From 056a5a3f63f1a29d9266165ee6e25c6a51ddd63c Mon Sep 17 00:00:00 2001 From: Peter Eisentraut Date: Wed, 28 Mar 2018 18:57:10 -0400 Subject: [PATCH] Allow committing inside cursor loop Previously, committing or aborting inside a cursor loop was prohibited because that would close and remove the cursor. To allow that, automatically convert such cursors to holdable cursors so they survive commits or rollbacks. Portals now have a new state "auto-held", which means they have been converted automatically from pinned. An auto-held portal is kept on transaction commit or rollback, but is still removed when returning to the main loop on error. This supports all languages that have cursor loop constructs: PL/pgSQL, PL/Python, PL/Perl. Reviewed-by: Ildus Kurbangaliev --- doc/src/sgml/plperl.sgml | 5 - doc/src/sgml/plpgsql.sgml | 37 ++++- doc/src/sgml/plpython.sgml | 4 +- src/backend/tcop/postgres.c | 2 + src/backend/utils/mmgr/portalmem.c | 138 +++++++++++++----- src/include/utils/portal.h | 5 +- src/pl/plperl/expected/plperl_transaction.out | 71 ++++++++- src/pl/plperl/plperl.c | 10 +- src/pl/plperl/sql/plperl_transaction.sql | 43 ++++++ .../src/expected/plpgsql_transaction.out | 108 +++++++++++++- src/pl/plpgsql/src/pl_exec.c | 18 +-- .../plpgsql/src/sql/plpgsql_transaction.sql | 67 +++++++++ .../expected/plpython_transaction.out | 67 ++++++++- src/pl/plpython/plpy_plpymodule.c | 10 +- src/pl/plpython/sql/plpython_transaction.sql | 36 +++++ 15 files changed, 534 insertions(+), 87 deletions(-) diff --git a/doc/src/sgml/plperl.sgml b/doc/src/sgml/plperl.sgml index 518a86459a..82f56cb8ab 100644 --- a/doc/src/sgml/plperl.sgml +++ b/doc/src/sgml/plperl.sgml @@ -722,11 +722,6 @@ $$; CALL transaction_test1(); - - - Transactions cannot be ended when a cursor created by - spi_query is open. - diff --git a/doc/src/sgml/plpgsql.sgml b/doc/src/sgml/plpgsql.sgml index b63b8496c7..5b2aac618e 100644 --- a/doc/src/sgml/plpgsql.sgml +++ b/doc/src/sgml/plpgsql.sgml @@ -3510,8 +3510,41 @@ CALL transaction_test1(); - A transaction cannot be ended inside a loop over a query result, nor - inside a block with exception handlers. + Special considerations apply to cursor loops. Consider this example: + +CREATE PROCEDURE transaction_test2() +LANGUAGE plpgsql +AS $$ +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; +$$; + +CALL transaction_test2(); + + Normally, cursors are automatically closed at transaction commit. + However, a cursor created as part of a loop like this is automatically + converted to a holdable cursor by the first COMMIT or + ROLLBACK. That means that the cursor is fully + evaluated at the first COMMIT or + ROLLBACK rather than row by row. The cursor is still + removed automatically after the loop, so this is mostly invisible to the + user. + + + + Transaction commands are not allowed in cursor loops driven by commands + that are not read-only (for example UPDATE + ... RETURNING). + + + + A transaction cannot be ended inside a block with exception handlers. diff --git a/doc/src/sgml/plpython.sgml b/doc/src/sgml/plpython.sgml index 3b7974690e..de38327242 100644 --- a/doc/src/sgml/plpython.sgml +++ b/doc/src/sgml/plpython.sgml @@ -1416,9 +1416,7 @@ CALL transaction_test1(); - Transactions cannot be ended when a cursor created by - plpy.cursor is open or when an explicit subtransaction - is active. + Transactions cannot be ended when an explicit subtransaction is active. diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c