rename Statement
  * ----------------------
diff --git a/src/include/utils/portal.h b/src/include/utils/portal.h
index bc9d52e506e..b903cb0fbe1 100644
--- a/src/include/utils/portal.h
+++ b/src/include/utils/portal.h
@@ -231,5 +231,6 @@ extern PlannedStmt *PortalGetPrimaryStmt(Portal portal);
 extern void PortalCreateHoldStore(Portal portal);
 extern void PortalHashTableDeleteAll(void);
 extern bool ThereAreNoReadyPortals(void);
+extern bool ThereArePinnedPortals(void);
 
 #endif							/* PORTAL_H */
diff --git a/src/pl/plperl/GNUmakefile b/src/pl/plperl/GNUmakefile
index b829027d05d..933abb47c49 100644
--- a/src/pl/plperl/GNUmakefile
+++ b/src/pl/plperl/GNUmakefile
@@ -55,7 +55,7 @@ endif # win32
 SHLIB_LINK = $(perl_embed_ldflags)
 
 REGRESS_OPTS = --dbname=$(PL_TESTDB) --load-extension=plperl  --load-extension=plperlu
-REGRESS = plperl plperl_lc plperl_trigger plperl_shared plperl_elog plperl_util plperl_init plperlu plperl_array plperl_call
+REGRESS = plperl plperl_lc plperl_trigger plperl_shared plperl_elog plperl_util plperl_init plperlu plperl_array plperl_call plperl_transaction
 # if Perl can support two interpreters in one backend,
 # test plperl-and-plperlu cases
 ifneq ($(PERL),)
diff --git a/src/pl/plperl/SPI.xs b/src/pl/plperl/SPI.xs
index d9e6f579d41..b98c547e8be 100644
--- a/src/pl/plperl/SPI.xs
+++ b/src/pl/plperl/SPI.xs
@@ -152,6 +152,15 @@ spi_spi_cursor_close(sv)
 		plperl_spi_cursor_close(cursor);
 		pfree(cursor);
 
+void
+spi_spi_commit()
+	CODE:
+		plperl_spi_commit();
+
+void
+spi_spi_rollback()
+	CODE:
+		plperl_spi_rollback();
 
 BOOT:
     items = 0;  /* avoid 'unused variable' warning */
diff --git a/src/pl/plperl/expected/plperl_transaction.out b/src/pl/plperl/expected/plperl_transaction.out
new file mode 100644
index 00000000000..bd7b7f8660b
--- /dev/null
+++ b/src/pl/plperl/expected/plperl_transaction.out
@@ -0,0 +1,133 @@
+CREATE TABLE test1 (a int, b text);
+CREATE PROCEDURE transaction_test1()
+LANGUAGE plperl
+AS $$
+foreach my $i (0..9) {
+    spi_exec_query("INSERT INTO test1 (a) VALUES ($i)");
+    if ($i % 2 == 0) {
+        spi_commit();
+    } else {
+        spi_rollback();
+    }
+}
+$$;
+CALL transaction_test1();
+SELECT * FROM test1;
+ a | b 
+---+---
+ 0 | 
+ 2 | 
+ 4 | 
+ 6 | 
+ 8 | 
+(5 rows)
+
+TRUNCATE test1;
+DO
+LANGUAGE plperl
+$$
+foreach my $i (0..9) {
+    spi_exec_query("INSERT INTO test1 (a) VALUES ($i)");
+    if ($i % 2 == 0) {
+        spi_commit();
+    } else {
+        spi_rollback();
+    }
+}
+$$;
+SELECT * FROM test1;
+ a | b 
+---+---
+ 0 | 
+ 2 | 
+ 4 | 
+ 6 | 
+ 8 | 
+(5 rows)
+
+TRUNCATE test1;
+-- not allowed in a function
+CREATE FUNCTION transaction_test2() RETURNS int
+LANGUAGE plperl
+AS $$
+foreach my $i (0..9) {
+    spi_exec_query("INSERT INTO test1 (a) VALUES ($i)");
+    if ($i % 2 == 0) {
+        spi_commit();
+    } else {
+        spi_rollback();
+    }
+}
+return 1;
+$$;
+SELECT transaction_test2();
+ERROR:  invalid transaction termination at line 5.
+CONTEXT:  PL/Perl function "transaction_test2"
+SELECT * FROM test1;
+ a | b 
+---+---
+(0 rows)
+
+-- also not allowed if procedure is called from a function
+CREATE FUNCTION transaction_test3() RETURNS int
+LANGUAGE plperl
+AS $$
+spi_exec_query("CALL transaction_test1()");
+return 1;
+$$;
+SELECT transaction_test3();
+ERROR:  invalid transaction termination at line 5. at line 2.
+CONTEXT:  PL/Perl function "transaction_test3"
+SELECT * FROM test1;
+ a | b 
+---+---
+(0 rows)
+
+-- DO block inside function
+CREATE FUNCTION transaction_test4() RETURNS int
+LANGUAGE plperl
+AS $$
+spi_exec_query('DO LANGUAGE plperl $x$ spi_commit(); $x$');
+return 1;
+$$;
+SELECT transaction_test4();
+ERROR:  invalid transaction termination at line 1. at line 2.
+CONTEXT:  PL/Perl function "transaction_test4"
+-- commit inside cursor loop
+CREATE TABLE test2 (x int);
+INSERT INTO test2 VALUES (0), (1), (2), (3), (4);
+TRUNCATE test1;
+DO LANGUAGE plperl $$
+my $sth = spi_query("SELECT * FROM test2 ORDER BY x");
+my $row;
+while (defined($row = spi_fetchrow($sth))) {
+    spi_exec_query("INSERT INTO test1 (a) VALUES (" . $row->{x} . ")");
+    spi_commit();
+}
+$$;
+ERROR:  cannot commit transaction while a cursor is open at line 6.
+CONTEXT:  PL/Perl anonymous code block
+SELECT * FROM test1;
+ a | b 
+---+---
+(0 rows)
+
+-- rollback inside cursor loop
+TRUNCATE test1;
+DO LANGUAGE plperl $$
+my $sth = spi_query("SELECT * FROM test2 ORDER BY x");
+my $row;
+while (defined($row = spi_fetchrow($sth))) {
+    spi_exec_query("INSERT INTO test1 (a) VALUES (" . $row->{x} . ")");
+    spi_rollback();
+}
+$$;
+ERROR:  cannot abort transaction while a cursor is open at line 6.
+CONTEXT:  PL/Perl anonymous code block
+SELECT * FROM test1;
+ a | b 
+---+---
+(0 rows)
+
+DROP TABLE test1;
+DROP TABLE test2;
diff --git a/src/pl/plperl/plperl.c b/src/pl/plperl/plperl.c
index 10feef11cf3..77c41b28215 100644
--- a/src/pl/plperl/plperl.c
+++ b/src/pl/plperl/plperl.c
@@ -1929,7 +1929,7 @@ plperl_inline_handler(PG_FUNCTION_ARGS)
 
 		current_call_data = &this_call_data;
 
-		if (SPI_connect() != SPI_OK_CONNECT)
+		if (SPI_connect_ext(codeblock->atomic ? 0 : SPI_OPT_NONATOMIC) != SPI_OK_CONNECT)
 			elog(ERROR, "could not connect to SPI manager");
 
 		select_perl_context(desc.lanpltrusted);
@@ -2396,13 +2396,18 @@ plperl_call_perl_event_trigger_func(plperl_proc_desc *desc,
 static Datum
 plperl_func_handler(PG_FUNCTION_ARGS)
 {
+	bool		nonatomic;
 	plperl_proc_desc *prodesc;
 	SV		   *perlret;
 	Datum		retval = 0;
 	ReturnSetInfo *rsi;
 	ErrorContextCallback pl_error_context;
 
-	if (SPI_connect() != SPI_OK_CONNECT)
+	nonatomic = fcinfo->context &&
+		IsA(fcinfo->context, CallContext) &&
+		!castNode(CallContext, fcinfo->context)->atomic;
+
+	if (SPI_connect_ext(nonatomic ? SPI_OPT_NONATOMIC : 0) != SPI_OK_CONNECT)
 		elog(ERROR, "could not connect to SPI manager");
 
 	prodesc = compile_plperl_function(fcinfo->flinfo->fn_oid, false, false);
@@ -3953,6 +3958,66 @@ plperl_spi_freeplan(char *query)
 	SPI_freeplan(plan);
 }
 
