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Up to now, SerializableSnapshot and QuerySnapshot are malloc'ed and

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free'd for every transaction or statement, respectively.  This patch
puts these data structures into static memory, thus saving a few CPU
cycles and two malloc calls per transaction or (in isolation level
READ COMMITTED) per query.

Manfred Koizar
This commit is contained in:
Bruce Momjian
2003-06-12 01:42:21 +00:00
parent 752a4dac50
commit acd1536d9f
3 changed files with 30 additions and 33 deletions
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33
src/backend/utils/time/tqual.c
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@@ -16,7 +16,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/time/tqual.c,v 1.62 2003/02/23 23:20:52 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/time/tqual.c,v 1.63 2003/06/12 01:42:20 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@@ -30,6 +30,8 @@
static SnapshotData SnapshotDirtyData;
Snapshot SnapshotDirty = &SnapshotDirtyData;
static SnapshotData QuerySnapshotData;
static SnapshotData SerializableSnapshotData;
Snapshot QuerySnapshot = NULL;
Snapshot SerializableSnapshot = NULL;
@@ -941,23 +943,16 @@ SetQuerySnapshot(void)
/* 1st call in xaction? */
if (SerializableSnapshot == NULL)
{
SerializableSnapshot = GetSnapshotData(true);
SerializableSnapshot = GetSnapshotData(&SerializableSnapshotData, true);
QuerySnapshot = SerializableSnapshot;
Assert(QuerySnapshot != NULL);
return;
}
if (QuerySnapshot != SerializableSnapshot)
{
free(QuerySnapshot->xip);
free(QuerySnapshot);
QuerySnapshot = NULL;
}
if (XactIsoLevel == XACT_SERIALIZABLE)
QuerySnapshot = SerializableSnapshot;
else
QuerySnapshot = GetSnapshotData(false);
QuerySnapshot = GetSnapshotData(&QuerySnapshotData, false);
Assert(QuerySnapshot != NULL);
}
@@ -1003,19 +998,11 @@ CopyQuerySnapshot(void)
void
FreeXactSnapshot(void)
{
if (QuerySnapshot != NULL && QuerySnapshot != SerializableSnapshot)
{
free(QuerySnapshot->xip);
free(QuerySnapshot);
}
/*
* We do not free(QuerySnapshot->xip);
* or free(SerializableSnapshot->xip);
* they will be reused soon
*/
QuerySnapshot = NULL;
if (SerializableSnapshot != NULL)
{
free(SerializableSnapshot->xip);
free(SerializableSnapshot);
}
SerializableSnapshot = NULL;
}