index f7aa4a7484..6fc1cc272b 100644 --- a/src/backend/tcop/postgres.c +++ b/src/backend/tcop/postgres.c @@ -3938,6 +3938,8 @@ PostgresMain(int argc, char *argv[], if (am_walsender) WalSndErrorCleanup(); + PortalErrorCleanup(); + /* * We can't release replication slots inside AbortTransaction() as we * need to be able to start and abort transactions while having a slot diff --git a/src/backend/utils/mmgr/portalmem.c b/src/backend/utils/mmgr/portalmem.c index 75a6dde32b..4307f5cc70 100644 --- a/src/backend/utils/mmgr/portalmem.c +++ b/src/backend/utils/mmgr/portalmem.c @@ -620,6 +620,36 @@ PortalHashTableDeleteAll(void) } } +/* + * "Hold" a portal. Prepare it for access by later transactions. + */ +static void +HoldPortal(Portal portal) +{ + /* + * Note that PersistHoldablePortal() must release all resources + * used by the portal that are local to the creating transaction. + */ + PortalCreateHoldStore(portal); + PersistHoldablePortal(portal); + + /* drop cached plan reference, if any */ + PortalReleaseCachedPlan(portal); + + /* + * Any resources belonging to the portal will be released in the + * upcoming transaction-wide cleanup; the portal will no longer + * have its own resources. + */ + portal->resowner = NULL; + + /* + * Having successfully exported the holdable cursor, mark it as + * not belonging to this transaction. + */ + portal->createSubid = InvalidSubTransactionId; + portal->activeSubid = InvalidSubTransactionId; +} /* * Pre-commit processing for portals. @@ -648,9 +678,10 @@ PreCommit_Portals(bool isPrepare) /* * There should be no pinned portals anymore. Complain if someone - * leaked one. + * leaked one. Auto-held portals are allowed; we assume that whoever + * pinned them is managing them. */ - if (portal->portalPinned) + if (portal->portalPinned && !portal->autoHeld) elog(ERROR, "cannot commit while a portal is pinned"); /* @@ -684,29 +715,7 @@ PreCommit_Portals(bool isPrepare) (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), errmsg("cannot PREPARE a transaction that has created a cursor WITH HOLD"))); - /* - * Note that PersistHoldablePortal() must release all resources - * used by the portal that are local to the creating transaction. - */ - PortalCreateHoldStore(portal); - PersistHoldablePortal(portal); - - /* drop cached plan reference, if any */ - PortalReleaseCachedPlan(portal); - - /* - * Any resources belonging to the portal will be released in the - * upcoming transaction-wide cleanup; the portal will no longer - * have its own resources. - */ - portal->resowner = NULL; - - /* - * Having successfully exported the holdable cursor, mark it as - * not belonging to this transaction. - */ - portal->createSubid = InvalidSubTransactionId; - portal->activeSubid = InvalidSubTransactionId; + HoldPortal(portal); /* Report we changed state */ result = true; @@ -771,6 +780,14 @@ AtAbort_Portals(void) if (portal->createSubid == InvalidSubTransactionId) continue; + /* + * Do nothing to auto-held cursors. This is similar to the case of a + * cursor from a previous transaction, but it could also be that the + * cursor was auto-held in this transaction, so it wants to live on. + */ + if (portal->autoHeld) + continue; + /* * If it was created in the current transaction, we can't do normal * shutdown on a READY portal either; it might refer to objects @@ -834,8 +851,11 @@ AtCleanup_Portals(void) if (portal->status == PORTAL_ACTIVE) continue; - /* Do nothing