Generalize hash and ordering support in amapi

Stop comparing access method OID values against HASH_AM_OID and
BTREE_AM_OID, and instead check the IndexAmRoutine for an index to see
if it advertises its ability to perform the necessary ordering,
hashing, or cross-type comparing functionality.  A field amcanorder
already existed, this uses it more widely.  Fields amcanhash and
amcancrosscompare are added for the other purposes.

Author: Mark Dilger <mark.dilger@enterprisedb.com>
Discussion: https://www.postgresql.org/message-id/flat/E72EAA49-354D-4C2E-8EB9-255197F55330@enterprisedb.com

contrib/bloom/blutils.c

@@ -109,6 +109,8 @@ blhandler(PG_FUNCTION_ARGS)
 	amroutine->amoptsprocnum = BLOOM_OPTIONS_PROC;
 	amroutine->amcanorder = false;
 	amroutine->amcanorderbyop = false;
+	amroutine->amcanhash = false;
+	amroutine->amcancrosscompare = false;
 	amroutine->amcanbackward = false;
 	amroutine->amcanunique = false;
 	amroutine->amcanmulticol = true;

doc/src/sgml/indexam.sgml

@@ -103,6 +103,10 @@ typedef struct IndexAmRoutine
     bool        amcanorder;
     /* does AM support ORDER BY result of an operator on indexed column? */
     bool        amcanorderbyop;
+    /* does AM support hashing using API consistent with the hash AM? */
+    bool        amcanhash;
+    /* does AM support cross-type comparisons? */
+    bool        amcancrosscompare;
     /* does AM support backward scanning? */
     bool        amcanbackward;
     /* does AM support UNIQUE indexes? */

src/backend/access/brin/brin.c

@@ -256,6 +256,8 @@ brinhandler(PG_FUNCTION_ARGS)
 	amroutine->amoptsprocnum = BRIN_PROCNUM_OPTIONS;
 	amroutine->amcanorder = false;
 	amroutine->amcanorderbyop = false;
+	amroutine->amcanhash = false;
+	amroutine->amcancrosscompare = false;
 	amroutine->amcanbackward = false;
 	amroutine->amcanunique = false;
 	amroutine->amcanmulticol = true;

src/backend/access/gin/ginutil.c

@@ -43,6 +43,8 @@ ginhandler(PG_FUNCTION_ARGS)
 	amroutine->amoptsprocnum = GIN_OPTIONS_PROC;
 	amroutine->amcanorder = false;
 	amroutine->amcanorderbyop = false;
+	amroutine->amcanhash = false;
+	amroutine->amcancrosscompare = false;
 	amroutine->amcanbackward = false;
 	amroutine->amcanunique = false;
 	amroutine->amcanmulticol = true;

src/backend/access/gist/gist.c

@@ -65,6 +65,8 @@ gisthandler(PG_FUNCTION_ARGS)
 	amroutine->amoptsprocnum = GIST_OPTIONS_PROC;
 	amroutine->amcanorder = false;
 	amroutine->amcanorderbyop = true;
+	amroutine->amcanhash = false;
+	amroutine->amcancrosscompare = false;
 	amroutine->amcanbackward = false;
 	amroutine->amcanunique = false;
 	amroutine->amcanmulticol = true;

src/backend/access/hash/hash.c

@@ -64,6 +64,8 @@ hashhandler(PG_FUNCTION_ARGS)
 	amroutine->amoptsprocnum = HASHOPTIONS_PROC;
 	amroutine->amcanorder = false;
 	amroutine->amcanorderbyop = false;
+	amroutine->amcanhash = true;
+	amroutine->amcancrosscompare = false;
 	amroutine->amcanbackward = true;
 	amroutine->amcanunique = false;
 	amroutine->amcanmulticol = false;

src/backend/access/nbtree/nbtree.c

@@ -107,6 +107,8 @@ bthandler(PG_FUNCTION_ARGS)
 	amroutine->amoptsprocnum = BTOPTIONS_PROC;
 	amroutine->amcanorder = true;
 	amroutine->amcanorderbyop = false;
+	amroutine->amcanhash = false;
+	amroutine->amcancrosscompare = true;
 	amroutine->amcanbackward = true;
 	amroutine->amcanunique = true;
 	amroutine->amcanmulticol = true;

src/backend/access/spgist/spgutils.c

@@ -50,6 +50,8 @@ spghandler(PG_FUNCTION_ARGS)
 	amroutine->amoptsprocnum = SPGIST_OPTIONS_PROC;
 	amroutine->amcanorder = false;
 	amroutine->amcanorderbyop = true;
+	amroutine->amcanhash = false;
+	amroutine->amcancrosscompare = false;
 	amroutine->amcanbackward = false;
 	amroutine->amcanunique = false;
 	amroutine->amcanmulticol = false;

src/backend/commands/opclasscmds.c

@@ -1242,25 +1242,25 @@ assignProcTypes(OpFamilyMember *member, Oid amoid, Oid typeoid,
 	}
 
