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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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97
src/backend/access/spgist/spgscan.c
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@@ -55,7 +55,10 @@ freeScanStack(SpGistScanOpaque so)
so->scanStack = NIL;
}
/* Initialize scanStack with a single entry for the root page */
/*
* Initialize scanStack with a single entry for the root page, resetting
* any previously active scan
*/
static void
resetSpGistScanOpaque(SpGistScanOpaque so)
{
@@ -65,7 +68,16 @@ resetSpGistScanOpaque(SpGistScanOpaque so)
freeScanStack(so);
so->scanStack = list_make1(startEntry);
so->nPtrs = so->iPtr = 0;
if (so->want_itup)
{
/* Must pfree IndexTuples to avoid memory leak */
int i;
for (i = 0; i < so->nPtrs; i++)
pfree(so->indexTups[i]);
}
so->iPtr = so->nPtrs = 0;
}
Datum
@@ -87,6 +99,10 @@ spgbeginscan(PG_FUNCTION_ARGS)
ALLOCSET_DEFAULT_INITSIZE,
ALLOCSET_DEFAULT_MAXSIZE);
resetSpGistScanOpaque(so);
/* Set up indexTupDesc and xs_itupdesc in case it's an index-only scan */
so->indexTupDesc = scan->xs_itupdesc = RelationGetDescr(rel);
scan->opaque = so;
PG_RETURN_POINTER(scan);
@@ -138,28 +154,35 @@ spgrestrpos(PG_FUNCTION_ARGS)
/*
* Test whether a leaf datum satisfies all the scan keys
*
* *leafValue is set to the reconstructed datum, if provided
* *recheck is set true if any of the operators are lossy
*/
static bool
spgLeafTest(SpGistScanOpaque so, Datum leafDatum,
spgLeafTest(Relation index, SpGistScanOpaque so, Datum leafDatum,
int level, Datum reconstructedValue,
bool *recheck)
Datum *leafValue, bool *recheck)
{
bool result = true;
spgLeafConsistentIn in;
spgLeafConsistentOut out;
FmgrInfo *procinfo;
MemoryContext oldCtx;
int i;
*leafValue = (Datum) 0;
*recheck = false;
/* set up values that are the same for all quals */
in.reconstructedValue = reconstructedValue;
in.level = level;
in.returnData = so->want_itup;
in.leafDatum = leafDatum;
/* Apply each leaf consistent function, working in the temp context */
/* Apply each leaf consistency check, working in the temp context */
oldCtx = MemoryContextSwitchTo(so->tempCxt);
procinfo = index_getprocinfo(index, 1, SPGIST_LEAF_CONSISTENT_PROC);
for (i = 0; i < so->numberOfKeys; i++)
{
ScanKey skey = &so->keyData[i];
@@ -174,12 +197,14 @@ spgLeafTest(SpGistScanOpaque so, Datum leafDatum,
in.strategy = skey->sk_strategy;
in.query = skey->sk_argument;
out.leafValue = (Datum) 0;
out.recheck = false;
result = DatumGetBool(FunctionCall2Coll(&so->state.leafConsistentFn,
result = DatumGetBool(FunctionCall2Coll(procinfo,
skey->sk_collation,
PointerGetDatum(&in),
PointerGetDatum(&out)));
*leafValue = out.leafValue;
*recheck |= out.recheck;
if (!result)
break;
@@ -198,7 +223,7 @@ spgLeafTest(SpGistScanOpaque so, Datum leafDatum,
*/
static void
spgWalk(Relation index, SpGistScanOpaque so, bool scanWholeIndex,
void (*storeRes) (SpGistScanOpaque, ItemPointer, bool))
void (*storeRes) (SpGistScanOpaque, ItemPointer, Datum, bool))
{
Buffer buffer = InvalidBuffer;
bool reportedSome = false;
@@ -243,6 +268,7 @@ redirect:
{
SpGistLeafTuple leafTuple;
OffsetNumber max = PageGetMaxOffsetNumber(page);
Datum leafValue = (Datum) 0;
bool recheck = false;
if (blkno == SPGIST_HEAD_BLKNO)
@@ -260,13 +286,14 @@ redirect:
}
Assert(ItemPointerIsValid(&leafTuple->heapPtr));
if (spgLeafTest(so,
if (spgLeafTest(index, so,
SGLTDATUM(leafTuple, &so->state),
stackEntry->level,
stackEntry->reconstructedValue,
&leafValue,
&recheck))
{
storeRes(so, &leafTuple->heapPtr, recheck);
storeRes(so, &leafTuple->heapPtr, leafValue, recheck);
reportedSome = true;
}
}
@@ -304,13 +331,14 @@ redirect:
}