to cursors held over from a previous transaction */ - if (portal->createSubid == InvalidSubTransactionId) + /* + * Do nothing to cursors held over from a previous transaction or + * auto-held ones. + */ + if (portal->createSubid == InvalidSubTransactionId || portal->autoHeld) { Assert(portal->status != PORTAL_ACTIVE); Assert(portal->resowner == NULL); @@ -865,6 +885,32 @@ AtCleanup_Portals(void) } } +/* + * Portal-related cleanup when we return to the main loop on error. + * + * This is different from the cleanup at transaction abort. Auto-held portals + * are cleaned up on error but not on transaction abort. + */ +void +PortalErrorCleanup(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->autoHeld) + { + portal->portalPinned = false; + PortalDrop(portal, false); + } + } +} + /* * Pre-subcommit processing for portals. * @@ -1164,8 +1210,19 @@ ThereAreNoReadyPortals(void) return true; } -bool -ThereArePinnedPortals(void) +/* + * Hold all pinned portals. + * + * A procedural language implementation that uses pinned portals for its + * internally generated cursors can call this in its COMMIT command to convert + * those cursors to held cursors, so that they survive the transaction end. + * We mark those portals as "auto-held" so that exception exit knows to clean + * them up. (In normal, non-exception code paths, the PL needs to clean those + * portals itself, since transaction end won't do it anymore, but that should + * be normal practice anyway.) + */ +void +HoldPinnedPortals(void) { HASH_SEQ_STATUS status; PortalHashEnt *hentry; @@ -1176,9 +1233,24 @@ ThereArePinnedPortals(void) { Portal portal = hentry->portal; - if (portal->portalPinned) - return true; - } + if (portal->portalPinned && !portal->autoHeld) + { + /* + * Doing transaction control, especially abort, inside a cursor + * loop that is not read-only, for example using UPDATE + * ... RETURNING, has weird semantics issues. Also, this + * implementation wouldn't work, because such portals cannot be + * held. (The core grammar enforces that only SELECT statements + * can drive a cursor, but for example PL/pgSQL does not restrict + * it.) + */ + if (portal->strategy != PORTAL_ONE_SELECT) + ereport(ERROR, + (errcode(ERRCODE_INVALID_TRANSACTION_TERMINATION), + errmsg("cannot perform transaction commands inside a cursor loop that is not read-only"))); - return false; + portal->autoHeld = true; + HoldPortal(portal); + } + } } diff --git a/src/include/utils/portal.h b/src/include/utils/portal.h index b903cb0fbe..b4a259dcf8 100644 --- a/src/include/utils/portal.h +++ b/src/include/utils/portal.h @@ -147,6 +147,8 @@ typedef struct PortalData /* Status data */ PortalStatus status; /* see above */ bool portalPinned; /* a pinned portal can't be dropped */ + bool autoHeld; /* was automatically converted from pinned to + * held (see HoldPinnedPortals()) */ /* If not NULL, Executor is active; call ExecutorEnd eventually: */ QueryDesc *queryDesc; /* info needed for executor invocation */ @@ -204,6 +206,7 @@ extern void EnablePortalManager(void); extern bool PreCommit_Portals(bool isPrepare); extern void AtAbort_Portals(void); extern void AtCleanup_Portals(void); +extern void PortalErrorCleanup(void); extern void AtSubCommit_Portals(SubTransactionId mySubid, SubTransactionId parentSubid, ResourceOwner parentXactOwner); @@ -231,6 +234,6 @@ extern PlannedStmt *PortalGetPrimaryStmt(Portal portal); extern void PortalCreateHoldStore(Portal portal); extern