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Support GiST index support functions that want to cache data across calls.

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pg_trgm was already doing this unofficially, but the implementation hadn't
been thought through very well and leaked memory.  Restructure the core
GiST code so that it actually works, and document it.  Ordinarily this
would have required an extra memory context creation/destruction for each
GiST index search, but I was able to avoid that in the normal case of a
non-rescanned search by finessing the handling of the RBTree.  It used to
have its own context always, but now shares a context with the
scan-lifespan data structures, unless there is more than one rescan call.
This should make the added overhead unnoticeable in typical cases.
This commit is contained in:
Tom Lane
2011-09-30 19:48:57 -04:00
parent 79edb2b1dc
commit d22a09dc70
6 changed files with 206 additions and 82 deletions
doc/src/sgml
gist.sgml
src
backend
access
gist
gist.cgistbuild.cgistget.cgistscan.c
include
access
gist_private.h

42
src/backend/access/gist/gistbuild.c

@ -54,7 +54,7 @@ typedef enum
typedef struct
{
Relation indexrel;
GISTSTATE giststate;
GISTSTATE *giststate;
GISTBuildBuffers *gfbb;
int64 indtuples; /* number of tuples indexed */
@ -63,7 +63,6 @@ typedef struct
Size freespace; /* amount of free space to leave on pages */
GistBufferingMode bufferingMode;
MemoryContext tmpCtx;
} GISTBuildState;
static void gistInitBuffering(GISTBuildState *buildstate);
@ -146,7 +145,14 @@ gistbuild(PG_FUNCTION_ARGS)
RelationGetRelationName(index));
/* no locking is needed */
initGISTstate(&buildstate.giststate, index);
buildstate.giststate = initGISTstate(index);
/*
* Create a temporary memory context that is reset once for each tuple
* processed. (Note: we don't bother to make this a child of the
* giststate's scanCxt, so we have to delete it separately at the end.)
*/
buildstate.giststate->tempCxt = createTempGistContext();
/* initialize the root page */
buffer = gistNewBuffer(index);
@ -184,12 +190,6 @@ gistbuild(PG_FUNCTION_ARGS)
buildstate.indtuples = 0;
buildstate.indtuplesSize = 0;
/*
* create a temporary memory context that is reset once for each tuple
* processed.
*/
buildstate.tmpCtx = createTempGistContext();
/*
* Do the heap scan.
*/
@ -208,9 +208,9 @@ gistbuild(PG_FUNCTION_ARGS)
/* okay, all heap tuples are indexed */
MemoryContextSwitchTo(oldcxt);
MemoryContextDelete(buildstate.tmpCtx);
MemoryContextDelete(buildstate.giststate->tempCxt);
freeGISTstate(&buildstate.giststate);
freeGISTstate(buildstate.giststate);
/*
* Return statistics
@ -440,10 +440,10 @@ gistBuildCallback(Relation index,
IndexTuple itup;
MemoryContext oldCtx;
oldCtx = MemoryContextSwitchTo(buildstate->tmpCtx);
oldCtx = MemoryContextSwitchTo(buildstate->giststate->tempCxt);
/* form an index tuple and point it at the heap tuple */
itup = gistFormTuple(&buildstate->giststate, index, values, isnull, true);
itup = gistFormTuple(buildstate->giststate, index, values, isnull, true);
itup->t_tid = htup->t_self;
if (buildstate->bufferingMode == GIST_BUFFERING_ACTIVE)
@ -458,7 +458,7 @@ gistBuildCallback(Relation index,
* locked, we call gistdoinsert directly.
*/
gistdoinsert(index, itup, buildstate->freespace,
&buildstate->giststate);
buildstate->giststate);
}
/* Update tuple count and total size. */
@ -466,7 +466,7 @@ gistBuildCallback(Relation index,
buildstate->indtuplesSize += IndexTupleSize(itup);
MemoryContextSwitchTo(oldCtx);
MemoryContextReset(buildstate->tmpCtx);
MemoryContextReset(buildstate->giststate->tempCxt);
if (buildstate->bufferingMode == GIST_BUFFERING_ACTIVE &&
buildstate->indtuples % BUFFERING_MODE_TUPLE_SIZE_STATS_TARGET == 0)
@ -520,7 +520,7 @@ static bool
gistProcessItup(GISTBuildState *buildstate, IndexTuple itup,
GISTBufferingInsertStack *startparent)
{
GISTSTATE *giststate = &buildstate->giststate;
GISTSTATE *giststate = buildstate->giststate;
GISTBuildBuffers *gfbb = buildstate->gfbb;
Relation indexrel = buildstate->indexrel;
GISTBufferingInsertStack *path;
@ -652,7 +652,7 @@ gistbufferinginserttuples(GISTBuildState *buildstate, Buffer buffer,
is_split = gistplacetopage(buildstate->indexrel,
buildstate->freespace,
&buildstate->giststate,
buildstate->giststate,
buffer,
itup, ntup, oldoffnum,
InvalidBuffer,
@ -720,7 +720,7 @@ gistbufferinginserttuples(GISTBuildState *buildstate, Buffer buffer,
* buffers that will eventually be inserted to them.
*/
gistRelocateBuildBuffersOnSplit(gfbb,
&buildstate->giststate,
buildstate->giststate,
buildstate->indexrel,
path, buffer, splitinfo);
@ -919,7 +919,7 @@ gistProcessEmptyingQueue(GISTBuildState *buildstate)
}
/* Free all the memory allocated during index tuple processing */
MemoryContextReset(CurrentMemoryContext);
MemoryContextReset(buildstate->giststate->tempCxt);
}
}
}
@ -938,7 +938,7 @@ gistEmptyAllBuffers(GISTBuildState *buildstate)
MemoryContext oldCtx;
int i;
oldCtx = MemoryContextSwitchTo(buildstate->tmpCtx);
oldCtx = MemoryContextSwitchTo(buildstate->giststate->tempCxt);
/*
* Iterate through the levels from top to bottom.
@ -970,7 +970,7 @@ gistEmptyAllBuffers(GISTBuildState *buildstate)
nodeBuffer->queuedForEmptying = true;
gfbb->bufferEmptyingQueue =
lcons(nodeBuffer, gfbb->bufferEmptyingQueue);
MemoryContextSwitchTo(buildstate->tmpCtx);
MemoryContextSwitchTo(buildstate->giststate->tempCxt);
}
gistProcessEmptyingQueue(buildstate);
}