diff options
Diffstat (limited to 'src/include')
| -rw-r--r-- | src/include/storage/freespace.h | 99 |
1 files changed, 98 insertions, 1 deletions
diff --git a/src/include/storage/freespace.h b/src/include/storage/freespace.h index 1ce7b7f08ae..9925793b4fa 100644 --- a/src/include/storage/freespace.h +++ b/src/include/storage/freespace.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/include/storage/freespace.h,v 1.18 2005/08/20 23:26:33 tgl Exp $ + * $PostgreSQL: pgsql/src/include/storage/freespace.h,v 1.19 2006/02/12 03:55:53 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -16,6 +16,7 @@ #include "storage/block.h" #include "storage/relfilenode.h" +#include "storage/itemptr.h" /* @@ -28,6 +29,101 @@ typedef struct PageFreeSpaceInfo } 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 */ + int lastPageCount; /* pages passed to RecordRelationFreeSpace */ + 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; @@ -62,6 +158,7 @@ extern void PrintFreeSpaceMapStatistics(int elevel); extern void DumpFreeSpaceMap(int code, Datum arg); extern void LoadFreeSpaceMap(void); +extern FSMHeader *GetFreeSpaceMap(void); #ifdef FREESPACE_DEBUG extern void DumpFreeSpace(void); |