void PortalHashTableDeleteAll(void); extern bool ThereAreNoReadyPortals(void); -extern bool ThereArePinnedPortals(void); +extern void HoldPinnedPortals(void); #endif /* PORTAL_H */ diff --git a/src/pl/plperl/expected/plperl_transaction.out b/src/pl/plperl/expected/plperl_transaction.out index bd7b7f8660..7ca0ef35fb 100644 --- a/src/pl/plperl/expected/plperl_transaction.out +++ b/src/pl/plperl/expected/plperl_transaction.out @@ -105,11 +105,44 @@ while (defined($row = spi_fetchrow($sth))) { 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 | + 1 | + 2 | + 3 | + 4 | +(5 rows) + +-- check that this doesn't leak a holdable portal +SELECT * FROM pg_cursors; + name | statement | is_holdable | is_binary | is_scrollable | creation_time +------+-----------+-------------+-----------+---------------+--------------- +(0 rows) + +-- error in cursor loop with commit +TRUNCATE test1; +DO LANGUAGE plperl $$ +my $sth = spi_query("SELECT * FROM test2 ORDER BY x"); +my $row; +while (defined($row = spi_fetchrow($sth))) { + spi_exec_query("INSERT INTO test1 (a) VALUES (12/(" . $row->{x} . "-2))"); + spi_commit(); +} +$$; +ERROR: division by zero at line 5. +CONTEXT: PL/Perl anonymous code block +SELECT * FROM test1; + a | b +-----+--- + -6 | + -12 | +(2 rows) + +SELECT * FROM pg_cursors; + name | statement | is_holdable | is_binary | is_scrollable | creation_time +------+-----------+-------------+-----------+---------------+--------------- (0 rows) -- rollback inside cursor loop @@ -122,12 +155,42 @@ while (defined($row = spi_fetchrow($sth))) { spi_rollback(); } $$; -ERROR: cannot abort transaction while a cursor is open at line 6. -CONTEXT: PL/Perl anonymous code block SELECT * FROM test1; a | b ---+--- (0 rows) +SELECT * FROM pg_cursors; + name | statement | is_holdable | is_binary | is_scrollable | creation_time +------+-----------+-------------+-----------+---------------+--------------- +(0 rows) + +-- first commit then rollback inside cursor loop +TRUNCATE test1; +DO LANGUAGE plperl $$ +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 (" . $row->{x} . ")"); + if ($row->{x} % 2 == 0) { + spi_commit(); + } else { + spi_rollback(); + } +} +$$; +SELECT * FROM test1; + a | b +---+--- + 0 | + 2 | + 4 | +(3 rows) + +SELECT * FROM pg_cursors; + name | statement | is_holdable | is_binary | is_scrollable | creation_time +------+-----------+-------------+-----------+---------------+--------------- +(0 rows) + DROP TABLE test1; DROP TABLE test2; diff --git a/src/pl/plperl/plperl.c b/src/pl/plperl/plperl.c index 7c0d665549..a7dd8367bb 100644 --- a/src/pl/plperl/plperl.c +++ b/src/pl/plperl/plperl.c @@ -3965,10 +3965,7 @@ plperl_spi_commit(void) PG_TRY(); { - if (ThereArePinnedPortals()) - ereport(ERROR, - (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), - errmsg("cannot commit transaction while a cursor is open"))); + HoldPinnedPortals(); SPI_commit(); SPI_start_transaction(); @@ -3995,10 +3992,7 @@ plperl_spi_rollback(void) PG_TRY(); { - if (ThereArePinnedPortals()) - ereport(ERROR, - (errcode(ERRCODE_INVALID_TRANSACTION_TERMINATION), - errmsg("cannot abort transaction while a cursor is open"))); + HoldPinnedPortals(); SPI_rollback(); SPI_start_transaction(); diff --git a/src/pl/plperl/sql/plperl_transaction.sql b/src/pl/plperl/sql/plperl_transaction.sql index 5c14d4732e..0a60799805 100644 --- a/src/pl/plperl/sql/plperl_transaction.sql +++ b/src/pl/plperl/sql/plperl_transaction.sql @@ -100,6 +100,26 @@ $$; SELECT * FROM test1; +-- check that this doesn't leak a holdable portal +SELECT * FROM pg_cursors; + + +-- error in cursor loop with commit +TRUNCATE test1; + +DO LANGUAGE plperl $$ +my $sth = spi_query("SELECT * FROM test2 ORDER BY x"); +my $row; +while (defined($row = spi_fetchrow($sth))) { + spi_exec_query("INSERT INTO test1 (a) VALUES (12/(" . $row->{x} . "-2))"); + spi_commit(); +} +$$; + +SELECT * FROM test1; + +SELECT * FROM pg_cursors; + -- rollback inside cursor loop TRUNCATE test1; @@ -115,6 +135,29 @@ $$; SELECT * FROM test1; +SELECT * FROM pg_cursors; + + +-- first commit then rollback inside cursor loop +TRUNCATE test1; + +DO LANGUAGE plperl $$ +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 (" . $row->{x} . ")"); + if ($row->{x} % 2 == 0) { + spi_commit(); + } else { + spi_rollback(); + } +} +$$; + +SELECT * FROM test1; + +SELECT * FROM pg_cursors; + DROP TABLE test1; DROP TABLE test2; diff --git a/src/pl/plpgsql/src/expected/plpgsql_transaction.out b/src/pl/plpgsql/src/expected/plpgsql_transaction.out index b601f6aef6..b7f77101c3 100644 --- a/src/pl/plpgsql/src/expected/plpgsql_transaction.out +++ b/src/pl/plpgsql/src/expected/plpgsql_transaction.out @@ -195,11 +195,47 @@ BEGIN END LOOP; END; $$; -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 | + 1 | + 2 | + 3 | + 4 | +(5 rows) + +-- check that this doesn't leak a holdable portal +SELECT * FROM pg_cursors; + name | statement | is_holdable | is_binary | is_scrollable | creation_time +------+-----------+-------------+-----------+---------------+--------------- +(0 rows) + +-- error in cursor loop with commit +TRUNCATE test1; +DO LANGUAGE plpgsql $$ +DECLARE + r RECORD; +BEGIN + FOR r IN SELECT * FROM test2 ORDER BY x LOOP + INSERT INTO test1 (a) VALUES (12/(r.x-2)); + COMMIT; + END LOOP; +END; +$$; +ERROR: division by zero +CONTEXT: SQL statement "INSERT INTO test1 (a) VALUES (12/(r.x-2))" +PL/pgSQL function inline_code_block line 6 at SQL statement +SELECT * FROM test1; + a | b +-----+--- + -6 | + -12 | +(2 rows) + +SELECT * FROM pg_cursors; + name | statement | is_holdable | is_binary | is_scrollable | creation_time +------+-----------+-------------+-----------+---------------+--------------- (0 rows) -- rollback inside cursor loop @@ -214,13 +250,79 @@ BEGIN END LOOP; END; $$; -ERROR: cannot abort transaction inside a cursor loop +SELECT * FROM test1; + a | b +---+--- +(0 rows) + +SELECT * FROM pg_cursors; + name | statement | is_holdable | is_binary | is_scrollable | creation_time +------+-----------+-------------+-----------+---------------+--------------- +(0 rows) + +-- first commit then rollback inside cursor loop +TRUNCATE test1; +DO LANGUAGE plpgsql $$ +DECLARE + r RECORD; +BEGIN + FOR r IN SELECT * FROM test2 ORDER BY x LOOP + INSERT INTO test1 (a) VALUES (r.x); + IF r.x % 2 = 0 THEN + COMMIT; + ELSE + ROLLBACK; + END IF; + END LOOP; +END; +$$; +SELECT * FROM test1; + a | b +---+--- + 0 | + 2 | + 4 | +(3 rows) + +SELECT * FROM pg_cursors; + name | statement | is_holdable | is_binary | is_scrollable | creation_time +------+-----------+-------------+-----------+---------------+--------------- +(0 rows) + +-- rollback inside cursor loop +TRUNCATE test1; +DO LANGUAGE plpgsql $$ +DECLARE + r RECORD; +BEGIN + FOR r IN UPDATE test2 SET x = x * 2 RETURNING x LOOP + INSERT INTO test1 (a) VALUES (r.x); + ROLLBACK; + END LOOP; +END; +$$; +ERROR: cannot perform transaction commands inside a cursor loop that