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Add support for index-only scans in GiST.

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This adds a new GiST opclass method, 'fetch', which is used to reconstruct
the original Datum from the value stored in the index. Also, the 'canreturn'
index AM interface function gains a new 'attno' argument. That makes it
possible to use index-only scans on a multi-column index where some of the
opclasses support index-only scans but some do not.

This patch adds support in the box and point opclasses. Other opclasses
can added later as follow-on patches (btree_gist would be particularly
interesting).

Anastasia Lubennikova, with additional fixes and modifications by me.
This commit is contained in:
Heikki Linnakangas
2015-03-26 19:12:00 +02:00
parent 8fa393a6d7
commit d04c8ed904
24 changed files with 575 additions and 73 deletions
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9
src/include/access/gist_private.h
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@@ -87,6 +87,7 @@ typedef struct GISTSTATE
FmgrInfo picksplitFn[INDEX_MAX_KEYS];
FmgrInfo equalFn[INDEX_MAX_KEYS];
FmgrInfo distanceFn[INDEX_MAX_KEYS];
FmgrInfo fetchFn[INDEX_MAX_KEYS];
/* Collations to pass to the support functions */
Oid supportCollation[INDEX_MAX_KEYS];
@@ -118,6 +119,8 @@ typedef struct GISTSearchHeapItem
{
ItemPointerData heapPtr;
bool recheck; /* T if quals must be rechecked */
IndexTuple ftup; /* data fetched back from the index, used in
* index-only scans */
} GISTSearchHeapItem;
/* Unvisited item, either index page or heap tuple */
@@ -157,6 +160,8 @@ typedef struct GISTScanOpaqueData
GISTSearchHeapItem pageData[BLCKSZ / sizeof(IndexTupleData)];
OffsetNumber nPageData; /* number of valid items in array */
OffsetNumber curPageData; /* next item to return */
MemoryContext pageDataCxt; /* context holding the fetched tuples, for
index-only scans */
} GISTScanOpaqueData;
typedef GISTScanOpaqueData *GISTScanOpaque;
@@ -409,6 +414,7 @@ typedef struct GiSTOptions
/* gist.c */
extern Datum gistbuildempty(PG_FUNCTION_ARGS);
extern Datum gistinsert(PG_FUNCTION_ARGS);
extern Datum gistcanreturn(PG_FUNCTION_ARGS);
extern MemoryContext createTempGistContext(void);
extern GISTSTATE *initGISTstate(Relation index);
extern void freeGISTstate(GISTSTATE *giststate);
@@ -504,7 +510,8 @@ extern void gistMakeUnionItVec(GISTSTATE *giststate, IndexTuple *itvec, int len,
extern bool gistKeyIsEQ(GISTSTATE *giststate, int attno, Datum a, Datum b);
extern void gistDeCompressAtt(GISTSTATE *giststate, Relation r, IndexTuple tuple, Page p,
OffsetNumber o, GISTENTRY *attdata, bool *isnull);
extern IndexTuple gistFetchTuple(GISTSTATE *giststate, Relation r,
IndexTuple tuple);
extern void gistMakeUnionKey(GISTSTATE *giststate, int attno,
GISTENTRY *entry1, bool isnull1,
GISTENTRY *entry2, bool isnull2,