 	/*
-	 * btree comparison procs must be 2-arg procs returning int4.  btree
-	 * sortsupport procs must take internal and return void.  btree in_range
-	 * procs must be 5-arg procs returning bool.  btree equalimage procs must
-	 * take 1 arg and return bool.  hash support proc 1 must be a 1-arg proc
-	 * returning int4, while proc 2 must be a 2-arg proc returning int8.
-	 * Otherwise we don't know.
+	 * Ordering comparison procs must be 2-arg procs returning int4.  Ordering
+	 * sortsupport procs must take internal and return void.  Ordering
+	 * in_range procs must be 5-arg procs returning bool.  Ordering equalimage
+	 * procs must take 1 arg and return bool.  Hashing support proc 1 must be
+	 * a 1-arg proc returning int4, while proc 2 must be a 2-arg proc
+	 * returning int8. Otherwise we don't know.
 	 */
-	else if (amoid == BTREE_AM_OID)
+	else if (GetIndexAmRoutineByAmId(amoid, false)->amcanorder)
 	{
 		if (member->number == BTORDER_PROC)
 		{
 			if (procform->pronargs != 2)
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
-						 errmsg("btree comparison functions must have two arguments")));
+						 errmsg("ordering comparison functions must have two arguments")));
 			if (procform->prorettype != INT4OID)
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
-						 errmsg("btree comparison functions must return integer")));
+						 errmsg("ordering comparison functions must return integer")));
 
 			/*
 			 * If lefttype/righttype isn't specified, use the proc's input
@@ -1277,11 +1277,11 @@ assignProcTypes(OpFamilyMember *member, Oid amoid, Oid typeoid,
 				procform->proargtypes.values[0] != INTERNALOID)
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
-						 errmsg("btree sort support functions must accept type \"internal\"")));
+						 errmsg("ordering sort support functions must accept type \"internal\"")));
 			if (procform->prorettype != VOIDOID)
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
-						 errmsg("btree sort support functions must return void")));
+						 errmsg("ordering sort support functions must return void")));
 
 			/*
 			 * Can't infer lefttype/righttype from proc, so use default rule
@@ -1292,11 +1292,11 @@ assignProcTypes(OpFamilyMember *member, Oid amoid, Oid typeoid,
 			if (procform->pronargs != 5)
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
-						 errmsg("btree in_range functions must have five arguments")));
+						 errmsg("ordering in_range functions must have five arguments")));
 			if (procform->prorettype != BOOLOID)
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
-						 errmsg("btree in_range functions must return boolean")));
+						 errmsg("ordering in_range functions must return boolean")));
 
 			/*
 			 * If lefttype/righttype isn't specified, use the proc's input
@@ -1312,11 +1312,11 @@ assignProcTypes(OpFamilyMember *member, Oid amoid, Oid typeoid,
 			if (procform->pronargs != 1)
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
-						 errmsg("btree equal image functions must have one argument")));
+						 errmsg("ordering equal image functions must have one argument")));
 			if (procform->prorettype != BOOLOID)
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
-						 errmsg("btree equal image functions must return boolean")));
+						 errmsg("ordering equal image functions must return boolean")));
 
 			/*
 			 * pg_amproc functions are indexed by (lefttype, righttype), but
@@ -1329,10 +1329,10 @@ assignProcTypes(OpFamilyMember *member, Oid amoid, Oid typeoid,
 			if (member->lefttype != member->righttype)
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
-						 errmsg("btree equal image functions must not be cross-type")));
+						 errmsg("ordering equal image functions must not be cross-type")));
 		}
 	}
-	else if (amoid == HASH_AM_OID)
+	else if (GetIndexAmRoutineByAmId(amoid, false)->amcanhash)
 	{
 		if (member->number == HASHSTANDARD_PROC)
 		{

src/backend/executor/nodeIndexscan.c

@@ -1331,10 +1331,10 @@ ExecIndexBuildScanKeys(PlanState *planstate, Relation index,
 				varattno = ((Var *) leftop)->varattno;
 
