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.

3 files changed, 9 insertions, 30 deletions

diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index 7bfb23aaf0..cec75ada72 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.273 2008/08/10 19:02:33 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/cache/relcache.c,v 1.274 2008/09/30 10:52:13 heikki Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -304,6 +304,7 @@ AllocateRelationDesc(Relation relation, Form_pg_class relp)
 	 */
 	MemSet(relation, 0, sizeof(RelationData));
 	relation->rd_targblock = InvalidBlockNumber;
+	relation->rd_fsm_nblocks_cache = InvalidBlockNumber;
 
 	/* make sure relation is marked as having no open file yet */
 	relation->rd_smgr = NULL;
@@ -1364,6 +1365,7 @@ formrdesc(const char *relationName, Oid relationReltype,
 	 */
 	relation = (Relation) palloc0(sizeof(RelationData));
 	relation->rd_targblock = InvalidBlockNumber;
+	relation->rd_fsm_nblocks_cache = InvalidBlockNumber;
 
 	/* make sure relation is marked as having no open file yet */
 	relation->rd_smgr = NULL;
@@ -1652,8 +1654,9 @@ RelationReloadIndexInfo(Relation relation)
 	heap_freetuple(pg_class_tuple);
 	/* We must recalculate physical address in case it changed */
 	RelationInitPhysicalAddr(relation);
-	/* Make sure targblock is reset in case rel was truncated */
+	/* Must reset targblock and fsm_nblocks_cache in case rel was truncated */
 	relation->rd_targblock = InvalidBlockNumber;
+	relation->rd_fsm_nblocks_cache = InvalidBlockNumber;
 	/* Must free any AM cached data, too */
 	if (relation->rd_amcache)
 		pfree(relation->rd_amcache);
@@ -1736,6 +1739,7 @@ RelationClearRelation(Relation relation, bool rebuild)
 	if (relation->rd_isnailed)
 	{
 		relation->rd_targblock = InvalidBlockNumber;
+		relation->rd_fsm_nblocks_cache = InvalidBlockNumber;
 		if (relation->rd_rel->relkind == RELKIND_INDEX)
 		{
 			relation->rd_isvalid = false;		/* needs to be revalidated */
@@ -2330,6 +2334,7 @@ RelationBuildLocalRelation(const char *relname,
 	rel = (Relation) palloc0(sizeof(RelationData));
 
 	rel->rd_targblock = InvalidBlockNumber;
+	rel->rd_fsm_nblocks_cache = InvalidBlockNumber;
 
 	/* make sure relation is marked as having no open file yet */
 	rel->rd_smgr = NULL;
@@ -3586,6 +3591,7 @@ load_relcache_init_file(void)
 		 */
 		rel->rd_smgr = NULL;
 		rel->rd_targblock = InvalidBlockNumber;
+		rel->rd_fsm_nblocks_cache = InvalidBlockNumber;
 		if (rel->rd_isnailed)
 			rel->rd_refcnt = 1;
 		else
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index f0f49538e7..93f20eef35 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -10,7 +10,7 @@
  * Written by Peter Eisentraut <peter_e@gmx.net>.
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.473 2008/09/23 21:12:03 mha Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/misc/guc.c,v 1.474 2008/09/30 10:52:13 heikki Exp $
  *
  *--------------------------------------------------------------------
  */
@@ -57,7 +57,6 @@
 #include "regex/regex.h"
 #include "storage/bufmgr.h"
 #include "storage/fd.h"
-#include "storage/freespace.h"
 #include "tcop/tcopprot.h"
 #include "tsearch/ts_cache.h"
 #include "utils/builtins.h"
@@ -446,8 +445,6 @@ const char *const config_group_names[] =
 	gettext_noop("Resource Usage"),
 	/* RESOURCES_MEM */
 	gettext_noop("Resource Usage / Memory"),
-	/* RESOURCES_FSM */
-	gettext_noop("Resource Usage / Free Space Map"),
 	/* RESOURCES_KERNEL */
 	gettext_noop("Resource Usage / Kernel Resources"),
 	/* WAL */
@@ -1529,23 +1526,6 @@ static struct config_int ConfigureNamesInt[] =
 	},
 
 	{
-		{"max_fsm_relations", PGC_POSTMASTER, RESOURCES_FSM,
-			gettext_noop("Sets the maximum number of tables and indexes for which free space is tracked."),
-			NULL
-		},
-		&MaxFSMRelations,
-		1000, 100, INT_MAX, NULL, NULL
-	},
-	{
-		{"max_fsm_pages", PGC_POSTMASTER, RESOURCES_FSM,
-			gettext_noop("Sets the maximum number of disk pages for which free space is tracked."),
-			NULL
-		},
-		&MaxFSMPages,
-		20000, 1000, INT_MAX, NULL, NULL
-	},
-
-	{
 		{"max_locks_per_transaction", PGC_POSTMASTER, LOCK_MANAGEMENT,
 			gettext_noop("Sets the maximum number of locks per transaction."),
 			gettext_noop("The shared lock table is sized on the assumption that "
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample
index 342be9d6c3..56afb2e488 100644
--- a/src/backend/utils/misc/postgresql.conf.sample
+++ b/src/backend/utils/misc/postgresql.conf.sample
@@ -114,13 +114,6 @@
 #maintenance_work_mem = 16MB		# min 1MB
 #max_stack_depth = 2MB			# min 100kB
 
-# - Free Space Map -
-
-#max_fsm_pages = 204800			# min max_fsm_relations*16, 6 bytes each
-					# (change requires restart)
-#max_fsm_relations = 1000		# min 100, ~70 bytes each
-					# (change requires restart)
-
 # - Kernel Resource Usage -
 
 #max_files_per_process = 1000		# min 25