Restructure SPGiST opclass interface API to support whole-index scans.

The original API definition was incapable of supporting whole-index scans
because there was no way to invoke leaf-value reconstruction without
checking any qual conditions.  Also, it was inefficient for
multiple-qual-condition scans because value reconstruction got done over
again for each qual condition, and because other internal work in the
consistent functions likewise had to be done for each qual.  To fix these
issues, pass the whole scankey array to the opclass consistent functions,
instead of only letting them see one item at a time.  (Essentially, the
loop over scankey entries is now inside the consistent functions not
outside them.  This makes the consistent functions a bit more complicated,
but not unreasonably so.)

In itself this commit does nothing except save a few cycles in
multiple-qual-condition index scans, since we can't support whole-index
scans on SPGiST indexes until nulls are included in the index.  However,
I consider this a must-fix for 9.2 because once we release it will get
very much harder to change the opclass API definition.

1 files changed, 170 insertions, 175 deletions

diff --git a/src/backend/access/spgist/spgscan.c b/src/backend/access/spgist/spgscan.c
index 22cfcc87929..99b0852611f 100644
--- a/src/backend/access/spgist/spgscan.c
+++ b/src/backend/access/spgist/spgscan.c
@@ -56,18 +56,25 @@ freeScanStack(SpGistScanOpaque so)
 }
 
 /*
- * Initialize scanStack with a single entry for the root page, resetting
+ * Initialize scanStack to search the root page, resetting
  * any previously active scan
  */
 static void
 resetSpGistScanOpaque(SpGistScanOpaque so)
 {
-	ScanStackEntry *startEntry = palloc0(sizeof(ScanStackEntry));
-
-	ItemPointerSet(&startEntry->ptr, SPGIST_HEAD_BLKNO, FirstOffsetNumber);
+	ScanStackEntry *startEntry;
 
 	freeScanStack(so);
-	so->scanStack = list_make1(startEntry);
+
+	Assert(!so->searchNulls);	/* XXX fixme */
+
+	if (so->searchNonNulls)
+	{
+		/* Stack a work item to scan the non-null index entries */
+		startEntry = (ScanStackEntry *) palloc0(sizeof(ScanStackEntry));
+		ItemPointerSet(&startEntry->ptr, SPGIST_HEAD_BLKNO, FirstOffsetNumber);
+		so->scanStack = list_make1(startEntry);
+	}
 
 	if (so->want_itup)
 	{
@@ -80,6 +87,82 @@ resetSpGistScanOpaque(SpGistScanOpaque so)
 	so->iPtr = so->nPtrs = 0;
 }
 
+/*
+ * Prepare scan keys in SpGistScanOpaque from caller-given scan keys
+ *
+ * Sets searchNulls, searchNonNulls, numberOfKeys, keyData fields of *so.
+ *
+ * The point here is to eliminate null-related considerations from what the
+ * opclass consistent functions need to deal with.  We assume all SPGiST-
+ * indexable operators are strict, so any null RHS value makes the scan
+ * condition unsatisfiable.  We also pull out any IS NULL/IS NOT NULL
+ * conditions; their effect is reflected into searchNulls/searchNonNulls.
+ */
+static void
+spgPrepareScanKeys(IndexScanDesc scan)
+{
+	SpGistScanOpaque so = (SpGistScanOpaque) scan->opaque;
+	bool		qual_ok;
+	bool		haveIsNull;
+	bool		haveNotNull;
+	int			nkeys;
+	int			i;
+
+	if (scan->numberOfKeys <= 0)
+	{
+		/* If no quals, whole-index scan is required */
+		so->searchNulls = true;
+		so->searchNonNulls = true;
+		so->numberOfKeys = 0;
+		return;
+	}
+
+	/* Examine the given quals */
+	qual_ok = true;
+	haveIsNull = haveNotNull = false;
+	nkeys = 0;
+	for (i = 0; i < scan->numberOfKeys; i++)
+	{
+		ScanKey		skey = &scan->keyData[i];
+
+		if (skey->sk_flags & SK_SEARCHNULL)
+			haveIsNull = true;
+		else if (skey->sk_flags & SK_SEARCHNOTNULL)
+			haveNotNull = true;
+		else if (skey->sk_flags & SK_ISNULL)
+		{
+			/* ordinary qual with null argument - unsatisfiable */
+			qual_ok = false;
+			break;
+		}
+		else
+		{
+			/* ordinary qual, propagate into so->keyData */
+			so->keyData[nkeys++] = *skey;
+			/* this effectively creates a not-null requirement */
+			haveNotNull = true;
+		}
+	}
+
+	/* IS NULL in combination with something else is unsatisfiable */
+	if (haveIsNull && haveNotNull)
+		qual_ok = false;
+
+	/* Emit results */
+	if (qual_ok)
+	{
+		so->searchNulls = haveIsNull;
+		so->searchNonNulls = haveNotNull;
+		so->numberOfKeys = nkeys;
+	}
+	else
+	{
+		so->searchNulls = false;
+		so->searchNonNulls = false;
+		so->numberOfKeys = 0;
+	}
+}
+
 Datum
 spgbeginscan(PG_FUNCTION_ARGS)
 {
@@ -92,13 +175,16 @@ spgbeginscan(PG_FUNCTION_ARGS)
 	scan = RelationGetIndexScan(rel, keysz, 0);
 