+void
+plperl_spi_commit(void)
+{
+	MemoryContext oldcontext = CurrentMemoryContext;
+
+	PG_TRY();
+	{
+		if (ThereArePinnedPortals())
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("cannot commit transaction while a cursor is open")));
+
+		SPI_commit();
+		SPI_start_transaction();
+	}
+	PG_CATCH();
+	{
+		ErrorData  *edata;
+
+		/* Save error info */
+		MemoryContextSwitchTo(oldcontext);
+		edata = CopyErrorData();
+		FlushErrorState();
+
+		/* Punt the error to Perl */
+		croak_cstr(edata->message);
+	}
+	PG_END_TRY();
+}
+
+void
+plperl_spi_rollback(void)
+{
+	MemoryContext oldcontext = CurrentMemoryContext;
+
+	PG_TRY();
+	{
+		if (ThereArePinnedPortals())
+			ereport(ERROR,
+					(errcode(ERRCODE_INVALID_TRANSACTION_TERMINATION),
+					 errmsg("cannot abort transaction while a cursor is open")));
+
+		SPI_rollback();
+		SPI_start_transaction();
+	}
+	PG_CATCH();
+	{
+		ErrorData  *edata;
+
+		/* Save error info */
+		MemoryContextSwitchTo(oldcontext);
+		edata = CopyErrorData();
+		FlushErrorState();
+
+		/* Punt the error to Perl */
+		croak_cstr(edata->message);
+	}
+	PG_END_TRY();
+}
+
 /*
  * Implementation of plperl's elog() function
  *
diff --git a/src/pl/plperl/plperl.h b/src/pl/plperl/plperl.h
index 78366aac04f..6fe7803088e 100644
--- a/src/pl/plperl/plperl.h
+++ b/src/pl/plperl/plperl.h
@@ -125,6 +125,8 @@ HV		   *plperl_spi_exec_prepared(char *, HV *, int, SV **);
 SV		   *plperl_spi_query_prepared(char *, int, SV **);
 void		plperl_spi_freeplan(char *);
 void		plperl_spi_cursor_close(char *);
+void		plperl_spi_commit(void);
+void		plperl_spi_rollback(void);
 char	   *plperl_sv_to_literal(SV *, char *);
 void		plperl_util_elog(int level, SV *msg);
 
diff --git a/src/pl/plperl/sql/plperl_transaction.sql b/src/pl/plperl/sql/plperl_transaction.sql
new file mode 100644
index 00000000000..5c14d4732eb
--- /dev/null
+++ b/src/pl/plperl/sql/plperl_transaction.sql
@@ -0,0 +1,120 @@
+CREATE TABLE test1 (a int, b text);
+
+
+CREATE PROCEDURE transaction_test1()
+LANGUAGE plperl
+AS $$
+foreach my $i (0..9) {
+    spi_exec_query("INSERT INTO test1 (a) VALUES ($i)");
+    if ($i % 2 == 0) {
+        spi_commit();
+    } else {
+        spi_rollback();
+    }
+}
+$$;
+
+CALL transaction_test1();
+
+SELECT * FROM test1;
+
+
+TRUNCATE test1;
+
+DO
+LANGUAGE plperl
+$$
+foreach my $i (0..9) {
+    spi_exec_query("INSERT INTO test1 (a) VALUES ($i)");
+    if ($i % 2 == 0) {
+        spi_commit();
+    } else {
+        spi_rollback();
+    }
+}
+$$;
+
+SELECT * FROM test1;
+
+
+TRUNCATE test1;
+
+-- not allowed in a function
+CREATE FUNCTION transaction_test2() RETURNS int
+LANGUAGE plperl
+AS $$
+foreach my $i (0..9) {
+    spi_exec_query("INSERT INTO test1 (a) VALUES ($i)");
+    if ($i % 2 == 0) {
+        spi_commit();
+    } else {
+        spi_rollback();
+    }
+}
+return 1;
+$$;
+
+SELECT transaction_test2();
+
+SELECT * FROM test1;
+
+
+-- also not allowed if procedure is called from a function
+CREATE FUNCTION transaction_test3() RETURNS int
+LANGUAGE plperl
+AS $$
+spi_exec_query("CALL transaction_test1()");
+return 1;
+$$;
+
+SELECT transaction_test3();
+
+SELECT * FROM test1;
+
+
+-- DO block inside function
+CREATE FUNCTION transaction_test4() RETURNS int
+LANGUAGE plperl
+AS $$
+spi_exec_query('DO LANGUAGE plperl $x$ spi_commit(); $x$');
+return 1;
+$$;
+
+SELECT transaction_test4();
+
+
+-- commit inside cursor loop
+CREATE TABLE test2 (x int);
+INSERT INTO test2 VALUES (0), (1), (2), (3), (4);
+
+TRUNCATE test1;
+
+DO LANGUAGE plperl $$
+my $sth = spi_query("SELECT * FROM test2 ORDER BY x");
+my $row;
+while (defined($row = spi_fetchrow($sth))) {
+    spi_exec_query("INSERT INTO test1 (a) VALUES (" . $row->{x} . ")");
+    spi_commit();
+}
+$$;
+
+SELECT * FROM test1;
+
+
+-- rollback inside cursor loop
+TRUNCATE test1;
+
+DO LANGUAGE plperl $$
+my $sth = spi_query("SELECT * FROM test2 ORDER BY x");
+my $row;
+while (defined($row = spi_fetchrow($sth))) {
+    spi_exec_query("INSERT INTO test1 (a) VALUES (" . $row->{x} . ")");
+    spi_rollback();
+}
+$$;
+
+SELECT * FROM test1;
+
+
+DROP TABLE test1;
+DROP TABLE test2;
diff --git a/src/pl/plpgsql/src/Makefile b/src/pl/plpgsql/src/Makefile
index 14a4d835840..91e1ada7add 100644
--- a/src/pl/plpgsql/src/Makefile
+++ b/src/pl/plpgsql/src/Makefile
@@ -26,7 +26,7 @@ DATA = plpgsql.control plpgsql--1.0.sql plpgsql--unpackaged--1.0.sql
 
 REGRESS_OPTS = --dbname=$(PL_TESTDB)
 
-REGRESS = plpgsql_call plpgsql_control
+REGRESS = plpgsql_call plpgsql_control plpgsql_transaction
 