Assert(ItemPointerIsValid(&leafTuple->heapPtr));
if (spgLeafTest(so,
if (spgLeafTest(index, so,
SGLTDATUM(leafTuple, &so->state),
stackEntry->level,
stackEntry->reconstructedValue,
&leafValue,
&recheck))
{
storeRes(so, &leafTuple->heapPtr, recheck);
storeRes(so, &leafTuple->heapPtr, leafValue, recheck);
reportedSome = true;
}
@@ -374,6 +402,7 @@ redirect:
{
spgInnerConsistentIn in;
spgInnerConsistentOut out;
FmgrInfo *procinfo;
SpGistNodeTuple *nodes;
int *andMap;
int *levelAdds;
@@ -388,6 +417,7 @@ redirect:
/* set up values that are the same for all scankeys */
in.reconstructedValue = stackEntry->reconstructedValue;
in.level = stackEntry->level;
in.returnData = so->want_itup;
in.allTheSame = innerTuple->allTheSame;
in.hasPrefix = (innerTuple->prefixSize > 0);
in.prefixDatum = SGITDATUM(innerTuple, &so->state);
@@ -405,6 +435,8 @@ redirect:
levelAdds = (int *) palloc0(sizeof(int) * in.nNodes);
reconstructedValues = (Datum *) palloc0(sizeof(Datum) * in.nNodes);
procinfo = index_getprocinfo(index, 1, SPGIST_INNER_CONSISTENT_PROC);
for (j = 0; j < so->numberOfKeys; j++)
{
ScanKey skey = &so->keyData[j];
@@ -421,7 +453,7 @@ redirect:
memset(&out, 0, sizeof(out));
FunctionCall2Coll(&so->state.innerConsistentFn,
FunctionCall2Coll(procinfo,
skey->sk_collation,
PointerGetDatum(&in),
PointerGetDatum(&out));
@@ -490,7 +522,8 @@ redirect:
/* storeRes subroutine for getbitmap case */
static void
storeBitmap(SpGistScanOpaque so, ItemPointer heapPtr, bool recheck)
storeBitmap(SpGistScanOpaque so, ItemPointer heapPtr,
Datum leafValue, bool recheck)
{
tbm_add_tuples(so->tbm, heapPtr, 1, recheck);
so->ntids++;
@@ -506,6 +539,8 @@ spggetbitmap(PG_FUNCTION_ARGS)
/* Copy scankey to *so so we don't need to pass it around separately */
so->numberOfKeys = scan->numberOfKeys;
so->keyData = scan->keyData;
/* Ditto for the want_itup flag */
so->want_itup = false;
so->tbm = tbm;
so->ntids = 0;
@@ -517,11 +552,24 @@ spggetbitmap(PG_FUNCTION_ARGS)
/* storeRes subroutine for gettuple case */
static void
storeGettuple(SpGistScanOpaque so, ItemPointer heapPtr, bool recheck)
storeGettuple(SpGistScanOpaque so, ItemPointer heapPtr,
Datum leafValue, bool recheck)
{
Assert(so->nPtrs < MaxIndexTuplesPerPage);
so->heapPtrs[so->nPtrs] = *heapPtr;
so->recheck[so->nPtrs] = recheck;
if (so->want_itup)
{
/*
* Reconstruct desired IndexTuple. We have to copy the datum out of
* the temp context anyway, so we may as well create the tuple here.
*/
bool isnull = false;
so->indexTups[so->nPtrs] = index_form_tuple(so->indexTupDesc,
&leafValue,
&isnull);
}
so->nPtrs++;
}
@@ -538,6 +586,8 @@ spggettuple(PG_FUNCTION_ARGS)
/* Copy scankey to *so so we don't need to pass it around separately */
so->numberOfKeys = scan->numberOfKeys;
so->keyData = scan->keyData;
/* Ditto for the want_itup flag */
so->want_itup = scan->xs_want_itup;
for (;;)
{
@@ -546,11 +596,21 @@ spggettuple(PG_FUNCTION_ARGS)
/* continuing to return tuples from a leaf page */
scan->xs_ctup.t_self = so->heapPtrs[so->iPtr];
scan->xs_recheck = so->recheck[so->iPtr];
scan->xs_itup = so->indexTups[so->iPtr];
so->iPtr++;
PG_RETURN_BOOL(true);
}
if (so->want_itup)
{
/* Must pfree IndexTuples to avoid memory leak */
int i;
for (i = 0; i < so->nPtrs; i++)
pfree(so->indexTups[i]);
}
so->iPtr = so->nPtrs = 0;
spgWalk(scan->indexRelation, so, false, storeGettuple);
if (so->nPtrs == 0)
@@ -563,6 +623,11 @@ spggettuple(PG_FUNCTION_ARGS)
Datum
spgcanreturn(PG_FUNCTION_ARGS)
{
/* Not implemented yet */
PG_RETURN_BOOL(false);
Relation index = (Relation) PG_GETARG_POINTER(0);
SpGistCache *cache;
/* We can do it if the opclass config function says so */
cache = spgGetCache(index);
PG_RETURN_BOOL(cache->config.canReturnData);
}