 	so = (SpGistScanOpaque) palloc0(sizeof(SpGistScanOpaqueData));
+	if (keysz > 0)
+		so->keyData = (ScanKey) palloc(sizeof(ScanKeyData) * keysz);
+	else
+		so->keyData = NULL;
 	initSpGistState(&so->state, scan->indexRelation);
 	so->tempCxt = AllocSetContextCreate(CurrentMemoryContext,
 										"SP-GiST search temporary context",
 										ALLOCSET_DEFAULT_MINSIZE,
 										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);
@@ -115,12 +201,17 @@ spgrescan(PG_FUNCTION_ARGS)
 	SpGistScanOpaque so = (SpGistScanOpaque) scan->opaque;
 	ScanKey		scankey = (ScanKey) PG_GETARG_POINTER(1);
 
+	/* copy scankeys into local storage */
 	if (scankey && scan->numberOfKeys > 0)
 	{
 		memmove(scan->keyData, scankey,
 				scan->numberOfKeys * sizeof(ScanKeyData));
 	}
 
+	/* preprocess scankeys, set up the representation in *so */
+	spgPrepareScanKeys(scan);
+
+	/* set up starting stack entries */
 	resetSpGistScanOpaque(so);
 
 	PG_RETURN_VOID();
@@ -162,53 +253,34 @@ spgLeafTest(Relation index, SpGistScanOpaque so, Datum leafDatum,
 			int level, Datum reconstructedValue,
 			Datum *leafValue, bool *recheck)
 {
-	bool		result = true;
+	bool		result;
 	spgLeafConsistentIn in;
 	spgLeafConsistentOut out;
 	FmgrInfo   *procinfo;
 	MemoryContext oldCtx;
-	int			i;
 
-	*leafValue = (Datum) 0;
-	*recheck = false;
+	/* use temp context for calling leaf_consistent */
+	oldCtx = MemoryContextSwitchTo(so->tempCxt);
 
-	/* set up values that are the same for all quals */
+	in.scankeys = so->keyData;
+	in.nkeys = so->numberOfKeys;
 	in.reconstructedValue = reconstructedValue;
 	in.level = level;
 	in.returnData = so->want_itup;
 	in.leafDatum = leafDatum;
 
-	/* Apply each leaf consistency check, working in the temp context */
-	oldCtx = MemoryContextSwitchTo(so->tempCxt);
+	out.leafValue = (Datum) 0;
+	out.recheck = false;
 
 	procinfo = index_getprocinfo(index, 1, SPGIST_LEAF_CONSISTENT_PROC);
+	result = DatumGetBool(FunctionCall2Coll(procinfo,
+											index->rd_indcollation[0],
+											PointerGetDatum(&in),
+											PointerGetDatum(&out)));
 
-	for (i = 0; i < so->numberOfKeys; i++)
-	{
-		ScanKey		skey = &so->keyData[i];
-
-		/* Assume SPGiST-indexable operators are strict */
-		if (skey->sk_flags & SK_ISNULL)
-		{
-			result = false;
-			break;
-		}
+	*leafValue = out.leafValue;
+	*recheck = out.recheck;
 
