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Add temp_buffers GUC variable to allow users to determine the size
of the local buffer arena for temporary table access.
1 parent d65522a commit 91728fa

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8 files changed

+89
-28
lines changed

8 files changed

+89
-28
lines changed

‎doc/src/sgml/runtime.sgml‎

Lines changed: 28 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
<!--
2-
$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.309 2005/03/14 06:49:48 neilc Exp $
2+
$PostgreSQL: pgsql/doc/src/sgml/runtime.sgml,v 1.310 2005/03/19 23:27:04 tgl Exp $
33
-->
44

55
<chapter Id="runtime">
@@ -1038,6 +1038,33 @@ SET ENABLE_SEQSCAN TO OFF;
10381038
</listitem>
10391039
</varlistentry>
10401040

1041+
<varlistentry id="guc-temp-buffers" xreflabel="temp_buffers">
1042+
<term><varname>temp_buffers</varname> (<type>integer</type>)</term>
1043+
<indexterm>
1044+
<primary><varname>temp_buffers</> configuration parameter</primary>
1045+
</indexterm>
1046+
<listitem>
1047+
<para>
1048+
Sets the maximum number of temporary buffers used by each database
1049+
session. These are session-local buffers used only for access
1050+
to temporary tables. The default is 1000. The setting can
1051+
be changed within individual sessions, but only up until the
1052+
first use of temporary tables within a session; subsequent
1053+
attempts to change the value will have no effect on that session.
1054+
</para>
1055+
1056+
<para>
1057+
A session will allocate temporary buffers as needed up to the limit
1058+
given by <varname>temp_buffers</>. The cost of setting a large
1059+
value in sessions that do not actually need a lot of temporary
1060+
buffers is only a buffer descriptor, or about 64 bytes, per
1061+
increment in <varname>temp_buffers</>. However if a buffer is
1062+
actually used an additional 8192 bytes will be consumed for it
1063+
(or in general <symbol>BLCKSZ</symbol> bytes).
1064+
</para>
1065+
</listitem>
1066+
</varlistentry>
1067+
10411068
<varlistentry id="guc-work-mem" xreflabel="work_mem">
10421069
<term><varname>work_mem</varname> (<type>integer</type>)</term>
10431070
<indexterm>

‎src/backend/storage/buffer/localbuf.c‎

Lines changed: 27 additions & 19 deletions
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,7 @@
99
*
1010
*
1111
* IDENTIFICATION
12-
* $PostgreSQL: pgsql/src/backend/storage/buffer/localbuf.c,v 1.65 2005/03/19 17:39:43 tgl Exp $
12+
* $PostgreSQL: pgsql/src/backend/storage/buffer/localbuf.c,v 1.66 2005/03/19 23:27:05 tgl Exp $
1313
*
1414
*-------------------------------------------------------------------------
1515
*/
@@ -18,6 +18,7 @@
1818
#include "storage/buf_internals.h"
1919
#include "storage/bufmgr.h"
2020
#include "storage/smgr.h"
21+
#include "utils/guc.h"
2122
#include "utils/memutils.h"
2223
#include "utils/resowner.h"
2324

@@ -46,6 +47,9 @@ static int nextFreeLocalBuf = 0;
4647
static HTAB *LocalBufHash = NULL;
4748

4849

50+
static void InitLocalBuffers(void);
51+
52+
4953
/*
5054
* LocalBufferAlloc -
5155
* Find or create a local buffer for the given page of the given relation.
@@ -66,6 +70,10 @@ LocalBufferAlloc(Relation reln, BlockNumber blockNum, bool *foundPtr)
6670

6771
INIT_BUFFERTAG(newTag, reln, blockNum);
6872

73+
/* Initialize local buffers if first request in this session */
74+
if (LocalBufHash == NULL)
75+
InitLocalBuffers();
76+
6977
/* See if the desired buffer already exists */
7078
hresult = (LocalBufferLookupEnt *)
7179
hash_search(LocalBufHash, (void *) &newTag, HASH_FIND, NULL);
@@ -238,32 +246,18 @@ WriteLocalBuffer(Buffer buffer, bool release)
238246
}
239247

