From 71901ab6daaad65c0168c05e016e4208efe5b71a Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 9 Sep 2013 16:25:29 -0400
Subject: [PATCH] Introduce InvalidCommandId.
This allows a 32-bit field to represent an *optional* command ID
without a separate flag bit.
Andres Freund
---
src/backend/access/transam/xact.c | 4 ++--
src/include/c.h | 1 +
2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 31e868d4bc7..0591f3fd562 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -766,12 +766,12 @@ CommandCounterIncrement(void)
if (currentCommandIdUsed)
{
currentCommandId += 1;
- if (currentCommandId == FirstCommandId) /* check for overflow */
+ if (currentCommandId == InvalidCommandId)
{
currentCommandId -= 1;
ereport(ERROR,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
- errmsg("cannot have more than 2^32-1 commands in a transaction")));
+ errmsg("cannot have more than 2^32-2 commands in a transaction")));
}
currentCommandIdUsed = false;
diff --git a/src/include/c.h b/src/include/c.h
index 596118342df..14bfdcd4dab 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -368,6 +368,7 @@ typedef uint32 MultiXactOffset;
typedef uint32 CommandId;
#define FirstCommandId ((CommandId) 0)
+#define InvalidCommandId (~(CommandId)0)
/*
* Array indexing support
--
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