-		in.strategy = skey->sk_strategy;
-		in.query = skey->sk_argument;
-
-		out.leafValue = (Datum) 0;
-		out.recheck = false;
-
-		result = DatumGetBool(FunctionCall2Coll(procinfo,
-												skey->sk_collation,
-												PointerGetDatum(&in),
-												PointerGetDatum(&out)));
-		*leafValue = out.leafValue;
-		*recheck |= out.recheck;
-		if (!result)
-			break;
-	}
 	MemoryContextSwitchTo(oldCtx);
 
 	return result;
@@ -349,8 +421,13 @@ redirect:
 		else	/* page is inner */
 		{
 			SpGistInnerTuple innerTuple;
+			spgInnerConsistentIn in;
+			spgInnerConsistentOut out;
+			FmgrInfo   *procinfo;
+			SpGistNodeTuple *nodes;
 			SpGistNodeTuple node;
 			int			i;
+			MemoryContext oldCtx;
 
 			innerTuple = (SpGistInnerTuple) PageGetItem(page,
 														PageGetItemId(page, offset));
@@ -368,144 +445,68 @@ redirect:
 					 innerTuple->tupstate);
 			}
 
-			if (so->numberOfKeys == 0)
+			/* use temp context for calling inner_consistent */
+			oldCtx = MemoryContextSwitchTo(so->tempCxt);
+
+			in.scankeys = so->keyData;
+			in.nkeys = so->numberOfKeys;
+			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);
+			in.nNodes = innerTuple->nNodes;
+			in.nodeLabels = spgExtractNodeLabels(&so->state, innerTuple);
+
+			/* collect node pointers */
+			nodes = (SpGistNodeTuple *) palloc(sizeof(SpGistNodeTuple) * in.nNodes);
+			SGITITERATE(innerTuple, i, node)
 			{
-				/*
-				 * This case cannot happen at the moment, because we don't
-				 * set pg_am.amoptionalkey for SP-GiST.  In order for full
-				 * index scans to produce correct answers, we'd need to
-				 * index nulls, which we don't.
-				 */
-				Assert(false);
-
-#ifdef NOT_USED
-				/*
-				 * A full index scan could be done approximately like this,
-				 * but note that reconstruction of indexed values would be
-				 * impossible unless the API for inner_consistent is changed.
-				 */
-				SGITITERATE(innerTuple, i, node)
-				{
-					if (ItemPointerIsValid(&node->t_tid))
-					{
-						ScanStackEntry *newEntry = palloc(sizeof(ScanStackEntry));
-
-						newEntry->ptr = node->t_tid;
-						newEntry->level = -1;
-						newEntry->reconstructedValue = (Datum) 0;
-						so->scanStack = lcons(newEntry, so->scanStack);
-					}
-				}
-#endif
+				nodes[i] = node;
 			}
-			else
-			{
-				spgInnerConsistentIn in;
-				spgInnerConsistentOut out;
-				FmgrInfo   *procinfo;
-				SpGistNodeTuple *nodes;
-				int		   *andMap;
-				int		   *levelAdds;
-				Datum	   *reconstructedValues;
-				int			j,
-							nMatches = 0;
-				MemoryContext oldCtx;
-
-				/* use temp context for calling inner_consistent */
-				oldCtx = MemoryContextSwitchTo(so->tempCxt);
-
-				/* 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);
-				in.nNodes = innerTuple->nNodes;
-				in.nodeLabels = spgExtractNodeLabels(&so->state, innerTuple);
-
-				/* collect node pointers */
-				nodes = (SpGistNodeTuple *) palloc(sizeof(SpGistNodeTuple) * in.nNodes);
-				SGITITERATE(innerTuple, i, node)
-				{
-					nodes[i] = node;
-				}
 
-				andMap = (int *) palloc0(sizeof(int) * in.nNodes);
-				levelAdds = (int *) palloc0(sizeof(int) * in.nNodes);
-				reconstructedValues = (Datum *) palloc0(sizeof(Datum) * in.nNodes);
+			memset(&out, 0, sizeof(out));
 
-				procinfo = index_getprocinfo(index, 1, SPGIST_INNER_CONSISTENT_PROC);
+			procinfo = index_getprocinfo(index, 1, SPGIST_INNER_CONSISTENT_PROC);
+			FunctionCall2Coll(procinfo,
+							  index->rd_indcollation[0],
+							  PointerGetDatum(&in),
+							  PointerGetDatum(&out));
 
