diff options
Diffstat (limited to 'src/include/access/hash.h')
| -rw-r--r-- | src/include/access/hash.h | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/src/include/access/hash.h b/src/include/access/hash.h index 1a9b91f9f53..c0455851f46 100644 --- a/src/include/access/hash.h +++ b/src/include/access/hash.h @@ -61,10 +61,21 @@ typedef uint32 Bucket; #define LH_PAGE_TYPE \ (LH_OVERFLOW_PAGE|LH_BUCKET_PAGE|LH_BITMAP_PAGE|LH_META_PAGE) +/* + * In an overflow page, hasho_prevblkno stores the block number of the previous + * page in the bucket chain; in a bucket page, hasho_prevblkno stores the + * hashm_maxbucket value as of the last time the bucket was last split, or + * else as of the time the bucket was created. The latter convention is used + * to determine whether a cached copy of the metapage is too stale to be used + * without needing to lock or pin the metapage. + * + * hasho_nextblkno is always the block number of the next page in the + * bucket chain, or InvalidBlockNumber if there are no more such pages. + */ typedef struct HashPageOpaqueData { - BlockNumber hasho_prevblkno; /* previous ovfl (or bucket) blkno */ - BlockNumber hasho_nextblkno; /* next ovfl blkno */ + BlockNumber hasho_prevblkno; /* see above */ + BlockNumber hasho_nextblkno; /* see above */ Bucket hasho_bucket; /* bucket number this pg belongs to */ uint16 hasho_flag; /* page type code, see above */ uint16 hasho_page_id; /* for identification of hash indexes */ @@ -309,6 +320,11 @@ extern Buffer _hash_getbuf(Relation rel, BlockNumber blkno, int access, int flags); extern Buffer _hash_getbuf_with_condlock_cleanup(Relation rel, BlockNumber blkno, int flags); +extern HashMetaPage _hash_getcachedmetap(Relation rel, Buffer *metabuf, + bool force_refresh); +extern Buffer _hash_getbucketbuf_from_hashkey(Relation rel, uint32 hashkey, + int access, + HashMetaPage *cachedmetap); extern Buffer _hash_getinitbuf(Relation rel, BlockNumber blkno); extern Buffer _hash_getnewbuf(Relation rel, BlockNumber blkno, ForkNumber forkNum); |