diff options
Diffstat (limited to 'src/include/access/hash.h')
| -rw-r--r-- | src/include/access/hash.h | 69 |
1 files changed, 47 insertions, 22 deletions
diff --git a/src/include/access/hash.h b/src/include/access/hash.h index 7edbdad098..beffa806ea 100644 --- a/src/include/access/hash.h +++ b/src/include/access/hash.h @@ -7,7 +7,7 @@ * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $Id: hash.h,v 1.52 2003/09/02 18:13:32 tgl Exp $ + * $Id: hash.h,v 1.53 2003/09/04 22:06:27 tgl Exp $ * * NOTES * modeled after Margo Seltzer's hash implementation for unix. @@ -70,13 +70,27 @@ typedef HashPageOpaqueData *HashPageOpaque; #define HASHO_FILL 0x1234 /* - * ScanOpaqueData is used to remember which buffers we're currently - * examining in the scan. We keep these buffers locked and pinned and - * recorded in the opaque entry of the scan in order to avoid doing a - * ReadBuffer() for every tuple in the index. + * HashScanOpaqueData is private state for a hash index scan. */ typedef struct HashScanOpaqueData { + /* + * By definition, a hash scan should be examining only one bucket. + * We record the bucket number here as soon as it is known. + */ + Bucket hashso_bucket; + bool hashso_bucket_valid; + /* + * If we have a share lock on the bucket, we record it here. When + * hashso_bucket_blkno is zero, we have no such lock. + */ + BlockNumber hashso_bucket_blkno; + /* + * We also want to remember which buffers we're currently examining in the + * scan. We keep these buffers pinned (but not locked) across hashgettuple + * calls, in order to avoid doing a ReadBuffer() for every tuple in the + * index. + */ Buffer hashso_curbuf; Buffer hashso_mrkbuf; } HashScanOpaqueData; @@ -149,9 +163,17 @@ typedef struct HashItemData typedef HashItemData *HashItem; /* + * Maximum size of a hash index item (it's okay to have only one per page) + */ +#define HashMaxItemSize(page) \ + (PageGetPageSize(page) - \ + sizeof(PageHeaderData) - \ + MAXALIGN(sizeof(HashPageOpaqueData)) - \ + sizeof(ItemIdData)) + +/* * Constants */ -#define DEFAULT_FFACTOR 300 #define BYTE_TO_BIT 3 /* 2^3 bits/byte */ #define ALL_SET ((uint32) ~0) @@ -180,10 +202,14 @@ typedef HashItemData *HashItem; #define ISSET(A, N) ((A)[(N)/BITS_PER_MAP] & (1<<((N)%BITS_PER_MAP))) /* - * page locking modes + * page-level and high-level locking modes (see README) */ -#define HASH_READ 0 -#define HASH_WRITE 1 +#define HASH_READ BUFFER_LOCK_SHARE +#define HASH_WRITE BUFFER_LOCK_EXCLUSIVE +#define HASH_NOLOCK (-1) + +#define HASH_SHARE ShareLock +#define HASH_EXCLUSIVE ExclusiveLock /* * Strategy number. There's only one valid strategy for hashing: equality. @@ -199,8 +225,6 @@ typedef HashItemData *HashItem; #define HASHPROC 1 -extern bool BuildingHash; - /* public routines */ extern Datum hashbuild(PG_FUNCTION_ARGS); @@ -250,36 +274,37 @@ extern void _hash_squeezebucket(Relation rel, Bucket bucket, BlockNumber bucket_blkno); /* hashpage.c */ -extern void _hash_metapinit(Relation rel); +extern void _hash_getlock(Relation rel, BlockNumber whichlock, int access); +extern bool _hash_try_getlock(Relation rel, BlockNumber whichlock, int access); +extern void _hash_droplock(Relation rel, BlockNumber whichlock, int access); extern Buffer _hash_getbuf(Relation rel, BlockNumber blkno, int access); -extern void _hash_relbuf(Relation rel, Buffer buf, int access); +extern void _hash_relbuf(Relation rel, Buffer buf); +extern void _hash_dropbuf(Relation rel, Buffer buf); extern void _hash_wrtbuf(Relation rel, Buffer buf); -extern void _hash_wrtnorelbuf(Buffer buf); +extern void _hash_wrtnorelbuf(Relation rel, Buffer buf); extern void _hash_chgbufaccess(Relation rel, Buffer buf, int from_access, int to_access); +extern void _hash_metapinit(Relation rel); extern void _hash_pageinit(Page page, Size size); extern void _hash_expandtable(Relation rel, Buffer metabuf); /* hashscan.c */ extern void _hash_regscan(IndexScanDesc scan); extern void _hash_dropscan(IndexScanDesc scan); -extern void _hash_adjscans(Relation rel, ItemPointer tid); +extern bool _hash_has_active_scan(Relation rel, Bucket bucket); extern void AtEOXact_hash(void); /* hashsearch.c */ -extern void _hash_search(Relation rel, int keysz, ScanKey scankey, - Buffer *bufP, HashMetaPage metap); extern bool _hash_next(IndexScanDesc scan, ScanDirection dir); extern bool _hash_first(IndexScanDesc scan, ScanDirection dir); -extern bool _hash_step(IndexScanDesc scan, Buffer *bufP, ScanDirection dir, - Buffer metabuf); +extern bool _hash_step(IndexScanDesc scan, Buffer *bufP, ScanDirection dir); /* hashutil.c */ -extern ScanKey _hash_mkscankey(Relation rel, IndexTuple itup); -extern void _hash_freeskey(ScanKey skey); extern bool _hash_checkqual(IndexScanDesc scan, IndexTuple itup); extern HashItem _hash_formitem(IndexTuple itup); -extern Bucket _hash_call(Relation rel, HashMetaPage metap, Datum key); +extern uint32 _hash_datum2hashkey(Relation rel, Datum key); +extern Bucket _hash_hashkey2bucket(uint32 hashkey, uint32 maxbucket, + uint32 highmask, uint32 lowmask); extern uint32 _hash_log2(uint32 num); extern void _hash_checkpage(Relation rel, Page page, int flags); |