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Rewrite the FSM. Instead of relying on a fixed-size shared memory segment, the
free space information is stored in a dedicated FSM relation fork, with each relation (except for hash indexes; they don't use FSM). This eliminates the max_fsm_relations and max_fsm_pages GUC options; remove any trace of them from the backend, initdb, and documentation. Rewrite contrib/pg_freespacemap to match the new FSM implementation. Also introduce a new variant of the get_raw_page(regclass, int4, int4) function in contrib/pageinspect that let's you to return pages from any relation fork, and a new fsm_page_contents() function to inspect the new FSM pages.
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‎contrib/pageinspect/Makefile‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -2,12 +2,12 @@
22
#
33
# pageinspect Makefile
44
#
5-
# $PostgreSQL: pgsql/contrib/pageinspect/Makefile,v 1.3 2007/11/10 23:59:51 momjian Exp $
5+
# $PostgreSQL: pgsql/contrib/pageinspect/Makefile,v 1.4 2008/09/30 10:52:09 heikki Exp $
66
#
77
#-------------------------------------------------------------------------
88

99
MODULE_big = pageinspect
10-
OBJS = rawpage.o heapfuncs.o btreefuncs.o
10+
OBJS = rawpage.o heapfuncs.o btreefuncs.o fsmfuncs.o
1111
DATA_built = pageinspect.sql
1212
DATA = uninstall_pageinspect.sql
1313

‎contrib/pageinspect/fsmfuncs.c‎

Lines changed: 61 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,61 @@
1+
/*-------------------------------------------------------------------------
2+
*
3+
* fsmfuncs.c
4+
* Functions to investigate FSM pages
5+
*
6+
* These functions are restricted to superusers for the fear of introducing
7+
* security holes if the input checking isn't as water-tight as it should.
8+
* You'd need to be superuser to obtain a raw page image anyway, so
9+
* there's hardly any use case for using these without superuser-rights
10+
* anyway.
11+
*
12+
* Copyright (c) 2007-2008, PostgreSQL Global Development Group
13+
*
14+
* IDENTIFICATION
15+
* $PostgreSQL: pgsql/contrib/pageinspect/fsmfuncs.c,v 1.1 2008/09/30 10:52:09 heikki Exp $
16+
*
17+
*-------------------------------------------------------------------------
18+
*/
19+
20+
#include "postgres.h"
21+
#include "lib/stringinfo.h"
22+
#include "storage/fsm_internals.h"
23+
#include "utils/builtins.h"
24+
#include "miscadmin.h"
25+
#include "funcapi.h"
26+
27+
Datum fsm_page_contents(PG_FUNCTION_ARGS);
28+
29+
/*
30+
* Dumps the contents of a FSM page.
31+
*/
32+
PG_FUNCTION_INFO_V1(fsm_page_contents);
33+
34+
Datum
35+
fsm_page_contents(PG_FUNCTION_ARGS)
36+
{
37+
bytea *raw_page = PG_GETARG_BYTEA_P(0);
38+
int raw_page_size;
39+
StringInfoData sinfo;
40+
FSMPage fsmpage;
41+
int i;
42+
43+
if (!superuser())
44+
ereport(ERROR,
45+
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
46+
(errmsg("must be superuser to use raw page functions"))));
47+
48+
raw_page_size = VARSIZE(raw_page) - VARHDRSZ;
49+
fsmpage = (FSMPage) PageGetContents(VARDATA(raw_page));
50+
51+
initStringInfo(&sinfo);
52+
53+
for(i=0; i < NodesPerPage; i++)
54+
{
55+
if (fsmpage->fp_nodes[i] != 0)
56+
appendStringInfo(&sinfo, "%d: %d\n", i, fsmpage->fp_nodes[i]);
57+
}
58+
appendStringInfo(&sinfo, "fp_next_slot: %d\n", fsmpage->fp_next_slot);
59+
60+
PG_RETURN_TEXT_P(cstring_to_text(sinfo.data));
61+
}

‎contrib/pageinspect/pageinspect.sql.in‎

Lines changed: 15 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,16 +1,21 @@
1-
/* $PostgreSQL: pgsql/contrib/pageinspect/pageinspect.sql.in,v 1.4 2007/11/13 04:24:28 momjian Exp $ */
1+
/* $PostgreSQL: pgsql/contrib/pageinspect/pageinspect.sql.in,v 1.5 2008/09/30 10:52:09 heikki Exp $ */
22

33
-- Adjust this setting to control where the objects get created.
44
SET search_path = public;
55

66
--
77
-- get_raw_page()
88
--
9-
CREATE OR REPLACE FUNCTION get_raw_page(text, int4)
9+
CREATE OR REPLACE FUNCTION get_raw_page(text, int4, int4)
1010
RETURNS bytea
1111
AS 'MODULE_PATHNAME', 'get_raw_page'
1212
LANGUAGE C STRICT;
1313

