* POSTGRES free space map for quickly finding free space in relations
*
*
- * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/storage/freespace.h,v 1.22 2006/09/21 20:31:22 tgl Exp $
+ * src/include/storage/freespace.h
*
*-------------------------------------------------------------------------
*/
#ifndef FREESPACE_H_
#define FREESPACE_H_
+#include "storage/block.h"
+#include "storage/bufpage.h"
#include "storage/relfilenode.h"
-#include "storage/itemptr.h"
+#include "utils/relcache.h"
-
-/*
- * exported types
- */
-typedef struct PageFreeSpaceInfo
-{
- BlockNumber blkno; /* which page in relation */
- Size avail; /* space available on this page */
-} PageFreeSpaceInfo;
-
-
-/* Initial value for average-request moving average */
-#define INITIAL_AVERAGE ((Size) (BLCKSZ / 32))
-
-/*
- * Number of pages and bytes per allocation chunk. Indexes can squeeze 50%
- * more pages into the same space because they don't need to remember how much
- * free space on each page. The nominal number of pages, CHUNKPAGES, is for
- * regular rels, and INDEXCHUNKPAGES is for indexes. CHUNKPAGES should be
- * even so that no space is wasted in the index case.
- */
-#define CHUNKPAGES 16
-#define CHUNKBYTES (CHUNKPAGES * sizeof(FSMPageData))
-#define INDEXCHUNKPAGES ((int) (CHUNKBYTES / sizeof(IndexFSMPageData)))
-
-
-/*
- * Typedefs and macros for items in the page-storage arena. We use the
- * existing ItemPointer and BlockId data structures, which are designed
- * to pack well (they should be 6 and 4 bytes apiece regardless of machine
- * alignment issues). Unfortunately we can't use the ItemPointer access
- * macros, because they include Asserts insisting that ip_posid != 0.
- */
-typedef ItemPointerData FSMPageData;
-typedef BlockIdData IndexFSMPageData;
-
-#define FSMPageGetPageNum(ptr) \
- BlockIdGetBlockNumber(&(ptr)->ip_blkid)
-#define FSMPageGetSpace(ptr) \
- ((Size) (ptr)->ip_posid)
-#define FSMPageSetPageNum(ptr, pg) \
- BlockIdSet(&(ptr)->ip_blkid, pg)
-#define FSMPageSetSpace(ptr, sz) \
- ((ptr)->ip_posid = (OffsetNumber) (sz))
-#define IndexFSMPageGetPageNum(ptr) \
- BlockIdGetBlockNumber(ptr)
-#define IndexFSMPageSetPageNum(ptr, pg) \
- BlockIdSet(ptr, pg)
-
-/*
- * Shared free-space-map objects
- *
- * The per-relation objects are indexed by a hash table, and are also members
- * of two linked lists: one ordered by recency of usage (most recent first),
- * and the other ordered by physical location of the associated storage in
- * the page-info arena.
- *
- * Each relation owns one or more chunks of per-page storage in the "arena".
- * The chunks for each relation are always consecutive, so that it can treat
- * its page storage as a simple array. We further insist that its page data
- * be ordered by block number, so that binary search is possible.
- *
- * Note: we handle pointers to these items as pointers, not as SHMEM_OFFSETs.
- * This assumes that all processes accessing the map will have the shared
- * memory segment mapped at the same place in their address space.
- */
-typedef struct FSMHeader FSMHeader;
-typedef struct FSMRelation FSMRelation;
-
-/* Header for whole map */
-struct FSMHeader
-{
- FSMRelation *usageList; /* FSMRelations in usage-recency order */
- FSMRelation *usageListTail; /* tail of usage-recency list */
- FSMRelation *firstRel; /* FSMRelations in arena storage order */
- FSMRelation *lastRel; /* tail of storage-order list */
- int numRels; /* number of FSMRelations now in use */
- double sumRequests; /* sum of requested chunks over all rels */
- char *arena; /* arena for page-info storage */
- int totalChunks; /* total size of arena, in chunks */
- int usedChunks; /* # of chunks assigned */
- /* NB: there are totalChunks - usedChunks free chunks at end of arena */
-};
-
-/*
- * Per-relation struct --- this is an entry in the shared hash table.
- * The hash key is the RelFileNode value (hence, we look at the physical
- * relation ID, not the logical ID, which is appropriate).
- */
-struct FSMRelation
-{
- RelFileNode key; /* hash key (must be first) */
- FSMRelation *nextUsage; /* next rel in usage-recency order */
- FSMRelation *priorUsage; /* prior rel in usage-recency order */
- FSMRelation *nextPhysical; /* next rel in arena-storage order */
- FSMRelation *priorPhysical; /* prior rel in arena-storage order */
- bool isIndex; /* if true, we store only page numbers */
- Size avgRequest; /* moving average of space requests */
- BlockNumber interestingPages; /* # of pages with useful free space */
- int firstChunk; /* chunk # of my first chunk in arena */
- int storedPages; /* # of pages stored in arena */
- int nextPage; /* index (from 0) to start next search at */
-};
-
-
-
-/* GUC variables */
-extern int MaxFSMRelations;
-extern int MaxFSMPages;
-
-
-/*
- * function prototypes
- */
-extern void InitFreeSpaceMap(void);
-extern Size FreeSpaceShmemSize(void);
-extern FSMHeader *GetFreeSpaceMap(void);
-
-extern BlockNumber GetPageWithFreeSpace(RelFileNode *rel, Size spaceNeeded);
-extern BlockNumber RecordAndGetPageWithFreeSpace(RelFileNode *rel,
+/* prototypes for public functions in freespace.c */
+extern Size GetRecordedFreeSpace(Relation rel, BlockNumber heapBlk);
+extern BlockNumber GetPageWithFreeSpace(Relation rel, Size spaceNeeded);
+extern BlockNumber RecordAndGetPageWithFreeSpace(Relation rel,
BlockNumber oldPage,
Size oldSpaceAvail,
Size spaceNeeded);
-extern Size GetAvgFSMRequestSize(RelFileNode *rel);
-extern void RecordRelationFreeSpace(RelFileNode *rel,
- BlockNumber interestingPages,
- int nPages,
- PageFreeSpaceInfo *pageSpaces);
-
-extern BlockNumber GetFreeIndexPage(RelFileNode *rel);
-extern void RecordIndexFreeSpace(RelFileNode *rel,
- BlockNumber interestingPages,
- int nPages,
- BlockNumber *pages);
-
-extern void FreeSpaceMapTruncateRel(RelFileNode *rel, BlockNumber nblocks);
-extern void FreeSpaceMapForgetRel(RelFileNode *rel);
-extern void FreeSpaceMapForgetDatabase(Oid dbid);
-
-extern void PrintFreeSpaceMapStatistics(int elevel);
-
-extern void DumpFreeSpaceMap(int code, Datum arg);
-extern void LoadFreeSpaceMap(void);
+extern void RecordPageWithFreeSpace(Relation rel, BlockNumber heapBlk,
+ Size spaceAvail);
+extern void XLogRecordPageWithFreeSpace(RelFileNode rnode, BlockNumber heapBlk,
+ Size spaceAvail);
-#ifdef FREESPACE_DEBUG
-extern void DumpFreeSpace(void);
-#endif
+extern void FreeSpaceMapTruncateRel(Relation rel, BlockNumber nblocks);
+extern void FreeSpaceMapVacuum(Relation rel);
-#endif /* FREESPACE_H */
+#endif /* FREESPACE_H_ */
projects / postgresql / blobdiff