diff options
Diffstat (limited to 'src/backend/access/gin/ginentrypage.c')
| -rw-r--r-- | src/backend/access/gin/ginentrypage.c | 53 |
1 files changed, 40 insertions, 13 deletions
diff --git a/src/backend/access/gin/ginentrypage.c b/src/backend/access/gin/ginentrypage.c index e16575bc813..f35994db953 100644 --- a/src/backend/access/gin/ginentrypage.c +++ b/src/backend/access/gin/ginentrypage.c @@ -8,7 +8,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/access/gin/ginentrypage.c,v 1.19 2009/01/01 17:23:34 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/access/gin/ginentrypage.c,v 1.20 2009/06/06 02:39:40 tgl Exp $ *------------------------------------------------------------------------- */ @@ -20,28 +20,33 @@ #include "utils/rel.h" /* - * forms tuple for entry tree. On leaf page, Index tuple has - * non-traditional layout. Tuple may contain posting list or - * root blocknumber of posting tree. Macros GinIsPostingTre: (itup) / GinSetPostingTree(itup, blkno) + * Form a tuple for entry tree. + * + * On leaf pages, Index tuple has non-traditional layout. Tuple may contain + * posting list or root blocknumber of posting tree. + * Macros: GinIsPostingTree(itup) / GinSetPostingTree(itup, blkno) * 1) Posting list - * - itup->t_info & INDEX_SIZE_MASK contains size of tuple as usual + * - itup->t_info & INDEX_SIZE_MASK contains total size of tuple as usual * - ItemPointerGetBlockNumber(&itup->t_tid) contains original * size of tuple (without posting list). - * Macroses: GinGetOrigSizePosting(itup) / GinSetOrigSizePosting(itup,n) + * Macros: GinGetOrigSizePosting(itup) / GinSetOrigSizePosting(itup,n) * - ItemPointerGetOffsetNumber(&itup->t_tid) contains number - * of elements in posting list (number of heap itempointer) - * Macroses: GinGetNPosting(itup) / GinSetNPosting(itup,n) - * - After usual part of tuple there is a posting list + * of elements in posting list (number of heap itempointers) + * Macros: GinGetNPosting(itup) / GinSetNPosting(itup,n) + * - After standard part of tuple there is a posting list, ie, array + * of heap itempointers * Macros: GinGetPosting(itup) * 2) Posting tree * - itup->t_info & INDEX_SIZE_MASK contains size of tuple as usual * - ItemPointerGetBlockNumber(&itup->t_tid) contains block number of * root of posting tree - * - ItemPointerGetOffsetNumber(&itup->t_tid) contains magic number GIN_TREE_POSTING + * - ItemPointerGetOffsetNumber(&itup->t_tid) contains magic number + * GIN_TREE_POSTING, which distinguishes this from posting-list case * - * Storage of attributes of tuple are different for single and multicolumn index. - * For single-column index tuple stores only value to be indexed and for - * multicolumn variant it stores two attributes: column number of value and value. + * Attributes of an index tuple are different for single and multicolumn index. + * For single-column case, index tuple stores only value to be indexed. + * For multicolumn case, it stores two attributes: column number of value + * and value. */ IndexTuple GinFormTuple(GinState *ginstate, OffsetNumber attnum, Datum key, ItemPointerData *ipd, uint32 nipd) @@ -90,6 +95,28 @@ GinFormTuple(GinState *ginstate, OffsetNumber attnum, Datum key, ItemPointerData } /* + * Sometimes we reduce the number of posting list items in a tuple after + * having built it with GinFormTuple. This function adjusts the size + * fields to match. + */ +void +GinShortenTuple(IndexTuple itup, uint32 nipd) +{ + uint32 newsize; + + Assert(nipd <= GinGetNPosting(itup)); + + newsize = MAXALIGN(SHORTALIGN(GinGetOrigSizePosting(itup)) + sizeof(ItemPointerData) * nipd); + + Assert(newsize <= (itup->t_info & INDEX_SIZE_MASK)); + + itup->t_info &= ~INDEX_SIZE_MASK; + itup->t_info |= newsize; + + GinSetNPosting(itup, nipd); +} + +/* * Entry tree is a "static", ie tuple never deletes from it, * so we don't use right bound, we use rightest key instead. */ |