-				for (j = 0; j < so->numberOfKeys; j++)
-				{
-					ScanKey		skey = &so->keyData[j];
-
-					/* Assume SPGiST-indexable operators are strict */
-					if (skey->sk_flags & SK_ISNULL)
-					{
-						nMatches = 0;
-						break;
-					}
-
-					in.strategy = skey->sk_strategy;
-					in.query = skey->sk_argument;
+			MemoryContextSwitchTo(oldCtx);
 
-					memset(&out, 0, sizeof(out));
-
-					FunctionCall2Coll(procinfo,
-									  skey->sk_collation,
-									  PointerGetDatum(&in),
-									  PointerGetDatum(&out));
-
-					/* If allTheSame, they should all or none of 'em match */
-					if (innerTuple->allTheSame)
-						if (out.nNodes != 0 && out.nNodes != in.nNodes)
-							elog(ERROR, "inconsistent inner_consistent results for allTheSame inner tuple");
-
-					nMatches = 0;
-					for (i = 0; i < out.nNodes; i++)
-					{
-						int		nodeN = out.nodeNumbers[i];
-
-						andMap[nodeN]++;
-						if (andMap[nodeN] == j + 1)
-							nMatches++;
-						if (out.levelAdds)
-							levelAdds[nodeN] = out.levelAdds[i];
-						if (out.reconstructedValues)
-							reconstructedValues[nodeN] = out.reconstructedValues[i];
-					}
+			/* If allTheSame, they should all or none of 'em match */
+			if (innerTuple->allTheSame)
+				if (out.nNodes != 0 && out.nNodes != in.nNodes)
+					elog(ERROR, "inconsistent inner_consistent results for allTheSame inner tuple");
 
-					/* quit as soon as all nodes have failed some qual */
-					if (nMatches == 0)
-						break;
-				}
-
-				MemoryContextSwitchTo(oldCtx);
+			for (i = 0; i < out.nNodes; i++)
+			{
+				int		nodeN = out.nodeNumbers[i];
 
-				if (nMatches > 0)
+				Assert(nodeN >= 0 && nodeN < in.nNodes);
+				if (ItemPointerIsValid(&nodes[nodeN]->t_tid))
 				{
-					for (i = 0; i < in.nNodes; i++)
-					{
-						if (andMap[i] == so->numberOfKeys &&
-							ItemPointerIsValid(&nodes[i]->t_tid))
-						{
-							ScanStackEntry *newEntry;
-
-							/* Create new work item for this node */
-							newEntry = palloc(sizeof(ScanStackEntry));
-							newEntry->ptr = nodes[i]->t_tid;
-							newEntry->level = stackEntry->level + levelAdds[i];
-							/* Must copy value out of temp context */
-							newEntry->reconstructedValue =
-								datumCopy(reconstructedValues[i],
-										  so->state.attType.attbyval,
-										  so->state.attType.attlen);
-
-							so->scanStack = lcons(newEntry, so->scanStack);
-						}
-					}
+					ScanStackEntry *newEntry;
+
+					/* Create new work item for this node */
+					newEntry = palloc(sizeof(ScanStackEntry));
+					newEntry->ptr = nodes[nodeN]->t_tid;
+					if (out.levelAdds)
+						newEntry->level = stackEntry->level + out.levelAdds[i];
+					else
+						newEntry->level = stackEntry->level;
+					/* Must copy value out of temp context */
+					if (out.reconstructedValues)
+						newEntry->reconstructedValue =
+							datumCopy(out.reconstructedValues[i],
+									  so->state.attType.attbyval,
+									  so->state.attType.attlen);
+					else
+						newEntry->reconstructedValue = (Datum) 0;
+
+					so->scanStack = lcons(newEntry, so->scanStack);
 				}
 			}
 		}
@@ -536,10 +537,7 @@ spggetbitmap(PG_FUNCTION_ARGS)
 	TIDBitmap  *tbm = (TIDBitmap *) PG_GETARG_POINTER(1);
 	SpGistScanOpaque so = (SpGistScanOpaque) scan->opaque;
 
-	/* 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 */
+	/* Copy want_itup to *so so we don't need to pass it around separately */
 	so->want_itup = false;
 
 	so->tbm = tbm;
@@ -583,10 +581,7 @@ spggettuple(PG_FUNCTION_ARGS)
 	if (dir != ForwardScanDirection)
 		elog(ERROR, "SP-GiST only supports forward scan direction");
 
-	/* 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 */
+	/* Copy want_itup to *so so we don't need to pass it around separately */
 	so->want_itup = scan->xs_want_itup;
 
 	for (;;)