240248
/*
241-
* InitLocalBuffer -
249+
* InitLocalBuffers -
242250
* init the local buffer cache. Since most queries (esp. multi-user ones)
243251
* don't involve local buffers, we delay allocating actual memory for the
244252
* buffers until we need them; just make the buffer headers here.
245253
*/
246-
void
247-
InitLocalBuffer(void)
254+
static void
255+
InitLocalBuffers(void)
248256
{
249-
int nbufs = 64; /* should be from a GUC var */
257+
int nbufs = num_temp_buffers;
250258
HASHCTL info;
251259
int i;
252260

253-
/* Create the lookup hash table */
254-
MemSet(&info, 0, sizeof(info));
255-
info.keysize = sizeof(BufferTag);
256-
info.entrysize = sizeof(LocalBufferLookupEnt);
257-
info.hash = tag_hash;
258-
259-
LocalBufHash = hash_create("Local Buffer Lookup Table",
260-
nbufs,
261-
&info,
262-
HASH_ELEM | HASH_FUNCTION);
263-
264-
if (!LocalBufHash)
265-
elog(ERROR, "could not initialize local buffer hash table");
266-
267261
/* Allocate and zero buffer headers and auxiliary arrays */
268262
LocalBufferDescriptors = (BufferDesc *)
269263
MemoryContextAllocZero(TopMemoryContext,
@@ -291,6 +285,20 @@ InitLocalBuffer(void)
291285
buf->buf_id = -i - 2;
292286
}
293287

288+
/* Create the lookup hash table */
289+
MemSet(&info, 0, sizeof(info));
290+
info.keysize = sizeof(BufferTag);
291+
info.entrysize = sizeof(LocalBufferLookupEnt);
292+
info.hash = tag_hash;
293+
294+
LocalBufHash = hash_create("Local Buffer Lookup Table",
295+
nbufs,
296+
&info,
297+
HASH_ELEM | HASH_FUNCTION);
298+
299+
if (!LocalBufHash)
300+
elog(ERROR, "could not initialize local buffer hash table");
301+
294302
/* Initialization done, mark buffers allocated */
295303
NLocBuffer = nbufs;
296304
}

‎src/backend/utils/init/postinit.c‎

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/utils/init/postinit.c,v 1.143 2005/03/18 16:16:09 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/utils/init/postinit.c,v 1.144 2005/03/19 23:27:06 tgl Exp $
1212
*
1313
*
1414
*-------------------------------------------------------------------------
@@ -257,7 +257,6 @@ BaseInit(void)
257257
/* Do local initialization of storage and buffer managers */
258258
smgrinit();
259259
InitBufferPoolAccess();
260-
InitLocalBuffer();
261260
}
262261

263262

‎src/backend/utils/misc/guc.c‎

Lines changed: 26 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,7 @@
1010
* Written by Peter Eisentraut <peter_e@gmx.net>.
1111
*
1212
* IDENTIFICATION
13-
* $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.255 2005/03/13 09:36:31 neilc Exp $
13+
* $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.256 2005/03/19 23:27:07 tgl Exp $
1414
*
1515
*--------------------------------------------------------------------
1616
*/
@@ -104,6 +104,7 @@ static const char *assign_log_error_verbosity(const char *newval, bool doit,
104104
GucSource source);
105105
static const char *assign_log_statement(const char *newval, bool doit,
106106
GucSource source);
107+
static const char *show_num_temp_buffers(void);
107108
static bool assign_phony_autocommit(bool newval, bool doit, GucSource source);
108109
static const char *assign_custom_variable_classes(const char *newval, bool doit,
109110
GucSource source);
@@ -144,9 +145,10 @@ bool default_with_oids = false;
144145
int log_min_error_statement = PANIC;
145146
int log_min_messages = NOTICE;
146147
int client_min_messages = NOTICE;
147-
148148
int log_min_duration_statement = -1;
149149

150+
int num_temp_buffers = 1000;
151+
150152
char *ConfigFileName;
151153
char *HbaFileName;
152154
char *IdentFileName;
@@ -966,6 +968,15 @@ static struct config_int ConfigureNamesInt[] =
966968
1000, 16, INT_MAX / BLCKSZ, NULL, NULL
967969
},
968970