 all: all-lib
 
diff --git a/src/pl/plpgsql/src/expected/plpgsql_transaction.out b/src/pl/plpgsql/src/expected/plpgsql_transaction.out
new file mode 100644
index 00000000000..8ec22c646c2
--- /dev/null
+++ b/src/pl/plpgsql/src/expected/plpgsql_transaction.out
@@ -0,0 +1,241 @@
+CREATE TABLE test1 (a int, b text);
+CREATE PROCEDURE transaction_test1()
+LANGUAGE plpgsql
+AS $$
+BEGIN
+    FOR i IN 0..9 LOOP
+        INSERT INTO test1 (a) VALUES (i);
+        IF i % 2 = 0 THEN
+            COMMIT;
+        ELSE
+            ROLLBACK;
+        END IF;
+    END LOOP;
+END
+$$;
+CALL transaction_test1();
+SELECT * FROM test1;
+ a | b 
+---+---
+ 0 | 
+ 2 | 
+ 4 | 
+ 6 | 
+ 8 | 
+(5 rows)
+
+TRUNCATE test1;
+DO
+LANGUAGE plpgsql
+$$
+BEGIN
+    FOR i IN 0..9 LOOP
+        INSERT INTO test1 (a) VALUES (i);
+        IF i % 2 = 0 THEN
+            COMMIT;
+        ELSE
+            ROLLBACK;
+        END IF;
+    END LOOP;
+END
+$$;
+SELECT * FROM test1;
+ a | b 
+---+---
+ 0 | 
+ 2 | 
+ 4 | 
+ 6 | 
+ 8 | 
+(5 rows)
+
+-- transaction commands not allowed when called in transaction block
+START TRANSACTION;
+CALL transaction_test1();
+ERROR:  invalid transaction termination
+CONTEXT:  PL/pgSQL function transaction_test1() line 6 at COMMIT
+COMMIT;
+START TRANSACTION;
+DO LANGUAGE plpgsql $$ BEGIN COMMIT; END $$;
+ERROR:  invalid transaction termination
+CONTEXT:  PL/pgSQL function inline_code_block line 1 at COMMIT
+COMMIT;
+TRUNCATE test1;
+-- not allowed in a function
+CREATE FUNCTION transaction_test2() RETURNS int
+LANGUAGE plpgsql
+AS $$
+BEGIN
+    FOR i IN 0..9 LOOP
+        INSERT INTO test1 (a) VALUES (i);
+        IF i % 2 = 0 THEN
+            COMMIT;
+        ELSE
+            ROLLBACK;
+        END IF;
+    END LOOP;
+    RETURN 1;
+END
+$$;
+SELECT transaction_test2();
+ERROR:  invalid transaction termination
+CONTEXT:  PL/pgSQL function transaction_test2() line 6 at COMMIT
+SELECT * FROM test1;
+ a | b 
+---+---
+(0 rows)
+
+-- also not allowed if procedure is called from a function
+CREATE FUNCTION transaction_test3() RETURNS int
+LANGUAGE plpgsql
+AS $$
+BEGIN
+    CALL transaction_test1();
+    RETURN 1;
+END;
+$$;
+SELECT transaction_test3();
+ERROR:  invalid transaction termination
+CONTEXT:  PL/pgSQL function transaction_test1() line 6 at COMMIT
+SQL statement "CALL transaction_test1()"
+PL/pgSQL function transaction_test3() line 3 at SQL statement
+SELECT * FROM test1;
+ a | b 
+---+---
+(0 rows)
+
+-- DO block inside function
+CREATE FUNCTION transaction_test4() RETURNS int
+LANGUAGE plpgsql
+AS $$
+BEGIN
+    EXECUTE 'DO LANGUAGE plpgsql $x$ BEGIN COMMIT; END $x$';
+    RETURN 1;
+END;
+$$;
+SELECT transaction_test4();
+ERROR:  invalid transaction termination
+CONTEXT:  PL/pgSQL function inline_code_block line 1 at COMMIT
+SQL statement "DO LANGUAGE plpgsql $x$ BEGIN COMMIT; END $x$"
+PL/pgSQL function transaction_test4() line 3 at EXECUTE
+-- proconfig settings currently disallow transaction statements
+CREATE PROCEDURE transaction_test5()
+LANGUAGE plpgsql
+SET work_mem = 555
+AS $$
+BEGIN
+    COMMIT;
+END;
+$$;
+CALL transaction_test5();
+ERROR:  invalid transaction termination
+CONTEXT:  PL/pgSQL function transaction_test5() line 3 at COMMIT
+-- commit inside cursor loop
+CREATE TABLE test2 (x int);
+INSERT INTO test2 VALUES (0), (1), (2), (3), (4);
+TRUNCATE test1;
+DO LANGUAGE plpgsql $$
+DECLARE
+    r RECORD;
+BEGIN
+    FOR r IN SELECT * FROM test2 ORDER BY x LOOP
+        INSERT INTO test1 (a) VALUES (r.x);
+        COMMIT;
+    END LOOP;
+END;
+$$;
+ERROR:  committing inside a cursor loop is not supported
+CONTEXT:  PL/pgSQL function inline_code_block line 7 at COMMIT
+SELECT * FROM test1;
+ a | b 
+---+---
+(0 rows)
+
+-- rollback inside cursor loop
+TRUNCATE test1;
+DO LANGUAGE plpgsql $$
+DECLARE
+    r RECORD;
+BEGIN
+    FOR r IN SELECT * FROM test2 ORDER BY x LOOP
+        INSERT INTO test1 (a) VALUES (r.x);
+        ROLLBACK;
+    END LOOP;
+END;
+$$;
+ERROR:  cannot abort transaction inside a cursor loop
+CONTEXT:  PL/pgSQL function inline_code_block line 7 at ROLLBACK
+SELECT * FROM test1;
+ a | b 
+---+---
+(0 rows)
+
+-- commit inside block with exception handler
+TRUNCATE test1;
+DO LANGUAGE plpgsql $$
+BEGIN
+    BEGIN
+        INSERT INTO test1 (a) VALUES (1);
+        COMMIT;
+        INSERT INTO test1 (a) VALUES (1/0);
+        COMMIT;
+    EXCEPTION
+        WHEN division_by_zero THEN
+            RAISE NOTICE 'caught division_by_zero';
+    END;
+END;
+$$;
+ERROR:  cannot commit while a subtransaction is active
+CONTEXT:  PL/pgSQL function inline_code_block line 5 at COMMIT
+SELECT * FROM test1;
+ a | b 
+---+---
+(0 rows)
+
+-- rollback inside block with exception handler
+TRUNCATE test1;
+DO LANGUAGE plpgsql $$
+BEGIN
+    BEGIN
+        INSERT INTO test1 (a) VALUES (1);
+        ROLLBACK;
+        INSERT INTO test1 (a) VALUES (1/0);
+        ROLLBACK;
+    EXCEPTION
+        WHEN division_by_zero THEN
+            RAISE NOTICE 'caught division_by_zero';
+    END;
+END;
+$$;
+ERROR:  cannot roll back while a subtransaction is active
+CONTEXT:  PL/pgSQL function inline_code_block line 5 at ROLLBACK
+SELECT * FROM test1;
+ a | b 
+---+---
+(0 rows)
+
+-- COMMIT failures
+DO LANGUAGE plpgsql $$
+BEGIN
+    CREATE TABLE test3 (y int UNIQUE DEFERRABLE INITIALLY DEFERRED);
+    COMMIT;
+    INSERT INTO test3 (y) VALUES (1);
+    COMMIT;
+    INSERT INTO test3 (y) VALUES (1);
+    INSERT INTO test3 (y) VALUES (2);
+    COMMIT;
+    INSERT INTO test3 (y) VALUES (3);  -- won't get here
+END;
+$$;
+ERROR:  duplicate key value violates unique constraint "test3_y_key"
+DETAIL:  Key (y)=(1) already exists.
+CONTEXT:  PL/pgSQL function inline_code_block line 9 at COMMIT
+SELECT * FROM test3;
+ y 
+---
+ 1
+(1 row)
+
+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 d096f242cdc..4478c5332e3 100644
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -290,6 +290,10 @@ static int exec_stmt_dynexecute(PLpgSQL_execstate *estate,
 					 PLpgSQL_stmt_dynexecute *stmt);
 static int exec_stmt_dynfors(PLpgSQL_execstate *estate,
 				  PLpgSQL_stmt_dynfors *stmt);
+static int exec_stmt_commit(PLpgSQL_execstate *estate,
+				PLpgSQL_stmt_commit *stmt);
+static int exec_stmt_rollback(PLpgSQL_execstate *estate,
+				PLpgSQL_stmt_rollback *stmt);
 
 static void plpgsql_estate_setup(PLpgSQL_execstate *estate,
 					 PLpgSQL_function *func,
@@ -1731,6 +1735,14 @@ exec_stmt(PLpgSQL_execstate *estate, PLpgSQL_stmt *stmt)
 			rc = exec_stmt_close(estate, (PLpgSQL_stmt_close *) stmt);
 			break;
 
+		case PLPGSQL_STMT_COMMIT:
+			rc = exec_stmt_commit(estate, (PLpgSQL_stmt_commit *) stmt);
+			break;
+
+		case PLPGSQL_STMT_ROLLBACK:
+			rc = exec_stmt_rollback(estate, (PLpgSQL_stmt_rollback *) stmt);
+			break;
+
 		default:
 			estate->err_stmt = save_estmt;
 			elog(ERROR, "unrecognized cmdtype: %d", stmt->cmd_type);
@@ -4264,6 +4276,57 @@ exec_stmt_close(PLpgSQL_execstate *estate, PLpgSQL_stmt_close *stmt)
 	return PLPGSQL_RC_OK;
 }
 
+/*
+ * exec_stmt_commit
+ *
+ * Commit the transaction.
+ */
+static int
+exec_stmt_commit(PLpgSQL_execstate *estate, PLpgSQL_stmt_commit *stmt)
+{
+	/*
+	 * XXX This could be implemented by converting the pinned portals to
+	 * holdable ones and organizing the cleanup separately.
+	 */
+	if (ThereArePinnedPortals())
+		ereport(ERROR,
+				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				 errmsg("committing inside a cursor loop is not supported")));
+
+	SPI_commit();
+	SPI_start_transaction();
+
+	estate->simple_eval_estate = NULL;
+	plpgsql_create_econtext(estate);
+
+	return PLPGSQL_RC_OK;
+}
+
+/*
+ * exec_stmt_rollback
+ *
+ * Abort the transaction.
+ */
+static int
+exec_stmt_rollback(PLpgSQL_execstate *estate, PLpgSQL_stmt_rollback *stmt)
+{
+	/*
+	 * Unlike the COMMIT case above, this might not make sense at all,
+	 * especially if the query driving the cursor loop has side effects.
+	 */
+	if (ThereArePinnedPortals())
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_TRANSACTION_TERMINATION),
+				 errmsg("cannot abort transaction inside a cursor loop")));
+
+	SPI_rollback();
+	SPI_start_transaction();
+
+	estate->simple_eval_estate = NULL;
+	plpgsql_create_econtext(estate);
+
+	return PLPGSQL_RC_OK;
+}
 
 /* ----------
  * exec_assign_expr			Put an expression's result into a variable.
@@ -6767,8 +6830,7 @@ plpgsql_xact_cb(XactEvent event, void *arg)
 	 */
 	if (event == XACT_EVENT_COMMIT || event == XACT_EVENT_PREPARE)
 	{
-		/* Shouldn't be any econtext stack entries left at commit */
-		Assert(simple_econtext_stack == NULL);
+		simple_econtext_stack = NULL;
 
 		if (shared_simple_eval_estate)
 			FreeExecutorState(shared_simple_eval_estate);
diff --git a/src/pl/plpgsql/src/pl_funcs.c b/src/pl/plpgsql/src/pl_funcs.c
index 80b8448b7fc..f0e85fcfcd9 100644
--- a/src/pl/plpgsql/src/pl_funcs.c
+++ b/src/pl/plpgsql/src/pl_funcs.c
@@ -284,6 +284,10 @@ plpgsql_stmt_typename(PLpgSQL_stmt *stmt)
 			return "CLOSE";
 		case PLPGSQL_STMT_PERFORM:
 			return "PERFORM";
+		case PLPGSQL_STMT_COMMIT:
+			return "COMMIT";
+		case PLPGSQL_STMT_ROLLBACK:
+			return "ROLLBACK";
 	}
 
 	return "unknown";
@@ -363,6 +367,8 @@ static void free_open(PLpgSQL_stmt_open *stmt);
 static void free_fetch(PLpgSQL_stmt_fetch *stmt);
 static void free_close(PLpgSQL_stmt_close *stmt);
 static void free_perform(PLpgSQL_stmt_perform *stmt);
+static void free_commit(PLpgSQL_stmt_commit *stmt);
+static void free_rollback(PLpgSQL_stmt_rollback *stmt);
 static void free_expr(PLpgSQL_expr *expr);
 
