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Push index operator lossiness determination down to GIST/GIN opclass

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"consistent" functions, and remove pg_amop.opreqcheck, as per recent
discussion.  The main immediate benefit of this is that we no longer need
8.3's ugly hack of requiring @@@ rather than @@ to test weight-using tsquery
searches on GIN indexes.  In future it should be possible to optimize some
other queries better than is done now, by detecting at runtime whether the
index match is exact or not.

Tom Lane, after an idea of Heikki's, and with some help from Teodor.
This commit is contained in:
Tom Lane
2008-04-14 17:05:34 +00:00
parent 10be77c173
commit 9b5c8d45f6
68 changed files with 1023 additions and 785 deletions
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65
src/backend/access/gin/ginget.c
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@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/gin/ginget.c,v 1.12 2008/04/13 19:18:13 tgl Exp $
* $PostgreSQL: pgsql/src/backend/access/gin/ginget.c,v 1.13 2008/04/14 17:05:33 tgl Exp $
*-------------------------------------------------------------------------
*/
@ -343,10 +343,12 @@ entryGetItem(Relation index, GinScanEntry entry)
/*
* Sets key->curItem to new found heap item pointer for one scan key
* returns isFinished!
* Returns isFinished, ie TRUE means we did NOT get a new item pointer!
* Also, *keyrecheck is set true if recheck is needed for this scan key.
*/
static bool
keyGetItem(Relation index, GinState *ginstate, MemoryContext tempCtx, GinScanKey key)
keyGetItem(Relation index, GinState *ginstate, MemoryContext tempCtx,
GinScanKey key, bool *keyrecheck)
{
uint32 i;
GinScanEntry entry;
@ -391,31 +393,36 @@ keyGetItem(Relation index, GinState *ginstate, MemoryContext tempCtx, GinScanKey
return TRUE;
}
if (key->nentries == 1)
{
/* we can do not call consistentFn !! */
key->entryRes[0] = TRUE;
return FALSE;
}
/*
* if key->nentries == 1 then the consistentFn should always succeed,
* but we must call it anyway to find out the recheck status.
*/
/* setting up array for consistentFn */
for (i = 0; i < key->nentries; i++)
{
entry = key->scanEntry + i;
if (entry->isFinished == FALSE && compareItemPointers(&entry->curItem, &key->curItem) == 0)
if (entry->isFinished == FALSE &&
compareItemPointers(&entry->curItem, &key->curItem) == 0)
key->entryRes[i] = TRUE;
else
key->entryRes[i] = FALSE;
}
/*
* Initialize *keyrecheck in case the consistentFn doesn't know it
* should set it. The safe assumption in that case is to force
* recheck.
*/
*keyrecheck = true;
oldCtx = MemoryContextSwitchTo(tempCtx);
res = DatumGetBool(FunctionCall3(
&ginstate->consistentFn,
res = DatumGetBool(FunctionCall4(&ginstate->consistentFn,
PointerGetDatum(key->entryRes),
UInt16GetDatum(key->strategy),
key->query
));
key->query,
PointerGetDatum(keyrecheck)));
MemoryContextSwitchTo(oldCtx);
MemoryContextReset(tempCtx);
} while (!res);
@ -430,24 +437,32 @@ keyGetItem(Relation index, GinState *ginstate, MemoryContext tempCtx, GinScanKey
static bool
scanGetItem(IndexScanDesc scan, ItemPointerData *item, bool *recheck)
{
uint32 i;
GinScanOpaque so = (GinScanOpaque) scan->opaque;
uint32 i;
bool keyrecheck;
/* XXX for the moment, treat all GIN operators as lossy */
*recheck = true;
/*
* We return recheck = true if any of the keyGetItem calls return
* keyrecheck = true. Note that because the second loop might advance
* some keys, this could theoretically be too conservative. In practice
* though, we expect that a consistentFn's recheck result will depend
* only on the operator and the query, so for any one key it should
* stay the same regardless of advancing to new items. So it's not
* worth working harder.
*/
*recheck = false;
ItemPointerSetMin(item);
for (i = 0; i < so->nkeys; i++)
{
GinScanKey key = so->keys + i;
if (keyGetItem(scan->indexRelation, &so->ginstate, so->tempCtx, key) == FALSE)
{
if (compareItemPointers(item, &key->curItem) < 0)
*item = key->curItem;
}
else
if (keyGetItem(scan->indexRelation, &so->ginstate, so->tempCtx,
key, &keyrecheck))
return FALSE; /* finished one of keys */
if (compareItemPointers(item, &key->curItem) < 0)
*item = key->curItem;
*recheck |= keyrecheck;
}
for (i = 1; i <= so->nkeys; i++)
@ -462,8 +477,10 @@ scanGetItem(IndexScanDesc scan, ItemPointerData *item, bool *recheck)
break;
else if (cmp > 0)
{
if (keyGetItem(scan->indexRelation, &so->ginstate, so->tempCtx, key) == TRUE)
if (keyGetItem(scan->indexRelation, &so->ginstate, so->tempCtx,
key, &keyrecheck))
return FALSE; /* finished one of keys */
*recheck |= keyrecheck;
}
else
{ /* returns to begin */