From 82ff0cc91d9840d1c56ca1beed58bedfde3da9a3 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Mon, 8 Oct 2018 16:16:36 -0400 Subject: [PATCH] Advance transaction timestamp for intra-procedure transactions. Per discussion, this behavior seems less astonishing than not doing so. Peter Eisentraut and Tom Lane Discussion: https://postgr.es/m/20180920234040.GC29981@momjian.us --- src/backend/access/transam/xact.c | 22 ++++++++----- src/backend/executor/spi.c | 13 ++++++++ src/include/executor/spi.h | 1 + .../src/expected/plpgsql_transaction.out | 30 +++++++++++++++++ .../plpgsql/src/sql/plpgsql_transaction.sql | 33 +++++++++++++++++++ 5 files changed, 91 insertions(+), 8 deletions(-) diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c index e3f668bf6a..59e021f887 100644 --- a/src/backend/access/transam/xact.c +++ b/src/backend/access/transam/xact.c @@ -1887,20 +1887,26 @@ StartTransaction(void) TRACE_POSTGRESQL_TRANSACTION_START(vxid.localTransactionId); /* - * set transaction_timestamp() (a/k/a now()). We want this to be the same - * as the first command's statement_timestamp(), so don't do a fresh - * GetCurrentTimestamp() call (which'd be expensive anyway). In a - * parallel worker, this should already have been provided by a call to + * set transaction_timestamp() (a/k/a now()). Normally, we want this to + * be the same as the first command's statement_timestamp(), so don't do a + * fresh GetCurrentTimestamp() call (which'd be expensive anyway). But + * for transactions started inside procedures (i.e., nonatomic SPI + * contexts), we do need to advance the timestamp. Also, in a parallel + * worker, the timestamp should already have been provided by a call to * SetParallelStartTimestamps(). - * - * Also, mark xactStopTimestamp as unset. */ if (!IsParallelWorker()) - xactStartTimestamp = stmtStartTimestamp; + { + if (!SPI_inside_nonatomic_context()) + xactStartTimestamp = stmtStartTimestamp; + else + xactStartTimestamp = GetCurrentTimestamp(); + } else Assert(xactStartTimestamp != 0); - xactStopTimestamp = 0; pgstat_report_xact_timestamp(xactStartTimestamp); + /* Mark xactStopTimestamp as unset. */ + xactStopTimestamp = 0; /* * initialize current transaction state fields diff --git a/src/backend/executor/spi.c b/src/backend/executor/spi.c index 11ca800e4c..fb36e762f2 100644 --- a/src/backend/executor/spi.c +++ b/src/backend/executor/spi.c @@ -423,6 +423,19 @@ AtEOSubXact_SPI(bool isCommit, SubTransactionId mySubid) } } +/* + * Are we executing inside a procedure (that is, a nonatomic SPI context)? + */ +bool +SPI_inside_nonatomic_context(void) +{ + if (_SPI_current == NULL) + return false; /* not in any SPI context at all */ + if (_SPI_current->atomic) + return false; /* it's atomic (ie function not procedure) */ + return true; +} + /* Parse, plan, and execute a query string */ int diff --git a/src/include/executor/spi.h b/src/include/executor/spi.h index 143a89a16c..b16440cf00 100644 --- a/src/include/executor/spi.h +++ b/src/include/executor/spi.h @@ -166,5 +166,6 @@ extern void SPI_rollback(void); extern void SPICleanup(void); extern void AtEOXact_SPI(bool isCommit); extern void AtEOSubXact_SPI(bool isCommit, SubTransactionId mySubid); +extern bool SPI_inside_nonatomic_context(void); #endif /* SPI_H */ diff --git a/src/pl/plpgsql/src/expected/plpgsql_transaction.out b/src/pl/plpgsql/src/expected/plpgsql_transaction.out index 77a83adab5..6eedb215a4 100644 --- a/src/pl/plpgsql/src/expected/plpgsql_transaction.out +++ b/src/pl/plpgsql/src/expected/plpgsql_transaction.out @@ -493,6 +493,36 @@ CALL transaction_test10b(10); 9 (1 row) +-- transaction timestamp vs. statement timestamp +CREATE PROCEDURE transaction_test11() +LANGUAGE plpgsql +AS $$ +DECLARE + s1 timestamp with time zone; + s2 timestamp with time zone; + s3 timestamp with time zone; + t1 timestamp with time zone; + t2 timestamp with time zone; + t3 timestamp with time zone; +BEGIN + s1 := statement_timestamp(); + t1 := transaction_timestamp(); + ASSERT s1 = t1; + PERFORM pg_sleep(0.001); + COMMIT; + s2 := statement_timestamp(); + t2 := transaction_timestamp(); + ASSERT s2 = s1; + ASSERT t2 > t1; + PERFORM pg_sleep(0.001); + ROLLBACK; + s3 := statement_timestamp(); + t3 := transaction_timestamp(); + ASSERT s3 = s1; + ASSERT t3 > t2; +END; +$$; +CALL transaction_test11(); DROP TABLE test1; DROP TABLE test2; DROP TABLE test3; diff --git a/src/pl/plpgsql/src/sql/plpgsql_transaction.sql b/src/pl/plpgsql/src/sql/plpgsql_transaction.sql index 0ed9ab873a..ac1361a8ce 100644 --- a/src/pl/plpgsql/src/sql/plpgsql_transaction.sql +++ b/src/pl/plpgsql/src/sql/plpgsql_transaction.sql @@ -412,6 +412,39 @@ $$; CALL transaction_test10b(10); +-- transaction timestamp vs. statement timestamp +CREATE PROCEDURE transaction_test11() +LANGUAGE plpgsql +AS $$ +DECLARE + s1 timestamp with time zone; + s2 timestamp with time zone; + s3 timestamp with time zone; + t1 timestamp with time zone; + t2 timestamp with time zone; + t3 timestamp with time zone; +BEGIN + s1 := statement_timestamp(); + t1 := transaction_timestamp(); + ASSERT s1 = t1; + PERFORM pg_sleep(0.001); + COMMIT; + s2 := statement_timestamp(); + t2 := transaction_timestamp(); + ASSERT s2 = s1; + ASSERT t2 > t1; + PERFORM pg_sleep(0.001); + ROLLBACK; + s3 := statement_timestamp(); + t3 := transaction_timestamp(); + ASSERT s3 = s1; + ASSERT t3 > t2; +END; +$$; + +CALL transaction_test11(); + + DROP TABLE test1; DROP TABLE test2; DROP TABLE test3; -- 2.40.0