 
@@ -443,6 +449,12 @@ free_stmt(PLpgSQL_stmt *stmt)
 		case PLPGSQL_STMT_PERFORM:
 			free_perform((PLpgSQL_stmt_perform *) stmt);
 			break;
+		case PLPGSQL_STMT_COMMIT:
+			free_commit((PLpgSQL_stmt_commit *) stmt);
+			break;
+		case PLPGSQL_STMT_ROLLBACK:
+			free_rollback((PLpgSQL_stmt_rollback *) stmt);
+			break;
 		default:
 			elog(ERROR, "unrecognized cmd_type: %d", stmt->cmd_type);
 			break;
@@ -591,6 +603,16 @@ free_perform(PLpgSQL_stmt_perform *stmt)
 }
 
 static void
+free_commit(PLpgSQL_stmt_commit *stmt)
+{
+}
+
+static void
+free_rollback(PLpgSQL_stmt_rollback *stmt)
+{
+}
+
+static void
 free_exit(PLpgSQL_stmt_exit *stmt)
 {
 	free_expr(stmt->cond);
@@ -777,6 +799,8 @@ static void dump_fetch(PLpgSQL_stmt_fetch *stmt);
 static void dump_cursor_direction(PLpgSQL_stmt_fetch *stmt);
 static void dump_close(PLpgSQL_stmt_close *stmt);
 static void dump_perform(PLpgSQL_stmt_perform *stmt);
+static void dump_commit(PLpgSQL_stmt_commit *stmt);
+static void dump_rollback(PLpgSQL_stmt_rollback *stmt);
 static void dump_expr(PLpgSQL_expr *expr);
 
 
@@ -867,6 +891,12 @@ dump_stmt(PLpgSQL_stmt *stmt)
 		case PLPGSQL_STMT_PERFORM:
 			dump_perform((PLpgSQL_stmt_perform *) stmt);
 			break;
+		case PLPGSQL_STMT_COMMIT:
+			dump_commit((PLpgSQL_stmt_commit *) stmt);
+			break;
+		case PLPGSQL_STMT_ROLLBACK:
+			dump_rollback((PLpgSQL_stmt_rollback *) stmt);
+			break;
 		default:
 			elog(ERROR, "unrecognized cmd_type: %d", stmt->cmd_type);
 			break;
@@ -1240,6 +1270,20 @@ dump_perform(PLpgSQL_stmt_perform *stmt)
 }
 
 static void
+dump_commit(PLpgSQL_stmt_commit *stmt)
+{
+	dump_ind();
+	printf("COMMIT\n");
+}
+
+static void
+dump_rollback(PLpgSQL_stmt_rollback *stmt)
+{
+	dump_ind();
+	printf("ROLLBACK\n");
+}
+
+static void
 dump_exit(PLpgSQL_stmt_exit *stmt)
 {
 	dump_ind();
diff --git a/src/pl/plpgsql/src/pl_gram.y b/src/pl/plpgsql/src/pl_gram.y
index d9cab1ad7ee..42f6a2e1618 100644
--- a/src/pl/plpgsql/src/pl_gram.y
+++ b/src/pl/plpgsql/src/pl_gram.y
@@ -198,6 +198,7 @@ static	void			check_raise_parameters(PLpgSQL_stmt_raise *stmt);
 %type <stmt>	stmt_return stmt_raise stmt_assert stmt_execsql
 %type <stmt>	stmt_dynexecute stmt_for stmt_perform stmt_getdiag
 %type <stmt>	stmt_open stmt_fetch stmt_move stmt_close stmt_null
+%type <stmt>	stmt_commit stmt_rollback
 %type <stmt>	stmt_case stmt_foreach_a
 
 %type <list>	proc_exceptions
@@ -260,6 +261,7 @@ static	void			check_raise_parameters(PLpgSQL_stmt_raise *stmt);
 %token <keyword>	K_COLLATE
 %token <keyword>	K_COLUMN
 %token <keyword>	K_COLUMN_NAME
+%token <keyword>	K_COMMIT
 %token <keyword>	K_CONSTANT
 %token <keyword>	K_CONSTRAINT
 %token <keyword>	K_CONSTRAINT_NAME
@@ -325,6 +327,7 @@ static	void			check_raise_parameters(PLpgSQL_stmt_raise *stmt);
 %token <keyword>	K_RETURN
 %token <keyword>	K_RETURNED_SQLSTATE
 %token <keyword>	K_REVERSE
+%token <keyword>	K_ROLLBACK
 %token <keyword>	K_ROW_COUNT
 %token <keyword>	K_ROWTYPE
 %token <keyword>	K_SCHEMA
@@ -897,6 +900,10 @@ proc_stmt		: pl_block ';'
 						{ $$ = $1; }
 				| stmt_null
 						{ $$ = $1; }
+				| stmt_commit
+						{ $$ = $1; }
+				| stmt_rollback
+						{ $$ = $1; }
 				;
 
 stmt_perform	: K_PERFORM expr_until_semi
@@ -2151,6 +2158,31 @@ stmt_null		: K_NULL ';'
 					}
 				;
 
+stmt_commit		: K_COMMIT ';'
+					{
+						PLpgSQL_stmt_commit *new;
+
+						new = palloc(sizeof(PLpgSQL_stmt_commit));
+						new->cmd_type = PLPGSQL_STMT_COMMIT;
+						new->lineno = plpgsql_location_to_lineno(@1);
+
+						$$ = (PLpgSQL_stmt *)new;
+					}
+				;
+
+stmt_rollback	: K_ROLLBACK ';'
+					{
+						PLpgSQL_stmt_rollback *new;
+
+						new = palloc(sizeof(PLpgSQL_stmt_rollback));
+						new->cmd_type = PLPGSQL_STMT_ROLLBACK;
+						new->lineno = plpgsql_location_to_lineno(@1);
+
+						$$ = (PLpgSQL_stmt *)new;
+					}
+				;
+
+
 cursor_variable	: T_DATUM
 					{
 						/*
@@ -2387,6 +2419,7 @@ unreserved_keyword	:
 				| K_COLLATE
 				| K_COLUMN
 				| K_COLUMN_NAME
+				| K_COMMIT
 				| K_CONSTANT
 				| K_CONSTRAINT
 				| K_CONSTRAINT_NAME
@@ -2438,6 +2471,7 @@ unreserved_keyword	:
 				| K_RETURN
 				| K_RETURNED_SQLSTATE
 				| K_REVERSE
+				| K_ROLLBACK
 				| K_ROW_COUNT
 				| K_ROWTYPE
 				| K_SCHEMA
diff --git a/src/pl/plpgsql/src/pl_handler.c b/src/pl/plpgsql/src/pl_handler.c
index 4c2ba2f734f..c49428d9233 100644
--- a/src/pl/plpgsql/src/pl_handler.c
+++ b/src/pl/plpgsql/src/pl_handler.c
@@ -219,15 +219,20 @@ PG_FUNCTION_INFO_V1(plpgsql_call_handler);
 Datum
 plpgsql_call_handler(PG_FUNCTION_ARGS)
 {
+	bool		nonatomic;
 	PLpgSQL_function *func;
 	PLpgSQL_execstate *save_cur_estate;
 	Datum		retval;
 	int			rc;
 
+	nonatomic = fcinfo->context &&
+		IsA(fcinfo->context, CallContext) &&
+		!castNode(CallContext, fcinfo->context)->atomic;
+
 	/*
 	 * Connect to SPI manager
 	 */
-	if ((rc = SPI_connect()) != SPI_OK_CONNECT)
+	if ((rc = SPI_connect_ext(nonatomic ? SPI_OPT_NONATOMIC : 0)) != SPI_OK_CONNECT)
 		elog(ERROR, "SPI_connect failed: %s", SPI_result_code_string(rc));
 
 	/* Find or compile the function */
@@ -301,7 +306,7 @@ plpgsql_inline_handler(PG_FUNCTION_ARGS)
 	/*
 	 * Connect to SPI manager
 	 */
-	if ((rc = SPI_connect()) != SPI_OK_CONNECT)
+	if ((rc = SPI_connect_ext(codeblock->atomic ? 0 : SPI_OPT_NONATOMIC)) != SPI_OK_CONNECT)
 		elog(ERROR, "SPI_connect failed: %s", SPI_result_code_string(rc));
 