14+
CREATE OR REPLACE FUNCTION get_raw_page(text, int4)
15+
RETURNS bytea
16+
AS $$ SELECT get_raw_page($1, 0, $2); $$
17+
LANGUAGE SQL STRICT;
18+
1419
--
1520
-- page_header()
1621
--
@@ -92,3 +97,11 @@ CREATE OR REPLACE FUNCTION bt_page_items(IN relname text, IN blkno int4,
9297
RETURNS SETOF record
9398
AS 'MODULE_PATHNAME', 'bt_page_items'
9499
LANGUAGE C STRICT;
100+
101+
--
102+
-- fsm_page_contents()
103+
--
104+
CREATE OR REPLACE FUNCTION fsm_page_contents(IN page bytea)
105+
RETURNS text
106+
AS 'MODULE_PATHNAME', 'fsm_page_contents'
107+
LANGUAGE C STRICT;

‎contrib/pageinspect/rawpage.c‎

Lines changed: 9 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
* Copyright (c) 2007-2008, PostgreSQL Global Development Group
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/contrib/pageinspect/rawpage.c,v 1.6 2008/05/12 00:00:43 alvherre Exp $
11+
* $PostgreSQL: pgsql/contrib/pageinspect/rawpage.c,v 1.7 2008/09/30 10:52:09 heikki Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -41,7 +41,8 @@ Datum
4141
get_raw_page(PG_FUNCTION_ARGS)
4242
{
4343
text *relname = PG_GETARG_TEXT_P(0);
44-
uint32 blkno = PG_GETARG_UINT32(1);
44+
uint32 forknum = PG_GETARG_UINT32(1);
45+
uint32 blkno = PG_GETARG_UINT32(2);
4546

4647
Relation rel;
4748
RangeVar *relrv;
@@ -54,6 +55,11 @@ get_raw_page(PG_FUNCTION_ARGS)
5455
(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
5556
(errmsg("must be superuser to use raw functions"))));
5657

58+
if (forknum > MAX_FORKNUM)
59+
ereport(ERROR,
60+
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
61+
errmsg("invalid fork number")));
62+
5763
relrv = makeRangeVarFromNameList(textToQualifiedNameList(relname));
5864
rel = relation_openrv(relrv, AccessShareLock);
5965

@@ -80,7 +86,7 @@ get_raw_page(PG_FUNCTION_ARGS)
8086

8187
/* Take a verbatim copy of the page */
8288

83-
buf = ReadBuffer(rel, blkno);
89+
buf = ReadBufferWithFork(rel, forknum, blkno);
8490
LockBuffer(buf, BUFFER_LOCK_SHARE);
8591

8692
memcpy(raw_page_data, BufferGetPage(buf), BLCKSZ);

‎contrib/pg_freespacemap/pg_freespacemap.sql.in‎

Lines changed: 15 additions & 33 deletions
Original file line numberDiff line numberDiff line change
@@ -1,44 +1,26 @@
1-
/* $PostgreSQL: pgsql/contrib/pg_freespacemap/pg_freespacemap.sql.in,v 1.8 2007/11/13 04:24:28 momjian Exp $ */
1+
/* $PostgreSQL: pgsql/contrib/pg_freespacemap/pg_freespacemap.sql.in,v 1.9 2008/09/30 10:52:09 heikki Exp $ */
22

33
-- Adjust this setting to control where the objects get created.
44
SET search_path = public;
55

66

7-
-- Register the functions.
8-
CREATE OR REPLACE FUNCTION pg_freespacemap_pages()
9-
RETURNS SETOF RECORD
10-
AS 'MODULE_PATHNAME', 'pg_freespacemap_pages'
7+
-- Register the C function.
8+
CREATE OR REPLACE FUNCTION pg_freespace(regclass, int4)
9+
RETURNS int2
10+
AS 'MODULE_PATHNAME', 'pg_freespace'
1111
LANGUAGE C;
1212

13-
CREATE OR REPLACE FUNCTION pg_freespacemap_relations()
13+
-- pg_freespace shows the recorded space avail at each block in a relation
14+
CREATE OR REPLACE FUNCTION
15+
pg_freespace(rel regclass, blkno OUT int4, avail OUT int2)
1416
RETURNS SETOF RECORD
15-
AS 'MODULE_PATHNAME', 'pg_freespacemap_relations'
16-
LANGUAGE C;
17+
AS $$
18+
SELECT blkno::int4, pg_freespace($1, blkno::int4) AS avail
19+
FROM generate_series(0, pg_relation_size($1) / current_setting('block_size')::bigint - 1) AS blkno;
20+
$$
21+
LANGUAGE SQL;
1722

1823

19-
-- Create views for convenient access.
20-
CREATE VIEW pg_freespacemap_pages AS
21-
SELECT P.* FROM pg_freespacemap_pages() AS P
22-
(reltablespace oid,
23-
reldatabase oid,
24-
relfilenode oid,
25-
relblocknumber bigint,
26-
bytes integer);
27-
28-
CREATE VIEW pg_freespacemap_relations AS
29-
SELECT P.* FROM pg_freespacemap_relations() AS P
30-
(reltablespace oid,
31-
reldatabase oid,
32-
relfilenode oid,
33-
avgrequest integer,
34-
interestingpages integer,
35-
storedpages integer,
36-
nextpage integer);
37-
38-
3924
-- Don't want these to be available to public.
40-
REVOKE ALL ON FUNCTION pg_freespacemap_pages() FROM PUBLIC;
41-
REVOKE ALL ON pg_freespacemap_pages FROM PUBLIC;
42-
43-
REVOKE ALL ON FUNCTION pg_freespacemap_relations() FROM PUBLIC;
44-
REVOKE ALL ON pg_freespacemap_relations FROM PUBLIC;
25+
REVOKE ALL ON FUNCTION pg_freespace(regclass, int4) FROM PUBLIC;
26+
REVOKE ALL ON FUNCTION pg_freespace(regclass) FROM PUBLIC;

