Update contrib/hstore for new GIN extractQuery API.

In particular, make hstore @> '' succeed for all hstores, likewise
hstore ?& '{}'.  Previously the results were inconsistent and could
depend on whether you were using a GiST index, GIN index, or seqscan.

contrib/hstore/expected/hstore.out

@@ -435,7 +435,7 @@ select hstore 'a=>NULL, b=>qq' ?& ARRAY['c','d'];
 select hstore 'a=>NULL, b=>qq' ?& '{}'::text[];
  ?column? 
 ----------
- f
+ t
 (1 row)
 
 -- delete

contrib/hstore/hstore_gin.c

@@ -10,6 +10,13 @@
 #include "hstore.h"
 
 
+/*
+ * When using a GIN index for hstore, we choose to index both keys and values.
+ * The storage format is "text" values, with K, V, or N prepended to the string
+ * to indicate key, value, or null values.  (As of 9.1 it might be better to
+ * store null values as nulls, but we'll keep it this way for on-disk
+ * compatibility.)
+ */
 #define KEYFLAG		'K'
 #define VALFLAG		'V'
 #define NULLFLAG	'N'
@@ -17,14 +24,17 @@
 PG_FUNCTION_INFO_V1(gin_extract_hstore);
 Datum		gin_extract_hstore(PG_FUNCTION_ARGS);
 
+/* Build an indexable text value */
 static text *
-makeitem(char *str, int len)
+makeitem(char *str, int len, char flag)
 {
 	text	   *item;
 
 	item = (text *) palloc(VARHDRSZ + len + 1);
 	SET_VARSIZE(item, VARHDRSZ + len + 1);
 
+	*VARDATA(item) = flag;
+
 	if (str && len > 0)
 		memcpy(VARDATA(item) + 1, str, len);
 
@@ -50,20 +60,15 @@ gin_extract_hstore(PG_FUNCTION_ARGS)
 	{
 		text	   *item;
 
-		item = makeitem(HS_KEY(hsent, ptr, i), HS_KEYLEN(hsent, i));
-		*VARDATA(item) = KEYFLAG;
+		item = makeitem(HS_KEY(hsent, ptr, i), HS_KEYLEN(hsent, i),
+						KEYFLAG);
 		entries[2 * i] = PointerGetDatum(item);
 
 		if (HS_VALISNULL(hsent, i))
-		{
-			item = makeitem(NULL, 0);
-			*VARDATA(item) = NULLFLAG;
-		}
+			item = makeitem(NULL, 0, NULLFLAG);
 		else
-		{
-			item = makeitem(HS_VAL(hsent, ptr, i), HS_VALLEN(hsent, i));
-			*VARDATA(item) = VALFLAG;
-		}
+			item = makeitem(HS_VAL(hsent, ptr, i), HS_VALLEN(hsent, i),
+							VALFLAG);
 		entries[2 * i + 1] = PointerGetDatum(item);
 	}
 
@@ -76,30 +81,31 @@ Datum		gin_extract_hstore_query(PG_FUNCTION_ARGS);
 Datum
 gin_extract_hstore_query(PG_FUNCTION_ARGS)
 {
+	int32	   *nentries = (int32 *) PG_GETARG_POINTER(1);
 	StrategyNumber strategy = PG_GETARG_UINT16(2);
+	int32	   *searchMode = (int32 *) PG_GETARG_POINTER(6);
+	Datum	   *entries;
 
 	if (strategy == HStoreContainsStrategyNumber)
 	{
-		PG_RETURN_DATUM(DirectFunctionCall2(gin_extract_hstore,
-											PG_GETARG_DATUM(0),
-											PG_GETARG_DATUM(1)
-											));
+		/* Query is an hstore, so just apply gin_extract_hstore... */
+		entries = (Datum *)
+			DatumGetPointer(DirectFunctionCall2(gin_extract_hstore,
+												PG_GETARG_DATUM(0),
+												PointerGetDatum(nentries)));
+		/* ... except that "contains {}" requires a full index scan */
+		if (entries == NULL)
+			*searchMode = GIN_SEARCH_MODE_ALL;
 	}
 	else if (strategy == HStoreExistsStrategyNumber)
 	{
-		text	   *item,
-				   *query = PG_GETARG_TEXT_PP(0);
-		int32	   *nentries = (int32 *) PG_GETARG_POINTER(1);
-		Datum	   *entries = NULL;
+		text	   *query = PG_GETARG_TEXT_PP(0);
+		text	   *item;
 
 		*nentries = 1;
 		entries = (Datum *) palloc(sizeof(Datum));
-
-		item = makeitem(VARDATA_ANY(query), VARSIZE_ANY_EXHDR(query));
-		*VARDATA(item) = KEYFLAG;
+		item = makeitem(VARDATA_ANY(query), VARSIZE_ANY_EXHDR(query), KEYFLAG);
 		entries[0] = PointerGetDatum(item);
-
-		PG_RETURN_POINTER(entries);
 	}
 	else if (strategy == HStoreExistsAnyStrategyNumber ||
 			 strategy == HStoreExistsAllStrategyNumber)
@@ -110,8 +116,6 @@ gin_extract_hstore_query(PG_FUNCTION_ARGS)
 		int			key_count;
 		int			i,
 					j;
-		int32	   *nentries = (int32 *) PG_GETARG_POINTER(1);
-		Datum	   *entries = NULL;
 		text	   *item;
 