 	/* Compile the anonymous code block */
diff --git a/src/pl/plpgsql/src/pl_scanner.c b/src/pl/plpgsql/src/pl_scanner.c
index ee9aef8bbc0..12a3e6b818f 100644
--- a/src/pl/plpgsql/src/pl_scanner.c
+++ b/src/pl/plpgsql/src/pl_scanner.c
@@ -106,6 +106,7 @@ static const ScanKeyword unreserved_keywords[] = {
 	PG_KEYWORD("collate", K_COLLATE, UNRESERVED_KEYWORD)
 	PG_KEYWORD("column", K_COLUMN, UNRESERVED_KEYWORD)
 	PG_KEYWORD("column_name", K_COLUMN_NAME, UNRESERVED_KEYWORD)
+	PG_KEYWORD("commit", K_COMMIT, UNRESERVED_KEYWORD)
 	PG_KEYWORD("constant", K_CONSTANT, UNRESERVED_KEYWORD)
 	PG_KEYWORD("constraint", K_CONSTRAINT, UNRESERVED_KEYWORD)
 	PG_KEYWORD("constraint_name", K_CONSTRAINT_NAME, UNRESERVED_KEYWORD)
@@ -158,6 +159,7 @@ static const ScanKeyword unreserved_keywords[] = {
 	PG_KEYWORD("return", K_RETURN, UNRESERVED_KEYWORD)
 	PG_KEYWORD("returned_sqlstate", K_RETURNED_SQLSTATE, UNRESERVED_KEYWORD)
 	PG_KEYWORD("reverse", K_REVERSE, UNRESERVED_KEYWORD)
+	PG_KEYWORD("rollback", K_ROLLBACK, UNRESERVED_KEYWORD)
 	PG_KEYWORD("row_count", K_ROW_COUNT, UNRESERVED_KEYWORD)
 	PG_KEYWORD("rowtype", K_ROWTYPE, UNRESERVED_KEYWORD)
 	PG_KEYWORD("schema", K_SCHEMA, UNRESERVED_KEYWORD)
diff --git a/src/pl/plpgsql/src/plpgsql.h b/src/pl/plpgsql/src/plpgsql.h
index c571afa34bb..a9b9d91de7a 100644
--- a/src/pl/plpgsql/src/plpgsql.h
+++ b/src/pl/plpgsql/src/plpgsql.h
@@ -105,7 +105,9 @@ typedef enum PLpgSQL_stmt_type
 	PLPGSQL_STMT_OPEN,
 	PLPGSQL_STMT_FETCH,
 	PLPGSQL_STMT_CLOSE,
-	PLPGSQL_STMT_PERFORM
+	PLPGSQL_STMT_PERFORM,
+	PLPGSQL_STMT_COMMIT,
+	PLPGSQL_STMT_ROLLBACK
 } PLpgSQL_stmt_type;
 
 /*
@@ -434,6 +436,24 @@ typedef struct PLpgSQL_stmt_perform
 } PLpgSQL_stmt_perform;
 
 /*
+ * COMMIT statement
+ */
+typedef struct PLpgSQL_stmt_commit
+{
+	PLpgSQL_stmt_type cmd_type;
+	int			lineno;
+} PLpgSQL_stmt_commit;
+
+/*
+ * ROLLBACK statement
+ */
+typedef struct PLpgSQL_stmt_rollback
+{
+	PLpgSQL_stmt_type cmd_type;
+	int			lineno;
+} PLpgSQL_stmt_rollback;
+
+/*
  * GET DIAGNOSTICS item
  */
 typedef struct PLpgSQL_diag_item
diff --git a/src/pl/plpgsql/src/sql/plpgsql_transaction.sql b/src/pl/plpgsql/src/sql/plpgsql_transaction.sql
new file mode 100644
index 00000000000..02ee7350795
--- /dev/null
+++ b/src/pl/plpgsql/src/sql/plpgsql_transaction.sql
@@ -0,0 +1,215 @@
+CREATE TABLE test1 (a int, b text);
+
+
+CREATE PROCEDURE transaction_test1()
+LANGUAGE plpgsql
+AS $$
+BEGIN
+    FOR i IN 0..9 LOOP
+        INSERT INTO test1 (a) VALUES (i);
+        IF i % 2 = 0 THEN
+            COMMIT;
+        ELSE
+            ROLLBACK;
+        END IF;
+    END LOOP;
+END
+$$;
+
+CALL transaction_test1();
+
+SELECT * FROM test1;
+
+
+TRUNCATE test1;
+
+DO
+LANGUAGE plpgsql
+$$
+BEGIN
+    FOR i IN 0..9 LOOP
+        INSERT INTO test1 (a) VALUES (i);
+        IF i % 2 = 0 THEN
+            COMMIT;
+        ELSE
+            ROLLBACK;
+        END IF;
+    END LOOP;
+END
+$$;
+
+SELECT * FROM test1;
+
+
+-- transaction commands not allowed when called in transaction block
+START TRANSACTION;
+CALL transaction_test1();
+COMMIT;
+
+START TRANSACTION;
+DO LANGUAGE plpgsql $$ BEGIN COMMIT; END $$;
+COMMIT;
+
+
+TRUNCATE test1;
+
+-- not allowed in a function
+CREATE FUNCTION transaction_test2() RETURNS int
+LANGUAGE plpgsql
+AS $$
+BEGIN
+    FOR i IN 0..9 LOOP
+        INSERT INTO test1 (a) VALUES (i);
+        IF i % 2 = 0 THEN
+            COMMIT;
+        ELSE
+            ROLLBACK;
+        END IF;
+    END LOOP;
+    RETURN 1;
+END
+$$;
+
+SELECT transaction_test2();
+
+SELECT * FROM test1;
+
+
+-- also not allowed if procedure is called from a function
+CREATE FUNCTION transaction_test3() RETURNS int
+LANGUAGE plpgsql
+AS $$
+BEGIN
+    CALL transaction_test1();
+    RETURN 1;
+END;
+$$;
+
+SELECT transaction_test3();
+
+SELECT * FROM test1;
+
+
+-- DO block inside function
+CREATE FUNCTION transaction_test4() RETURNS int
+LANGUAGE plpgsql
+AS $$
+BEGIN
+    EXECUTE 'DO LANGUAGE plpgsql $x$ BEGIN COMMIT; END $x$';
+    RETURN 1;
+END;
+$$;
+
+SELECT transaction_test4();
+
+
+-- proconfig settings currently disallow transaction statements
+CREATE PROCEDURE transaction_test5()
+LANGUAGE plpgsql
+SET work_mem = 555
+AS $$
+BEGIN
+    COMMIT;
+END;
+$$;
+
+CALL transaction_test5();
+
+
+-- commit inside cursor loop
+CREATE TABLE test2 (x int);
+INSERT INTO test2 VALUES (0), (1), (2), (3), (4);
+
+TRUNCATE test1;
+
+DO LANGUAGE plpgsql $$
+DECLARE
+    r RECORD;
+BEGIN
+    FOR r IN SELECT * FROM test2 ORDER BY x LOOP
+        INSERT INTO test1 (a) VALUES (r.x);
+        COMMIT;
+    END LOOP;
+END;
+$$;
+
+SELECT * FROM test1;
+
+
+-- rollback inside cursor loop
+TRUNCATE test1;
+
+DO LANGUAGE plpgsql $$
+DECLARE
+    r RECORD;
+BEGIN
+    FOR r IN SELECT * FROM test2 ORDER BY x LOOP
+        INSERT INTO test1 (a) VALUES (r.x);
+        ROLLBACK;
+    END LOOP;
+END;
+$$;
+
+SELECT * FROM test1;
+
+
+-- commit inside block with exception handler
+TRUNCATE test1;
+
+DO LANGUAGE plpgsql $$
+BEGIN
+    BEGIN
+        INSERT INTO test1 (a) VALUES (1);
+        COMMIT;
+        INSERT INTO test1 (a) VALUES (1/0);
+        COMMIT;
+    EXCEPTION
+        WHEN division_by_zero THEN
+            RAISE NOTICE 'caught division_by_zero';
+    END;
+END;
+$$;
+
+SELECT * FROM test1;
+
+
+-- rollback inside block with exception handler
+TRUNCATE test1;
+
+DO LANGUAGE plpgsql $$
+BEGIN
+    BEGIN
+        INSERT INTO test1 (a) VALUES (1);
+        ROLLBACK;
+        INSERT INTO test1 (a) VALUES (1/0);
+        ROLLBACK;
+    EXCEPTION
+        WHEN division_by_zero THEN
+            RAISE NOTICE 'caught division_by_zero';
+    END;
+END;
+$$;
+
+SELECT * FROM test1;
+
+
+-- COMMIT failures
+DO LANGUAGE plpgsql $$
+BEGIN
+    CREATE TABLE test3 (y int UNIQUE DEFERRABLE INITIALLY DEFERRED);
+    COMMIT;
+    INSERT INTO test3 (y) VALUES (1);
+    COMMIT;
+    INSERT INTO test3 (y) VALUES (1);
+    INSERT INTO test3 (y) VALUES (2);
+    COMMIT;
+    INSERT INTO test3 (y) VALUES (3);  -- won't get here
+END;
+$$;
+
+SELECT * FROM test3;
+
+
+DROP TABLE test1;
+DROP TABLE test2;
+DROP TABLE test3;
diff --git a/src/pl/plpython/Makefile b/src/pl/plpython/Makefile
index cc91afebde7..d09910835d1 100644
--- a/src/pl/plpython/Makefile
+++ b/src/pl/plpython/Makefile
@@ -90,6 +90,7 @@ REGRESS = \
 	plpython_quote \
 	plpython_composite \
 	plpython_subtransaction \
+	plpython_transaction \
 	plpython_drop
 
