Fix planner to consider matches to boolean columns in extension indexes.

The planner has to special-case indexes on boolean columns, because
what we need for an indexscan on such a column is a qual of the shape
of "boolvar = pseudoconstant".  For plain bool constants, previous
simplification will have reduced this to "boolvar" or "NOT boolvar",
and we have to reverse that if we want to make an indexqual.  There is
existing code to do so, but it only fires when the index's opfamily
is BOOL_BTREE_FAM_OID or BOOL_HASH_FAM_OID.  Thus extension AMs, or
extension opclasses such as contrib/btree_gin, are out in the cold.

The reason for hard-wiring the set of relevant opfamilies was mostly
to avoid a catalog lookup in a hot code path.  We can improve matters
while not taking much of a performance hit by relying on the
hard-wired set when the opfamily OID is visibly built-in, and only
checking the catalogs when dealing with an extension opfamily.

While here, rename IsBooleanOpfamily to IsBuiltinBooleanOpfamily
to remind future users of that macro of its limitations.  At some
point we might want to make indxpath.c's improved version of the
test globally accessible, but it's not presently needed elsewhere.

Zongliang Quan and Tom Lane

Discussion: https://postgr.es/m/f293b91d-1d46-d386-b6bb-4b06ff5c667b@yeah.net

contrib/btree_gin/expected/bool.out

@@ -87,13 +87,15 @@ EXPLAIN (COSTS OFF) SELECT * FROM test_bool WHERE i<=true ORDER BY i;
 (6 rows)
 
 EXPLAIN (COSTS OFF) SELECT * FROM test_bool WHERE i=true ORDER BY i;
-         QUERY PLAN          
+                QUERY PLAN                 
------------------------------
+-------------------------------------------
  Sort
    Sort Key: i
-   ->  Seq Scan on test_bool
+   ->  Bitmap Heap Scan on test_bool
          Filter: i
-(4 rows)
+         ->  Bitmap Index Scan on idx_bool
+               Index Cond: (i = true)
+(6 rows)
 
 EXPLAIN (COSTS OFF) SELECT * FROM test_bool WHERE i>=true ORDER BY i;
                 QUERY PLAN                 

contrib/btree_gist/expected/bool.out

@@ -71,7 +71,7 @@ SELECT * FROM booltmp WHERE a;
                 QUERY PLAN                
 ------------------------------------------
  Index Only Scan using boolidx on booltmp
-   Filter: a
+   Index Cond: (a = true)
 (2 rows)
 
 SELECT * FROM booltmp WHERE a;
@@ -85,7 +85,7 @@ SELECT * FROM booltmp WHERE NOT a;
                 QUERY PLAN                
 ------------------------------------------
  Index Only Scan using boolidx on booltmp
-   Filter: (NOT a)
+   Index Cond: (a = false)
 (2 rows)
 
 SELECT * FROM booltmp WHERE NOT a;

src/backend/optimizer/path/indxpath.c

@@ -153,6 +153,7 @@ static IndexClause *match_clause_to_indexcol(PlannerInfo *root,
 											 RestrictInfo *rinfo,
 											 int indexcol,
 											 IndexOptInfo *index);
+static bool IsBooleanOpfamily(Oid opfamily);
 static IndexClause *match_boolean_index_clause(PlannerInfo *root,
 											   RestrictInfo *rinfo,
 											   int indexcol, IndexOptInfo *index);
@@ -2342,6 +2343,23 @@ match_clause_to_indexcol(PlannerInfo *root,
 	return NULL;
 }
 
+/*
+ * IsBooleanOpfamily
+ *	  Detect whether an opfamily supports boolean equality as an operator.
+ *
+ * If the opfamily OID is in the range of built-in objects, we can rely
+ * on hard-wired knowledge of which built-in opfamilies support this.
+ * For extension opfamilies, there's no choice but to do a catcache lookup.
+ */
+static bool
+IsBooleanOpfamily(Oid opfamily)
+{
+	if (opfamily < FirstNormalObjectId)
+		return IsBuiltinBooleanOpfamily(opfamily);
+	else
+		return op_in_opfamily(BooleanEqualOperator, opfamily);
+}
+
 /*
  * match_boolean_index_clause
  *	  Recognize restriction clauses that can be matched to a boolean index.

src/backend/optimizer/path/pathkeys.c

@@ -1191,8 +1191,13 @@ partkey_is_bool_constant_for_query(RelOptInfo *partrel, int partkeycol)
 	PartitionScheme partscheme = partrel->part_scheme;
 	ListCell   *lc;
 
-	/* If the partkey isn't boolean, we can't possibly get a match */
+	/*
-	if (!IsBooleanOpfamily(partscheme->partopfamily[partkeycol]))
+	 * If the partkey isn't boolean, we can't possibly get a match.
+	 *
+	 * Partitioning currently can only use built-in AMs, so checking for
+	 * built-in boolean opfamilies is good enough.
+	 */
+	if (!IsBuiltinBooleanOpfamily(partscheme->partopfamily[partkeycol]))
 		return false;
 
 	/* Check each restriction clause for the partitioned rel */

src/backend/partitioning/partprune.c

@@ -3596,7 +3596,11 @@ match_boolean_partition_clause(Oid partopfamily, Expr *clause, Expr *partkey,
 
 	*outconst = NULL;
 
-	if (!IsBooleanOpfamily(partopfamily))
+	/*
+	 * Partitioning currently can only use built-in AMs, so checking for
+	 * built-in boolean opfamilies is good enough.
+	 */
+	if (!IsBuiltinBooleanOpfamily(partopfamily))
 		return PARTCLAUSE_UNSUPPORTED;
 
 	if (IsA(clause, BooleanTest))

src/include/catalog/pg_opfamily.h

@@ -55,7 +55,8 @@ DECLARE_UNIQUE_INDEX_PKEY(pg_opfamily_oid_index, 2755, OpfamilyOidIndexId, on pg
 
 #ifdef EXPOSE_TO_CLIENT_CODE
 
-#define IsBooleanOpfamily(opfamily) \
+/* This does not account for non-core opfamilies that might accept boolean */
+#define IsBuiltinBooleanOpfamily(opfamily) \
 	((opfamily) == BOOL_BTREE_FAM_OID || (opfamily) == BOOL_HASH_FAM_OID)
 
 #endif							/* EXPOSE_TO_CLIENT_CODE */