On 02/10/2018 16:58, Andres Freund wrote:
> It's a bit weird to make this decision based on these two timestamps
> differing. For one, it only indirectly seems to be guaranteed that
> xactStartTimestamp is even set to anything here (to 0 by virtue of being
> a global var).
Maybe but it seems to be the simplest way without doing major surgery to
all this code.
Attached is an updated patch with a test case.
--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
From a7b7c4094a54f9b217332809b1abfb521a4b994d Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <pete...@gmx.net>
Date: Fri, 5 Oct 2018 12:24:34 +0200
Subject: [PATCH v2] Advance transaction timestamp in intra-procedure
transactions
---
src/backend/access/transam/xact.c | 19 +++++++-----
.../src/expected/plpgsql_transaction.out | 28 +++++++++++++++++
.../plpgsql/src/sql/plpgsql_transaction.sql | 31 +++++++++++++++++++
3 files changed, 71 insertions(+), 7 deletions(-)
diff --git a/src/backend/access/transam/xact.c
b/src/backend/access/transam/xact.c
index 9aa63c8792..245735420c 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -1884,14 +1884,19 @@ 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). Also, mark
- * xactStopTimestamp as unset.
- */
- xactStartTimestamp = stmtStartTimestamp;
- xactStopTimestamp = 0;
+ * 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 statements (e.g., procedure calls),
we
+ * want to advance the timestamp.
+ */
+ if (xactStartTimestamp < stmtStartTimestamp)
+ xactStartTimestamp = stmtStartTimestamp;
+ else
+ xactStartTimestamp = GetCurrentTimestamp();
pgstat_report_xact_timestamp(xactStartTimestamp);
+ /* Mark xactStopTimestamp as unset. */
+ xactStopTimestamp = 0;
/*
* initialize current transaction state fields
diff --git a/src/pl/plpgsql/src/expected/plpgsql_transaction.out
b/src/pl/plpgsql/src/expected/plpgsql_transaction.out
index 77a83adab5..71e56300bc 100644
--- a/src/pl/plpgsql/src/expected/plpgsql_transaction.out
+++ b/src/pl/plpgsql/src/expected/plpgsql_transaction.out
@@ -493,6 +493,34 @@ CALL transaction_test10b(10);
9
(1 row)
+-- transaction timestamp vs. statement timestamp
+CREATE PROCEDURE transaction_test11()
+LANGUAGE plpgsql
+AS $$
+DECLARE
+ s1 timestamp with time zone;
+ s2 timestamp with time zone;
+ s3 timestamp with time zone;
+ t1 timestamp with time zone;
+ t2 timestamp with time zone;
+ t3 timestamp with time zone;
+BEGIN
+ s1 := statement_timestamp();
+ t1 := transaction_timestamp();
+ ASSERT s1 = t1;
+ COMMIT;
+ s2 := statement_timestamp();
+ t2 := transaction_timestamp();
+ ASSERT s2 = s1;
+ ASSERT t2 > t1;
+ ROLLBACK;
+ s3 := statement_timestamp();
+ t3 := transaction_timestamp();
+ ASSERT s3 = s1;
+ ASSERT t3 > t2;
+END;
+$$;
+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..e2089f56ad 100644
--- a/src/pl/plpgsql/src/sql/plpgsql_transaction.sql
+++ b/src/pl/plpgsql/src/sql/plpgsql_transaction.sql
@@ -412,6 +412,37 @@ CREATE PROCEDURE transaction_test10b(INOUT x int)
CALL transaction_test10b(10);
+-- transaction timestamp vs. statement timestamp
+CREATE PROCEDURE transaction_test11()
+LANGUAGE plpgsql
+AS $$
+DECLARE
+ s1 timestamp with time zone;
+ s2 timestamp with time zone;
+ s3 timestamp with time zone;
+ t1 timestamp with time zone;
+ t2 timestamp with time zone;
+ t3 timestamp with time zone;
+BEGIN
+ s1 := statement_timestamp();
+ t1 := transaction_timestamp();
+ ASSERT s1 = t1;
+ COMMIT;
+ s2 := statement_timestamp();
+ t2 := transaction_timestamp();
+ ASSERT s2 = s1;
+ ASSERT t2 > t1;
+ ROLLBACK;
+ s3 := statement_timestamp();
+ t3 := transaction_timestamp();
+ ASSERT s3 = s1;
+ ASSERT t3 > t2;
+END;
+$$;
+
+CALL transaction_test11();
+
+
DROP TABLE test1;
DROP TABLE test2;
DROP TABLE test3;
base-commit: ff347f8aff04865680c19ffc818460bb2afaad5b
--
2.19.0