 REGRESS_PLPYTHON3_MANGLE := $(REGRESS)
diff --git a/src/pl/plpython/expected/plpython_test.out b/src/pl/plpython/expected/plpython_test.out
index 847e4cc412e..39b994f4468 100644
--- a/src/pl/plpython/expected/plpython_test.out
+++ b/src/pl/plpython/expected/plpython_test.out
@@ -48,6 +48,7 @@ select module_contents();
  Error
  Fatal
  SPIError
+ commit
  cursor
  debug
  error
@@ -60,10 +61,11 @@ select module_contents();
  quote_ident
  quote_literal
  quote_nullable
+ rollback
  spiexceptions
  subtransaction
  warning
-(18 rows)
+(20 rows)
 
 CREATE FUNCTION elog_test_basic() RETURNS void
 AS $$
diff --git a/src/pl/plpython/expected/plpython_transaction.out b/src/pl/plpython/expected/plpython_transaction.out
new file mode 100644
index 00000000000..1fadc69b636
--- /dev/null
+++ b/src/pl/plpython/expected/plpython_transaction.out
@@ -0,0 +1,135 @@
+CREATE TABLE test1 (a int, b text);
+CREATE PROCEDURE transaction_test1()
+LANGUAGE plpythonu
+AS $$
+for i in range(0, 10):
+    plpy.execute("INSERT INTO test1 (a) VALUES (%d)" % i)
+    if i % 2 == 0:
+        plpy.commit()
+    else:
+        plpy.rollback()
+$$;
+CALL transaction_test1();
+SELECT * FROM test1;
+ a | b 
+---+---
+ 0 | 
+ 2 | 
+ 4 | 
+ 6 | 
+ 8 | 
+(5 rows)
+
+TRUNCATE test1;
+DO
+LANGUAGE plpythonu
+$$
+for i in range(0, 10):
+    plpy.execute("INSERT INTO test1 (a) VALUES (%d)" % i)
+    if i % 2 == 0:
+        plpy.commit()
+    else:
+        plpy.rollback()
+$$;
+SELECT * FROM test1;
+ a | b 
+---+---
+ 0 | 
+ 2 | 
+ 4 | 
+ 6 | 
+ 8 | 
+(5 rows)
+
+TRUNCATE test1;
+-- not allowed in a function
+CREATE FUNCTION transaction_test2() RETURNS int
+LANGUAGE plpythonu
+AS $$
+for i in range(0, 10):
+    plpy.execute("INSERT INTO test1 (a) VALUES (%d)" % i)
+    if i % 2 == 0:
+        plpy.commit()
+    else:
+        plpy.rollback()
+return 1
+$$;
+SELECT transaction_test2();
+ERROR:  invalid transaction termination
+CONTEXT:  PL/Python function "transaction_test2"
+SELECT * FROM test1;
+ a | b 
+---+---
+(0 rows)
+
+-- also not allowed if procedure is called from a function
+CREATE FUNCTION transaction_test3() RETURNS int
+LANGUAGE plpythonu
+AS $$
+plpy.execute("CALL transaction_test1()")
+return 1
+$$;
+SELECT transaction_test3();
+ERROR:  spiexceptions.InvalidTransactionTermination: invalid transaction termination
+CONTEXT:  Traceback (most recent call last):
+  PL/Python function "transaction_test3", line 2, in <module>
+    plpy.execute("CALL transaction_test1()")
+PL/Python function "transaction_test3"
+SELECT * FROM test1;
+ a | b 
+---+---
+(0 rows)
+
+-- DO block inside function
+CREATE FUNCTION transaction_test4() RETURNS int
+LANGUAGE plpythonu
+AS $$
+plpy.execute("DO LANGUAGE plpythonu $x$ plpy.commit() $x$")
+return 1
+$$;
+SELECT transaction_test4();
+ERROR:  spiexceptions.InvalidTransactionTermination: invalid transaction termination
+CONTEXT:  Traceback (most recent call last):
+  PL/Python function "transaction_test4", line 2, in <module>
+    plpy.execute("DO LANGUAGE plpythonu $x$ plpy.commit() $x$")
+PL/Python function "transaction_test4"
+-- commit inside subtransaction (prohibited)
+DO LANGUAGE plpythonu $$
+with plpy.subtransaction():
+    plpy.commit()
+$$;
+WARNING:  forcibly aborting a subtransaction that has not been exited
+ERROR:  cannot commit while a subtransaction is active
+CONTEXT:  PL/Python anonymous code block
+-- commit inside cursor loop
+CREATE TABLE test2 (x int);
+INSERT INTO test2 VALUES (0), (1), (2), (3), (4);
+TRUNCATE test1;
+DO LANGUAGE plpythonu $$
+for row in plpy.cursor("SELECT * FROM test2 ORDER BY x"):
+    plpy.execute("INSERT INTO test1 (a) VALUES (%s)" % row['x'])
+    plpy.commit()
+$$;
+ERROR:  cannot commit transaction while a cursor is open
+CONTEXT:  PL/Python anonymous code block
+SELECT * FROM test1;
+ a | b 
+---+---
+(0 rows)
+
+-- rollback inside cursor loop
+TRUNCATE test1;
+DO LANGUAGE plpythonu $$
+for row in plpy.cursor("SELECT * FROM test2 ORDER BY x"):
+    plpy.execute("INSERT INTO test1 (a) VALUES (%s)" % row['x'])
+    plpy.rollback()
+$$;
+ERROR:  cannot abort transaction while a cursor is open
+CONTEXT:  PL/Python anonymous code block
+SELECT * FROM test1;
+ a | b 
+---+---
+(0 rows)
+
+DROP TABLE test1;
+DROP TABLE test2;
diff --git a/src/pl/plpython/plpy_main.c b/src/pl/plpython/plpy_main.c
index 695de305838..5a197ce27ac 100644
--- a/src/pl/plpython/plpy_main.c
+++ b/src/pl/plpython/plpy_main.c
@@ -60,7 +60,7 @@ static void plpython_error_callback(void *arg);
 static void plpython_inline_error_callback(void *arg);
 static void PLy_init_interp(void);
 
-static PLyExecutionContext *PLy_push_execution_context(void);
+static PLyExecutionContext *PLy_push_execution_context(bool atomic_context);
 static void PLy_pop_execution_context(void);
 
 /* static state for Python library conflict detection */
@@ -219,14 +219,19 @@ plpython2_validator(PG_FUNCTION_ARGS)
 Datum
 plpython_call_handler(PG_FUNCTION_ARGS)
 {
+	bool		nonatomic;
 	Datum		retval;
 	PLyExecutionContext *exec_ctx;
 	ErrorContextCallback plerrcontext;
 
 	PLy_initialize();
 
+	nonatomic = fcinfo->context &&
+		IsA(fcinfo->context, CallContext) &&
+		!castNode(CallContext, fcinfo->context)->atomic;
+
 	/* Note: SPI_finish() happens in plpy_exec.c, which is dubious design */
-	if (SPI_connect() != SPI_OK_CONNECT)
+	if (SPI_connect_ext(nonatomic ? SPI_OPT_NONATOMIC : 0) != SPI_OK_CONNECT)
 		elog(ERROR, "SPI_connect failed");
 
 	/*
@@ -235,7 +240,7 @@ plpython_call_handler(PG_FUNCTION_ARGS)
 	 * here and the PG_TRY.  (plpython_error_callback expects the stack entry
 	 * to be there, so we have to make the context first.)
 	 */
-	exec_ctx = PLy_push_execution_context();
+	exec_ctx = PLy_push_execution_context(!nonatomic);
 
 	/*
 	 * Setup error traceback support for ereport()
@@ -303,7 +308,7 @@ plpython_inline_handler(PG_FUNCTION_ARGS)
 	PLy_initialize();
 
 	/* Note: SPI_finish() happens in plpy_exec.c, which is dubious design */
-	if (SPI_connect() != SPI_OK_CONNECT)
+	if (SPI_connect_ext(codeblock->atomic ? 0 : SPI_OPT_NONATOMIC) != SPI_OK_CONNECT)
 		elog(ERROR, "SPI_connect failed");
 
 	MemSet(&fake_fcinfo, 0, sizeof(fake_fcinfo));
@@ -332,7 +337,7 @@ plpython_inline_handler(PG_FUNCTION_ARGS)
 	 * need the stack entry, but for consistency with plpython_call_handler we
 	 * do it in this order.)
 	 */
-	exec_ctx = PLy_push_execution_context();
+	exec_ctx = PLy_push_execution_context(codeblock->atomic);
 
 	/*
 	 * Setup error traceback support for ereport()
@@ -430,12 +435,14 @@ PLy_get_scratch_context(PLyExecutionContext *context)
 }
 
 static PLyExecutionContext *
-PLy_push_execution_context(void)
+PLy_push_execution_context(bool atomic_context)
 {
 	PLyExecutionContext *context;
 
+	/* Pick a memory context similar to what SPI uses. */
 	context = (PLyExecutionContext *)
-		MemoryContextAlloc(TopTransactionContext, sizeof(PLyExecutionContext));
+		MemoryContextAlloc(atomic_context ? TopTransactionContext : PortalContext,
+						   sizeof(PLyExecutionContext));
 	context->curr_proc = NULL;
 	context->scratch_ctx = NULL;
 	context->next = PLy_execution_contexts;
diff --git a/src/pl/plpython/plpy_plpymodule.c b/src/pl/plpython/plpy_plpymodule.c
index 23f99e20ca3..3d7dd13f0cf 100644
--- a/src/pl/plpython/plpy_plpymodule.c
+++ b/src/pl/plpython/plpy_plpymodule.c
@@ -6,8 +6,10 @@
 