is not read-only CONTEXT: PL/pgSQL function inline_code_block line 7 at ROLLBACK SELECT * FROM test1; a | b ---+--- (0 rows) +SELECT * FROM test2; + x +--- + 0 + 1 + 2 + 3 + 4 +(5 rows) + +SELECT * FROM pg_cursors; + name | statement | is_holdable | is_binary | is_scrollable | creation_time +------+-----------+-------------+-----------+---------------+--------------- +(0 rows) + -- commit inside block with exception handler TRUNCATE test1; DO LANGUAGE plpgsql $$ diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c index fc0f0f0480..f574aa77f0 100644 --- a/src/pl/plpgsql/src/pl_exec.c +++ b/src/pl/plpgsql/src/pl_exec.c @@ -4677,14 +4677,7 @@ exec_stmt_close(PLpgSQL_execstate *estate, PLpgSQL_stmt_close *stmt) 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"))); + HoldPinnedPortals(); SPI_commit(); SPI_start_transaction(); @@ -4703,14 +4696,7 @@ exec_stmt_commit(PLpgSQL_execstate *estate, PLpgSQL_stmt_commit *stmt) 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"))); + HoldPinnedPortals(); SPI_rollback(); SPI_start_transaction(); diff --git a/src/pl/plpgsql/src/sql/plpgsql_transaction.sql b/src/pl/plpgsql/src/sql/plpgsql_transaction.sql index a718f50f89..b7b6f81128 100644 --- a/src/pl/plpgsql/src/sql/plpgsql_transaction.sql +++ b/src/pl/plpgsql/src/sql/plpgsql_transaction.sql @@ -175,6 +175,28 @@ $$; SELECT * FROM test1; +-- check that this doesn't leak a holdable portal +SELECT * FROM pg_cursors; + + +-- error in cursor loop with commit +TRUNCATE test1; + +DO LANGUAGE plpgsql $$ +DECLARE + r RECORD; +BEGIN + FOR r IN SELECT * FROM test2 ORDER BY x LOOP + INSERT INTO test1 (a) VALUES (12/(r.x-2)); + COMMIT; + END LOOP; +END; +$$; + +SELECT * FROM test1; + +SELECT * FROM pg_cursors; + -- rollback inside cursor loop TRUNCATE test1; @@ -192,6 +214,51 @@ $$; SELECT * FROM test1; +SELECT * FROM pg_cursors; + + +-- first commit then rollback inside cursor loop +TRUNCATE test1; + +DO LANGUAGE plpgsql $$ +DECLARE + r RECORD; +BEGIN + FOR r IN SELECT * FROM test2 ORDER BY x LOOP + INSERT INTO test1 (a) VALUES (r.x); + IF r.x % 2 = 0 THEN + COMMIT; + ELSE + ROLLBACK; + END IF; + END LOOP; +END; +$$; + +SELECT * FROM test1; + +SELECT * FROM pg_cursors; + + +-- rollback inside cursor loop +TRUNCATE test1; + +DO LANGUAGE plpgsql $$ +DECLARE + r RECORD; +BEGIN + FOR r IN UPDATE test2 SET x = x * 2 RETURNING x LOOP + INSERT INTO test1 (a) VALUES (r.x); + ROLLBACK; + END LOOP; +END; +$$; + +SELECT * FROM test1; +SELECT * FROM test2; + +SELECT * FROM pg_cursors; + -- commit inside block with exception handler TRUNCATE test1; diff --git a/src/pl/plpython/expected/plpython_transaction.out b/src/pl/plpython/expected/plpython_transaction.out index 6f6dfadf9c..14152993c7 100644 --- a/src/pl/plpython/expected/plpython_transaction.out +++ b/src/pl/plpython/expected/plpython_transaction.out @@ -111,11 +111,44 @@ for row in plpy.cursor("SELECT * FROM test2 ORDER BY x"): plpy.execute("INSERT INTO test1 (a) VALUES (%s)" % row['x']) plpy.commit() $$; -ERROR: cannot commit transaction while a cursor is open -CONTEXT: PL/Python anonymous code block SELECT * FROM test1; a | b ---+--- + 0 | + 1 | + 2 | + 3 | + 4 | +(5 rows) + +-- check that this doesn't leak a holdable portal +SELECT * FROM pg_cursors; + name | statement | is_holdable | is_binary | is_scrollable | creation_time +------+-----------+-------------+-----------+---------------+--------------- +(0 rows) + +-- error in cursor loop with commit +TRUNCATE