‎doc/src/sgml/acronyms.sgml‎

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
<!-- $PostgreSQL: pgsql/doc/src/sgml/acronyms.sgml,v 1.5 2008/03/18 16:05:07 mha Exp $ -->
1+
<!-- $PostgreSQL: pgsql/doc/src/sgml/acronyms.sgml,v 1.6 2008/09/30 10:52:09 heikki Exp $ -->
22

33
<appendix id="acronyms">
44
<title>Acronyms</title>
@@ -216,7 +216,7 @@
216216
<term><acronym>FSM</acronym></term>
217217
<listitem>
218218
<para>
219-
<link linkend="runtime-config-resource-fsm">Free Space Map</link>
219+
<link linkend="storage-fsm">Free Space Map</link>
220220
</para>
221221
</listitem>
222222
</varlistentry>

‎doc/src/sgml/config.sgml‎

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Original file line numberDiff line numberDiff line change
@@ -1,4 +1,4 @@
1-
<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.190 2008/08/25 19:03:37 tgl Exp $ -->
1+
<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.191 2008/09/30 10:52:09 heikki Exp $ -->
22

33
<chapter Id="runtime-config">
44
<title>Server Configuration</title>
@@ -896,80 +896,6 @@ SET ENABLE_SEQSCAN TO OFF;
896896
</varlistentry>
897897

898898
</variablelist>
899-
</sect2>
900-
<sect2 id="runtime-config-resource-fsm">
901-
<title>Free Space Map</title>
902-
903-
<indexterm>
904-
<primary>free space map</primary>
905-
</indexterm>
906-
907-
<para>
908-
These parameters control the size of the shared <firstterm>free space
909-
map</> (<acronym>FSM</>), which tracks the locations of unused space in the database.
910-
An undersized free space map can cause the database to consume
911-
increasing amounts of disk space over time, because free space that
912-
is not in the map cannot be re-used; instead <productname>PostgreSQL</>
913-
will request more disk space from the operating system when it needs
914-
to store new data.
915-
The last few lines displayed by a database-wide <command>VACUUM VERBOSE</>
916-
command can help in determining if the current settings are adequate.
917-
A <literal>NOTICE</> message is also printed during such an operation
918-
if the current settings are too low.
919-
</para>
920-
921-
<para>
922-
Increasing these parameters might cause <productname>PostgreSQL</>
923-
to request more <systemitem class="osname">System V</> shared
924-
memory than your operating system's default configuration
925-
allows. See <xref linkend="sysvipc"> for information on how to
926-
adjust those parameters, if necessary.
927-
</para>
928-
929-
<variablelist>
930-
<varlistentry id="guc-max-fsm-pages" xreflabel="max_fsm_pages">
931-
<term><varname>max_fsm_pages</varname> (<type>integer</type>)</term>
932-
<indexterm>
933-
<primary><varname>max_fsm_pages</> configuration parameter</primary>
934-
</indexterm>
935-
<listitem>
936-
<para>
937-
Sets the maximum number of disk pages for which free space will
938-
be tracked in the shared free-space map. Six bytes of shared memory
939-
are consumed for each page slot. This setting must be at least
940-
16 * <varname>max_fsm_relations</varname>. The default is chosen
941-
by <application>initdb</> depending on the amount of available memory,
942-
and can range from 20k to 200k pages.
943-
This parameter can only be set at server start.
944-
</para>
945-
</listitem>
946-
</varlistentry>
947-
948-
<varlistentry id="guc-max-fsm-relations" xreflabel="max_fsm_relations">
949-
<term><varname>max_fsm_relations</varname> (<type>integer</type>)</term>
950-
<indexterm>
951-
<primary><varname>max_fsm_relations</> configuration parameter</primary>
952-
</indexterm>
953-
<listitem>
954-
<para>
955-
Sets the maximum number of relations (tables and indexes) for which
956-
free space will be tracked in the shared free-space map. Roughly
957-
seventy bytes of shared memory are consumed for each slot.
958-
The default is one thousand relations.
959-
This parameter can only be set at server start.
960-
</para>
961-
</listitem>
962-
</varlistentry>
963-
964-
</variablelist>
965-
966-
<note>
967-
<para>
968-
See the <xref linkend="sql-vacuum" endterm="sql-vacuum-title">
969-
command for information on setting this parameter.
970-
</para>
971-
</note>
972-
973899
</sect2>
974900

975901
<sect2 id="runtime-config-resource-kernel">

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