 #include "postgres.h"
 
+#include "access/xact.h"
 #include "mb/pg_wchar.h"
 #include "utils/builtins.h"
+#include "utils/snapmgr.h"
 
 #include "plpython.h"
 
@@ -15,6 +17,7 @@
 
 #include "plpy_cursorobject.h"
 #include "plpy_elog.h"
+#include "plpy_main.h"
 #include "plpy_planobject.h"
 #include "plpy_resultobject.h"
 #include "plpy_spi.h"
@@ -41,6 +44,8 @@ static PyObject *PLy_fatal(PyObject *self, PyObject *args, PyObject *kw);
 static PyObject *PLy_quote_literal(PyObject *self, PyObject *args);
 static PyObject *PLy_quote_nullable(PyObject *self, PyObject *args);
 static PyObject *PLy_quote_ident(PyObject *self, PyObject *args);
+static PyObject *PLy_commit(PyObject *self, PyObject *args);
+static PyObject *PLy_rollback(PyObject *self, PyObject *args);
 
 
 /* A list of all known exceptions, generated from backend/utils/errcodes.txt */
@@ -95,6 +100,12 @@ static PyMethodDef PLy_methods[] = {
 	 */
 	{"cursor", PLy_cursor, METH_VARARGS, NULL},
 
+	/*
+	 * transaction control
+	 */
+	{"commit", PLy_commit, METH_NOARGS, NULL},
+	{"rollback", PLy_rollback, METH_NOARGS, NULL},
+
 	{NULL, NULL, 0, NULL}
 };
 
@@ -577,3 +588,41 @@ PLy_output(volatile int level, PyObject *self, PyObject *args, PyObject *kw)
 	 */
 	Py_RETURN_NONE;
 }
+
+static PyObject *
+PLy_commit(PyObject *self, PyObject *args)
+{
+	PLyExecutionContext *exec_ctx = PLy_current_execution_context();
+
+	if (ThereArePinnedPortals())
+	   ereport(ERROR,
+			   (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+				errmsg("cannot commit transaction while a cursor is open")));
+
+	SPI_commit();
+	SPI_start_transaction();
+
+	/* was cleared at transaction end, reset pointer */
+	exec_ctx->scratch_ctx = NULL;
+
+	Py_RETURN_NONE;
+}
+
+static PyObject *
+PLy_rollback(PyObject *self, PyObject *args)
+{
+	PLyExecutionContext *exec_ctx = PLy_current_execution_context();
+
+	if (ThereArePinnedPortals())
+	   ereport(ERROR,
+			   (errcode(ERRCODE_INVALID_TRANSACTION_TERMINATION),
+				errmsg("cannot abort transaction while a cursor is open")));
+
+	SPI_rollback();
+	SPI_start_transaction();
+
+	/* was cleared at transaction end, reset pointer */
+	exec_ctx->scratch_ctx = NULL;
+
+	Py_RETURN_NONE;
+}
diff --git a/src/pl/plpython/sql/plpython_transaction.sql b/src/pl/plpython/sql/plpython_transaction.sql
new file mode 100644
index 00000000000..36c7b2ef385
--- /dev/null
+++ b/src/pl/plpython/sql/plpython_transaction.sql
@@ -0,0 +1,115 @@
+CREATE TABLE test1 (a int, b text);
+
+
+CREATE PROCEDURE transaction_test1()
+LANGUAGE plpythonu
+AS $$
+for i in range(0, 10):
+    plpy.execute("INSERT INTO test1 (a) VALUES (%d)" % i)
+    if i % 2 == 0:
+        plpy.commit()
+    else:
+        plpy.rollback()
+$$;
+
+CALL transaction_test1();
+
+SELECT * FROM test1;
+
+
+TRUNCATE test1;
+
+DO
+LANGUAGE plpythonu
+$$
+for i in range(0, 10):
+    plpy.execute("INSERT INTO test1 (a) VALUES (%d)" % i)
+    if i % 2 == 0:
+        plpy.commit()
+    else:
+        plpy.rollback()
+$$;
+
+SELECT * FROM test1;
+
+
+TRUNCATE test1;
+
+-- not allowed in a function
+CREATE FUNCTION transaction_test2() RETURNS int
+LANGUAGE plpythonu
+AS $$
+for i in range(0, 10):
+    plpy.execute("INSERT INTO test1 (a) VALUES (%d)" % i)
+    if i % 2 == 0:
+        plpy.commit()
+    else:
+        plpy.rollback()
+return 1
+$$;
+
+SELECT transaction_test2();
+
+SELECT * FROM test1;
+
+
+-- also not allowed if procedure is called from a function
+CREATE FUNCTION transaction_test3() RETURNS int
+LANGUAGE plpythonu
+AS $$
+plpy.execute("CALL transaction_test1()")
+return 1
+$$;
+
+SELECT transaction_test3();
+
+SELECT * FROM test1;
+
+
+-- DO block inside function
+CREATE FUNCTION transaction_test4() RETURNS int
+LANGUAGE plpythonu
+AS $$
+plpy.execute("DO LANGUAGE plpythonu $x$ plpy.commit() $x$")
+return 1
+$$;
+
+SELECT transaction_test4();
+
+
+-- commit inside subtransaction (prohibited)
+DO LANGUAGE plpythonu $$
+with plpy.subtransaction():
+    plpy.commit()
+$$;
+
+
+-- commit inside cursor loop
+CREATE TABLE test2 (x int);
+INSERT INTO test2 VALUES (0), (1), (2), (3), (4);
+
+TRUNCATE test1;
+
+DO LANGUAGE plpythonu $$
+for row in plpy.cursor("SELECT * FROM test2 ORDER BY x"):
+    plpy.execute("INSERT INTO test1 (a) VALUES (%s)" % row['x'])
+    plpy.commit()
+$$;
+
+SELECT * FROM test1;
+
+
+-- rollback inside cursor loop
+TRUNCATE test1;
+
+DO LANGUAGE plpythonu $$
+for row in plpy.cursor("SELECT * FROM test2 ORDER BY x"):
+    plpy.execute("INSERT INTO test1 (a) VALUES (%s)" % row['x'])
+    plpy.rollback()
+$$;
+
+SELECT * FROM test1;
+
+
+DROP TABLE test1;
+DROP TABLE test2;
diff --git a/src/pl/tcl/Makefile b/src/pl/tcl/Makefile
index 6a92a9b6aa7..ef61ee596e0 100644
--- a/src/pl/tcl/Makefile
+++ b/src/pl/tcl/Makefile
@@ -28,7 +28,7 @@ DATA = pltcl.control pltcl--1.0.sql pltcl--unpackaged--1.0.sql \
        pltclu.control pltclu--1.0.sql pltclu--unpackaged--1.0.sql
 
 REGRESS_OPTS = --dbname=$(PL_TESTDB) --load-extension=pltcl
-REGRESS = pltcl_setup pltcl_queries pltcl_call pltcl_start_proc pltcl_subxact pltcl_unicode
+REGRESS = pltcl_setup pltcl_queries pltcl_call pltcl_start_proc pltcl_subxact pltcl_unicode pltcl_transaction
 