971+
{
972+
{"temp_buffers", PGC_USERSET, RESOURCES_MEM,
973+
gettext_noop("Sets the maximum number of temporary buffers used by each session."),
974+
NULL
975+
},
976+
&num_temp_buffers,
977+
1000, 100, INT_MAX / BLCKSZ, NULL, show_num_temp_buffers
978+
},
979+
969980
{
970981
{"port", PGC_POSTMASTER, CONN_AUTH_SETTINGS,
971982
gettext_noop("Sets the TCP port the server listens on."),
@@ -5496,6 +5507,19 @@ assign_log_statement(const char *newval, bool doit, GucSource source)
54965507
return newval; /* OK */
54975508
}
54985509

5510+
static const char *
5511+
show_num_temp_buffers(void)
5512+
{
5513+
/*
5514+
* We show the GUC var until local buffers have been initialized,
5515+
* and NLocBuffer afterwards.
5516+
*/
5517+
static char nbuf[32];
5518+
5519+
sprintf(nbuf, "%d", NLocBuffer ? NLocBuffer : num_temp_buffers);
5520+
return nbuf;
5521+
}
5522+
54995523
static bool
55005524
assign_phony_autocommit(bool newval, bool doit, GucSource source)
55015525
{

‎src/backend/utils/misc/postgresql.conf.sample‎

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -74,6 +74,7 @@
7474
# - Memory -
7575

7676
#shared_buffers = 1000 # min 16, at least max_connections*2, 8KB each
77+
#temp_buffers = 1000 # min 100, 8KB each
7778
#work_mem = 1024 # min 64, size in KB
7879
#maintenance_work_mem = 16384 # min 1024, size in KB
7980
#max_stack_depth = 2048 # min 100, size in KB

‎src/bin/psql/tab-complete.c‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -3,7 +3,7 @@
33
*
44
* Copyright (c) 2000-2005, PostgreSQL Global Development Group
55
*
6-
* $PostgreSQL: pgsql/src/bin/psql/tab-complete.c,v 1.121 2005/01/23 15:58:50 momjian Exp $
6+
* $PostgreSQL: pgsql/src/bin/psql/tab-complete.c,v 1.122 2005/03/19 23:27:08 tgl Exp $
77
*/
88

99
/*----------------------------------------------------------------------
@@ -594,6 +594,7 @@ psql_completion(char *text, int start, int end)
594594
"superuser_reserved_connections",
595595
"syslog_facility",
596596
"syslog_ident",
597+
"temp_buffers",
597598
"TimeZone",
598599
"trace_notify",
599600
"transform_null_equals",

‎src/include/storage/bufmgr.h‎

Lines changed: 1 addition & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10-
* $PostgreSQL: pgsql/src/include/storage/bufmgr.h,v 1.91 2005/03/18 16:16:09 tgl Exp $
10+
* $PostgreSQL: pgsql/src/include/storage/bufmgr.h,v 1.92 2005/03/19 23:27:10 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -157,7 +157,6 @@ extern void BufmgrCommit(void);
157157
extern void BufferSync(void);
158158
extern void BgBufferSync(void);
159159

160-
extern void InitLocalBuffer(void);
161160
extern void AtProcExit_LocalBuffers(void);
162161

163162
/* in freelist.c */

‎src/include/utils/guc.h‎

Lines changed: 3 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Copyright (c) 2000-2005, PostgreSQL Global Development Group
88
* Written by Peter Eisentraut <peter_e@gmx.net>.
99
*
10-
* $PostgreSQL: pgsql/src/include/utils/guc.h,v 1.58 2005/01/01 05:43:09 momjian Exp $
10+
* $PostgreSQL: pgsql/src/include/utils/guc.h,v 1.59 2005/03/19 23:27:11 tgl Exp $
1111
*--------------------------------------------------------------------
1212
*/
1313
#ifndef GUC_H
@@ -126,6 +126,8 @@ extern int log_min_messages;
126126
extern int client_min_messages;
127127
extern int log_min_duration_statement;
128128

129+
extern int num_temp_buffers;
130+
129131
extern char *ConfigFileName;
130132
extern char *HbaFileName;
131133
extern char *IdentFileName;

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