 		deconstruct_array(query,
@@ -122,21 +126,25 @@ gin_extract_hstore_query(PG_FUNCTION_ARGS)
 
 		for (i = 0, j = 0; i < key_count; ++i)
 		{
+			/* Nulls in the array are ignored, cf hstoreArrayToPairs */
 			if (key_nulls[i])
 				continue;
-			item = makeitem(VARDATA(key_datums[i]), VARSIZE(key_datums[i]) - VARHDRSZ);
-			*VARDATA(item) = KEYFLAG;
+			item = makeitem(VARDATA(key_datums[i]), VARSIZE(key_datums[i]) - VARHDRSZ, KEYFLAG);
 			entries[j++] = PointerGetDatum(item);
 		}
 
-		*nentries = j ? j : -1;
-
-		PG_RETURN_POINTER(entries);
+		*nentries = j;
+		/* ExistsAll with no keys should match everything */
+		if (j == 0 && strategy == HStoreExistsAllStrategyNumber)
+			*searchMode = GIN_SEARCH_MODE_ALL;
 	}
 	else
-		elog(ERROR, "Unsupported strategy number: %d", strategy);
+	{
+		elog(ERROR, "unrecognized strategy number: %d", strategy);
+		entries = NULL;			/* keep compiler quiet */
+	}
 
-	PG_RETURN_POINTER(NULL);
+	PG_RETURN_POINTER(entries);
 }
 
 PG_FUNCTION_INFO_V1(gin_consistent_hstore);
@@ -154,42 +162,52 @@ gin_consistent_hstore(PG_FUNCTION_ARGS)
 	/* Pointer	   *extra_data = (Pointer *) PG_GETARG_POINTER(4); */
 	bool	   *recheck = (bool *) PG_GETARG_POINTER(5);
 	bool		res = true;
-
-	*recheck = false;
+	int32		i;
 
 	if (strategy == HStoreContainsStrategyNumber)
 	{
-		int			i;
-
 		/*
-		 * Index lost information about correspondence of keys and values, so
-		 * we need recheck (pre-8.4 this is handled at SQL level)
+		 * Index doesn't have information about correspondence of keys and
+		 * values, so we need recheck.  However, if not all the keys are
+		 * present, we can fail at once.
 		 */
 		*recheck = true;
-		for (i = 0; res && i < nkeys; i++)
-			if (check[i] == false)
+		for (i = 0; i < nkeys; i++)
+		{
+			if (!check[i])
+			{
 				res = false;
+				break;
+			}
+		}
 	}
 	else if (strategy == HStoreExistsStrategyNumber)
 	{
-		/* Existence of key is guaranteed */
+		/* Existence of key is guaranteed in default search mode */
+		*recheck = false;
 		res = true;
 	}
 	else if (strategy == HStoreExistsAnyStrategyNumber)
 	{
-		/* Existence of key is guaranteed */
+		/* Existence of key is guaranteed in default search mode */
+		*recheck = false;
 		res = true;
 	}
 	else if (strategy == HStoreExistsAllStrategyNumber)
 	{
-		int			i;
-
-		for (i = 0; res && i < nkeys; ++i)
+		/* Testing for all the keys being present gives an exact result */
+		*recheck = false;
+		for (i = 0; i < nkeys; i++)
+		{
 			if (!check[i])
+			{
 				res = false;
+				break;
+			}
+		}
 	}
 	else
-		elog(ERROR, "Unsupported strategy number: %d", strategy);
+		elog(ERROR, "unrecognized strategy number: %d", strategy);
 
 	PG_RETURN_BOOL(res);
 }

contrib/hstore/hstore_op.c

@@ -168,14 +168,16 @@ hstore_exists_any(PG_FUNCTION_ARGS)
 	 * start one entry past the previous "found" entry, or at the lower bound
 	 * of the last search.
 	 */
-
-	for (i = 0; !res && i < nkeys; ++i)
+	for (i = 0; i < nkeys; i++)
 	{
 		int			idx = hstoreFindKey(hs, &lowbound,
 									  key_pairs[i].key, key_pairs[i].keylen);
 
 		if (idx >= 0)
+		{
 			res = true;
+			break;
+		}
 	}
 
 	PG_RETURN_BOOL(res);
@@ -193,7 +195,7 @@ hstore_exists_all(PG_FUNCTION_ARGS)
 	Pairs	   *key_pairs = hstoreArrayToPairs(keys, &nkeys);
 	int			i;
 	int			lowbound = 0;
-	bool		res = nkeys ? true : false;
+	bool		res = true;
 
 	/*
 	 * we exploit the fact that the pairs list is already sorted into strictly
@@ -201,14 +203,16 @@ hstore_exists_all(PG_FUNCTION_ARGS)
 	 * start one entry past the previous "found" entry, or at the lower bound
 	 * of the last search.
 	 */
-
-	for (i = 0; res && i < nkeys; ++i)
+	for (i = 0; i < nkeys; i++)
 	{
 		int			idx = hstoreFindKey(hs, &lowbound,
 									  key_pairs[i].key, key_pairs[i].keylen);
 
 		if (idx < 0)
+		{
 			res = false;
+			break;
+		}
 	}
 
 	PG_RETURN_BOOL(res);