 # Tcl on win32 ships with import libraries only for Microsoft Visual C++,
 # which are not compatible with mingw gcc. Therefore we need to build a
diff --git a/src/pl/tcl/expected/pltcl_transaction.out b/src/pl/tcl/expected/pltcl_transaction.out
new file mode 100644
index 00000000000..007204b99ad
--- /dev/null
+++ b/src/pl/tcl/expected/pltcl_transaction.out
@@ -0,0 +1,100 @@
+-- suppress CONTEXT so that function OIDs aren't in output
+\set VERBOSITY terse
+CREATE TABLE test1 (a int, b text);
+CREATE PROCEDURE transaction_test1()
+LANGUAGE pltcl
+AS $$
+for {set i 0} {$i < 10} {incr i} {
+    spi_exec "INSERT INTO test1 (a) VALUES ($i)"
+    if {$i % 2 == 0} {
+        commit
+    } else {
+        rollback
+    }
+}
+$$;
+CALL transaction_test1();
+SELECT * FROM test1;
+ a | b 
+---+---
+ 0 | 
+ 2 | 
+ 4 | 
+ 6 | 
+ 8 | 
+(5 rows)
+
+TRUNCATE test1;
+-- not allowed in a function
+CREATE FUNCTION transaction_test2() RETURNS int
+LANGUAGE pltcl
+AS $$
+for {set i 0} {$i < 10} {incr i} {
+    spi_exec "INSERT INTO test1 (a) VALUES ($i)"
+    if {$i % 2 == 0} {
+        commit
+    } else {
+        rollback
+    }
+}
+return 1
+$$;
+SELECT transaction_test2();
+ERROR:  invalid transaction termination
+SELECT * FROM test1;
+ a | b 
+---+---
+(0 rows)
+
+-- also not allowed if procedure is called from a function
+CREATE FUNCTION transaction_test3() RETURNS int
+LANGUAGE pltcl
+AS $$
+spi_exec "CALL transaction_test1()"
+return 1
+$$;
+SELECT transaction_test3();
+ERROR:  invalid transaction termination
+SELECT * FROM test1;
+ a | b 
+---+---
+(0 rows)
+
+-- commit inside cursor loop
+CREATE TABLE test2 (x int);
+INSERT INTO test2 VALUES (0), (1), (2), (3), (4);
+TRUNCATE test1;
+CREATE PROCEDURE transaction_test4a()
+LANGUAGE pltcl
+AS $$
+spi_exec -array row "SELECT * FROM test2 ORDER BY x" {
+    spi_exec "INSERT INTO test1 (a) VALUES ($row(x))"
+    commit
+}
+$$;
+CALL transaction_test4a();
+ERROR:  cannot commit while a subtransaction is active
+SELECT * FROM test1;
+ a | b 
+---+---
+(0 rows)
+
+-- rollback inside cursor loop
+TRUNCATE test1;
+CREATE PROCEDURE transaction_test4b()
+LANGUAGE pltcl
+AS $$
+spi_exec -array row "SELECT * FROM test2 ORDER BY x" {
+    spi_exec "INSERT INTO test1 (a) VALUES ($row(x))"
+    rollback
+}
+$$;
+CALL transaction_test4b();
+ERROR:  cannot roll back while a subtransaction is active
+SELECT * FROM test1;
+ a | b 
+---+---
+(0 rows)
+
+DROP TABLE test1;
+DROP TABLE test2;
diff --git a/src/pl/tcl/pltcl.c b/src/pl/tcl/pltcl.c
index 8f5847c4ff2..5df4dfdf552 100644
--- a/src/pl/tcl/pltcl.c
+++ b/src/pl/tcl/pltcl.c
@@ -312,6 +312,10 @@ static int pltcl_SPI_lastoid(ClientData cdata, Tcl_Interp *interp,
 				  int objc, Tcl_Obj *const objv[]);
 static int pltcl_subtransaction(ClientData cdata, Tcl_Interp *interp,
 					 int objc, Tcl_Obj *const objv[]);
+static int pltcl_commit(ClientData cdata, Tcl_Interp *interp,
+					 int objc, Tcl_Obj *const objv[]);
+static int pltcl_rollback(ClientData cdata, Tcl_Interp *interp,
+					 int objc, Tcl_Obj *const objv[]);
 
 static void pltcl_subtrans_begin(MemoryContext oldcontext,
 					 ResourceOwner oldowner);
@@ -524,6 +528,10 @@ pltcl_init_interp(pltcl_interp_desc *interp_desc, Oid prolang, bool pltrusted)
 						 pltcl_SPI_lastoid, NULL, NULL);
 	Tcl_CreateObjCommand(interp, "subtransaction",
 						 pltcl_subtransaction, NULL, NULL);
+	Tcl_CreateObjCommand(interp, "commit",
+						 pltcl_commit, NULL, NULL);
+	Tcl_CreateObjCommand(interp, "rollback",
+						 pltcl_rollback, NULL, NULL);
 
 	/************************************************************
 	 * Call the appropriate start_proc, if there is one.
@@ -797,6 +805,7 @@ static Datum
 pltcl_func_handler(PG_FUNCTION_ARGS, pltcl_call_state *call_state,
 				   bool pltrusted)
 {
+	bool		nonatomic;
 	pltcl_proc_desc *prodesc;
 	Tcl_Interp *volatile interp;
 	Tcl_Obj    *tcl_cmd;
@@ -804,8 +813,12 @@ pltcl_func_handler(PG_FUNCTION_ARGS, pltcl_call_state *call_state,
 	int			tcl_rc;
 	Datum		retval;
 
+	nonatomic = fcinfo->context &&
+		IsA(fcinfo->context, CallContext) &&
+		!castNode(CallContext, fcinfo->context)->atomic;
+
 	/* Connect to SPI manager */
-	if (SPI_connect() != SPI_OK_CONNECT)
+	if (SPI_connect_ext(nonatomic ? SPI_OPT_NONATOMIC : 0) != SPI_OK_CONNECT)
 		elog(ERROR, "could not connect to SPI manager");
 
 	/* Find or compile the function */
@@ -2937,6 +2950,86 @@ pltcl_subtransaction(ClientData cdata, Tcl_Interp *interp,
 
 
 /**********************************************************************
+ * pltcl_commit()
+ *
+ * Commit the transaction and start a new one.
+ **********************************************************************/
+static int
+pltcl_commit(ClientData cdata, Tcl_Interp *interp,
+			 int objc, Tcl_Obj *const objv[])
+{
+	MemoryContext oldcontext = CurrentMemoryContext;
+
+	PG_TRY();
+	{
+		SPI_commit();
+		SPI_start_transaction();
+	}
+	PG_CATCH();
+	{
+		ErrorData  *edata;
+
+		/* Save error info */
+		MemoryContextSwitchTo(oldcontext);
+		edata = CopyErrorData();
+		FlushErrorState();
+
+		/* Pass the error data to Tcl */
+		pltcl_construct_errorCode(interp, edata);
+		UTF_BEGIN;
+		Tcl_SetObjResult(interp, Tcl_NewStringObj(UTF_E2U(edata->message), -1));
+		UTF_END;
+		FreeErrorData(edata);
+
+		return TCL_ERROR;
+	}
+	PG_END_TRY();
+
+	return TCL_OK;
+}
+
+
+/**********************************************************************
+ * pltcl_rollback()
+ *
+ * Abort the transaction and start a new one.
+ **********************************************************************/
+static int
+pltcl_rollback(ClientData cdata, Tcl_Interp *interp,
+			   int objc, Tcl_Obj *const objv[])
+{
+	MemoryContext oldcontext = CurrentMemoryContext;
+
+	PG_TRY();
+	{
+		SPI_rollback();
+		SPI_start_transaction();
+	}
+	PG_CATCH();
+	{
+		ErrorData  *edata;
+
+		/* Save error info */
+		MemoryContextSwitchTo(oldcontext);
+		edata = CopyErrorData();
+		FlushErrorState();
+
+		/* Pass the error data to Tcl */
+		pltcl_construct_errorCode(interp, edata);
+		UTF_BEGIN;
+		Tcl_SetObjResult(interp, Tcl_NewStringObj(UTF_E2U(edata->message), -1));
+		UTF_END;
+		FreeErrorData(edata);
+
+		return TCL_ERROR;
+	}
+	PG_END_TRY();
+
+	return TCL_OK;
+}
+
+
+/**********************************************************************
  * pltcl_set_tuple_values() - Set variables for all attributes
  *				  of a given tuple
  *
diff --git a/src/pl/tcl/sql/pltcl_transaction.sql b/src/pl/tcl/sql/pltcl_transaction.sql
new file mode 100644
index 00000000000..c752faf6654
--- /dev/null
+++ b/src/pl/tcl/sql/pltcl_transaction.sql
@@ -0,0 +1,98 @@
+-- suppress CONTEXT so that function OIDs aren't in output
+\set VERBOSITY terse
+
+CREATE TABLE test1 (a int, b text);
+
+
+CREATE PROCEDURE transaction_test1()
+LANGUAGE pltcl
+AS $$
+for {set i 0} {$i < 10} {incr i} {
+    spi_exec "INSERT INTO test1 (a) VALUES ($i)"
+    if {$i % 2 == 0} {
+        commit
+    } else {
+        rollback
+    }
+}
+$$;
+
+CALL transaction_test1();
+
+SELECT * FROM test1;
+
+
+TRUNCATE test1;
+
+-- not allowed in a function
+CREATE FUNCTION transaction_test2() RETURNS int
+LANGUAGE pltcl
+AS $$
+for {set i 0} {$i < 10} {incr i} {
+    spi_exec "INSERT INTO test1 (a) VALUES ($i)"
+    if {$i % 2 == 0} {
+        commit
+    } else {
+        rollback
+    }
+}
+return 1
+$$;
+
+SELECT transaction_test2();
+
+SELECT * FROM test1;
+
+
+-- also not allowed if procedure is called from a function
+CREATE FUNCTION transaction_test3() RETURNS int
+LANGUAGE pltcl
+AS $$
+spi_exec "CALL transaction_test1()"
+return 1
+$$;
+
+SELECT transaction_test3();
+
+SELECT * FROM test1;
+
+
+-- commit inside cursor loop
+CREATE TABLE test2 (x int);
+INSERT INTO test2 VALUES (0), (1), (2), (3), (4);
+
+TRUNCATE test1;
+
+CREATE PROCEDURE transaction_test4a()
+LANGUAGE pltcl
+AS $$
+spi_exec -array row "SELECT * FROM test2 ORDER BY x" {
+    spi_exec "INSERT INTO test1 (a) VALUES ($row(x))"
+    commit
+}
+$$;
+
+CALL transaction_test4a();
+
+SELECT * FROM test1;
+
+
+-- rollback inside cursor loop
+TRUNCATE test1;
+
+CREATE PROCEDURE transaction_test4b()
+LANGUAGE pltcl
+AS $$
+spi_exec -array row "SELECT * FROM test2 ORDER BY x" {
+    spi_exec "INSERT INTO test1 (a) VALUES ($row(x))"
+    rollback
+}
+$$;
+
+CALL transaction_test4b();
+
+SELECT * FROM test1;
+
+
+DROP TABLE test1;
+DROP TABLE test2;