v2-0001-Advance-transaction-timestamp-in-intra-procedure-.patch

From a7b7c4094a54f9b217332809b1abfb521a4b994d Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter_e@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