 				/*
-				 * We have to look up the operator's associated btree support
+				 * We have to look up the operator's associated support
 				 * function
 				 */
-				if (index->rd_rel->relam != BTREE_AM_OID ||
+				if (!index->rd_indam->amcanorder ||
 					varattno < 1 || varattno > indnkeyatts)
 					elog(ERROR, "bogus RowCompare index qualification");
 				opfamily = index->rd_opfamily[varattno - 1];

src/backend/utils/cache/lsyscache.c

@@ -716,10 +716,9 @@ equality_ops_are_compatible(Oid opno1, Oid opno2)
 	{
 		HeapTuple	op_tuple = &catlist->members[i]->tuple;
 		Form_pg_amop op_form = (Form_pg_amop) GETSTRUCT(op_tuple);
+		IndexAmRoutine *amroutine = GetIndexAmRoutineByAmId(op_form->amopmethod, false);
 
-		/* must be btree or hash */
-		if (op_form->amopmethod == BTREE_AM_OID ||
-			op_form->amopmethod == HASH_AM_OID)
+		if (amroutine->amcancrosscompare)
 		{
 			if (op_in_opfamily(opno2, op_form->amopfamily))
 			{
@@ -767,8 +766,9 @@ comparison_ops_are_compatible(Oid opno1, Oid opno2)
 	{
 		HeapTuple	op_tuple = &catlist->members[i]->tuple;
 		Form_pg_amop op_form = (Form_pg_amop) GETSTRUCT(op_tuple);
+		IndexAmRoutine *amroutine = GetIndexAmRoutineByAmId(op_form->amopmethod, false);
 
-		if (op_form->amopmethod == BTREE_AM_OID)
+		if (amroutine->amcanorder && amroutine->amcancrosscompare)
 		{
 			if (op_in_opfamily(opno2, op_form->amopfamily))
 			{

src/include/access/amapi.h

@@ -243,6 +243,10 @@ typedef struct IndexAmRoutine
 	bool		amcanorder;
 	/* does AM support ORDER BY result of an operator on indexed column? */
 	bool		amcanorderbyop;
+	/* does AM support hashing using API consistent with the hash AM? */
+	bool		amcanhash;
+	/* does AM support cross-type comparisons? */
+	bool		amcancrosscompare;
 	/* does AM support backward scanning? */
 	bool		amcanbackward;
 	/* does AM support UNIQUE indexes? */

src/test/modules/dummy_index_am/dummy_index_am.c

@@ -282,6 +282,8 @@ dihandler(PG_FUNCTION_ARGS)
 	amroutine->amsupport = 1;
 	amroutine->amcanorder = false;
 	amroutine->amcanorderbyop = false;
+	amroutine->amcanhash = false;
+	amroutine->amcancrosscompare = false;
 	amroutine->amcanbackward = false;
 	amroutine->amcanunique = false;
 	amroutine->amcanmulticol = false;

src/test/regress/expected/alter_generic.out

@@ -420,7 +420,7 @@ BEGIN TRANSACTION;
 CREATE OPERATOR FAMILY alt_opf12 USING btree;
 CREATE FUNCTION fn_opf12  (int4, int2) RETURNS BIGINT AS 'SELECT NULL::BIGINT;' LANGUAGE SQL;
 ALTER OPERATOR FAMILY alt_opf12 USING btree ADD FUNCTION 1 fn_opf12(int4, int2);
-ERROR:  btree comparison functions must return integer
+ERROR:  ordering comparison functions must return integer
 DROP OPERATOR FAMILY alt_opf12 USING btree;
 ERROR:  current transaction is aborted, commands ignored until end of transaction block
 ROLLBACK;
@@ -438,7 +438,7 @@ BEGIN TRANSACTION;
 CREATE OPERATOR FAMILY alt_opf14 USING btree;
 CREATE FUNCTION fn_opf14 (int4) RETURNS BIGINT AS 'SELECT NULL::BIGINT;' LANGUAGE SQL;
 ALTER OPERATOR FAMILY alt_opf14 USING btree ADD FUNCTION 1 fn_opf14(int4);
-ERROR:  btree comparison functions must have two arguments
+ERROR:  ordering comparison functions must have two arguments
 DROP OPERATOR FAMILY alt_opf14 USING btree;
 ERROR:  current transaction is aborted, commands ignored until end of transaction block
 ROLLBACK;
@@ -504,7 +504,7 @@ ALTER OPERATOR FAMILY alt_opf18 USING btree ADD
 -- Should fail. Not allowed to have cross-type equalimage function.
 ALTER OPERATOR FAMILY alt_opf18 USING btree
   ADD FUNCTION 4 (int4, int2) btequalimage(oid);
-ERROR:  btree equal image functions must not be cross-type
+ERROR:  ordering equal image functions must not be cross-type
 ALTER OPERATOR FAMILY alt_opf18 USING btree DROP FUNCTION 2 (int4, int4);
 ERROR:  function 2(integer,integer) does not exist in operator family "alt_opf18"
 DROP OPERATOR FAMILY alt_opf18 USING btree;