test1; +DO LANGUAGE plpythonu $$ +for row in plpy.cursor("SELECT * FROM test2 ORDER BY x"): + plpy.execute("INSERT INTO test1 (a) VALUES (12/(%s-2))" % row['x']) + plpy.commit() +$$; +ERROR: spiexceptions.DivisionByZero: division by zero +CONTEXT: Traceback (most recent call last): + PL/Python anonymous code block, line 3, in + plpy.execute("INSERT INTO test1 (a) VALUES (12/(%s-2))" % row['x']) +PL/Python anonymous code block +SELECT * FROM test1; + a | b +-----+--- + -6 | + -12 | +(2 rows) + +SELECT * FROM pg_cursors; + name | statement | is_holdable | is_binary | is_scrollable | creation_time +------+-----------+-------------+-----------+---------------+--------------- (0 rows) -- rollback inside cursor loop @@ -125,12 +158,38 @@ for row in plpy.cursor("SELECT * FROM test2 ORDER BY x"): plpy.execute("INSERT INTO test1 (a) VALUES (%s)" % row['x']) plpy.rollback() $$; -ERROR: cannot abort transaction while a cursor is open -CONTEXT: PL/Python anonymous code block SELECT * FROM test1; a | b ---+--- (0 rows) +SELECT * FROM pg_cursors; + name | statement | is_holdable | is_binary | is_scrollable | creation_time +------+-----------+-------------+-----------+---------------+--------------- +(0 rows) + +-- first commit then rollback inside cursor loop +TRUNCATE test1; +DO LANGUAGE plpythonu $$ +for row in plpy.cursor("SELECT * FROM test2 ORDER BY x"): + plpy.execute("INSERT INTO test1 (a) VALUES (%s)" % row['x']) + if row['x'] % 2 == 0: + plpy.commit() + else: + plpy.rollback() +$$; +SELECT * FROM test1; + a | b +---+--- + 0 | + 2 | + 4 | +(3 rows) + +SELECT * FROM pg_cursors; + name | statement | is_holdable | is_binary | is_scrollable | creation_time +------+-----------+-------------+-----------+---------------+--------------- +(0 rows) + DROP TABLE test1; DROP TABLE test2; diff --git a/src/pl/plpython/plpy_plpymodule.c b/src/pl/plpython/plpy_plpymodule.c index 3d7dd13f0c..c55cd959c2 100644 --- a/src/pl/plpython/plpy_plpymodule.c +++ b/src/pl/plpython/plpy_plpymodule.c @@ -594,10 +594,7 @@ 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"))); + HoldPinnedPortals(); SPI_commit(); SPI_start_transaction(); @@ -613,10 +610,7 @@ 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"))); + HoldPinnedPortals(); SPI_rollback(); SPI_start_transaction(); diff --git a/src/pl/plpython/sql/plpython_transaction.sql b/src/pl/plpython/sql/plpython_transaction.sql index b337d4e300..33b37e5b7f 100644 --- a/src/pl/plpython/sql/plpython_transaction.sql +++ b/src/pl/plpython/sql/plpython_transaction.sql @@ -99,6 +99,23 @@ $$; SELECT * FROM test1; +-- check that this doesn't leak a holdable portal +SELECT * FROM pg_cursors; + + +-- error in cursor loop with commit +TRUNCATE test1; + +DO LANGUAGE plpythonu $$ +for row in plpy.cursor("SELECT * FROM test2 ORDER BY x"): + plpy.execute("INSERT INTO test1 (a) VALUES (12/(%s-2))" % row['x']) + plpy.commit() +$$; + +SELECT * FROM test1; + +SELECT * FROM pg_cursors; + -- rollback inside cursor loop TRUNCATE test1; @@ -111,6 +128,25 @@ $$; SELECT * FROM test1; +SELECT * FROM pg_cursors; + + +-- first commit then rollback inside cursor loop +TRUNCATE test1; + +DO LANGUAGE plpythonu $$ +for row in plpy.cursor("SELECT * FROM test2 ORDER BY x"): + plpy.execute("INSERT INTO test1 (a) VALUES (%s)" % row['x']) + if row['x'] % 2 == 0: + plpy.commit() + else: + plpy.rollback() +$$; + +SELECT * FROM test1; + +SELECT * FROM pg_cursors; + DROP TABLE test1; DROP TABLE test2; -- 2.40.0