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Teach SP-GiST to do index-only scans.

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Operator classes can specify whether or not they support this; this
preserves the flexibility to use lossy representations within an index.

In passing, move constant data about a given index into the rd_amcache
cache area, instead of doing fresh lookups each time we start an index
operation.  This is mainly to try to make sure that spgcanreturn() has
insignificant cost; I still don't have any proof that it matters for
actual index accesses.  Also, get rid of useless copying of FmgrInfo
pointers; we can perfectly well use the relcache's versions in-place.
This commit is contained in:
Tom Lane
2011-12-19 14:58:41 -05:00
parent 3695a55513
commit 9220362493
10 changed files with 286 additions and 172 deletions
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31
src/include/access/spgist_private.h
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@@ -71,11 +71,11 @@ typedef struct SpGistLastUsedPage
int freeSpace; /* its free space (could be obsolete!) */
} SpGistLastUsedPage;
typedef struct SpGistCache
typedef struct SpGistLUPCache
{
SpGistLastUsedPage innerPage[3]; /* one per triple-parity group */
SpGistLastUsedPage leafPage;
} SpGistCache;
} SpGistLUPCache;
/*
* metapage
@@ -83,7 +83,7 @@ typedef struct SpGistCache
typedef struct SpGistMetaPageData
{
uint32 magicNumber; /* for identity cross-check */
SpGistCache lastUsedPages; /* shared storage of last-used info */
SpGistLUPCache lastUsedPages; /* shared storage of last-used info */
} SpGistMetaPageData;
#define SPGIST_MAGIC_NUMBER (0xBA0BABED)
@@ -112,12 +112,6 @@ typedef struct SpGistState
SpGistTypeDesc attPrefixType; /* type of inner-tuple prefix values */
SpGistTypeDesc attLabelType; /* type of node label values */
/* lookup data for the opclass support functions, except config */
FmgrInfo chooseFn;
FmgrInfo picksplitFn;
FmgrInfo innerConsistentFn;
FmgrInfo leafConsistentFn;
char *deadTupleStorage; /* workspace for spgFormDeadTuple */
TransactionId myXid; /* XID to use when creating a redirect tuple */
@@ -144,10 +138,13 @@ typedef struct SpGistScanOpaqueData
int64 ntids; /* number of TIDs passed to bitmap */
/* These fields are only used in amgettuple scans: */
bool want_itup; /* are we reconstructing tuples? */
TupleDesc indexTupDesc; /* if so, tuple descriptor for them */
int nPtrs; /* number of TIDs found on current page */
int iPtr; /* index for scanning through same */
ItemPointerData heapPtrs[MaxIndexTuplesPerPage]; /* TIDs from cur page */
bool recheck[MaxIndexTuplesPerPage]; /* their recheck flags */
IndexTuple indexTups[MaxIndexTuplesPerPage]; /* reconstructed tuples */
/*
* Note: using MaxIndexTuplesPerPage above is a bit hokey since
@@ -158,6 +155,21 @@ typedef struct SpGistScanOpaqueData
typedef SpGistScanOpaqueData *SpGistScanOpaque;
/*
* This struct is what we actually keep in index->rd_amcache. It includes
* static configuration information as well as the lastUsedPages cache.
*/
typedef struct SpGistCache
{
spgConfigOut config; /* filled in by opclass config method */
SpGistTypeDesc attType; /* type of input data and leaf values */
SpGistTypeDesc attPrefixType; /* type of inner-tuple prefix values */
SpGistTypeDesc attLabelType; /* type of node label values */
SpGistLUPCache lastUsedPages; /* local storage of last-used info */
} SpGistCache;
/*
* SPGiST tuple types. Note: inner, leaf, and dead tuple structs
@@ -570,6 +582,7 @@ typedef struct spgxlogVacuumRedirect
#define GBUF_INNER_PARITY(x) ((x) % 3)
/* spgutils.c */
extern SpGistCache *spgGetCache(Relation index);
extern void initSpGistState(SpGistState *state, Relation index);
extern Buffer SpGistNewBuffer(Relation index);
extern void SpGistUpdateMetaPage(Relation index);