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

9 files changed, 35 insertions, 23 deletions

diff --git a/src/backend/access/brin/brin.c b/src/backend/access/brin/brin.c
index 60320440fc5..75a65ec9c75 100644
--- a/src/backend/access/brin/brin.c
+++ b/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;
diff --git a/src/backend/access/gin/ginutil.c b/src/backend/access/gin/ginutil.c
index 1f9e58c4f1f..5b643619754 100644
--- a/src/backend/access/gin/ginutil.c
+++ b/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;
diff --git a/src/backend/access/gist/gist.c b/src/backend/access/gist/gist.c
index 4d858b65e1e..5482925a0f3 100644
--- a/src/backend/access/gist/gist.c
+++ b/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;
diff --git a/src/backend/access/hash/hash.c b/src/backend/access/hash/hash.c
index b24aae415ea..a22845d7068 100644
--- a/src/backend/access/hash/hash.c
+++ b/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;
diff --git a/src/backend/access/nbtree/nbtree.c b/src/backend/access/nbtree/nbtree.c
index 411d5ac0b5f..45ea6afba1d 100644
--- a/src/backend/access/nbtree/nbtree.c
+++ b/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;
diff --git a/src/backend/access/spgist/spgutils.c b/src/backend/access/spgist/spgutils.c
index 367c36ef9af..7e56b1e6b95 100644
--- a/src/backend/access/spgist/spgutils.c
+++ b/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;
diff --git a/src/backend/commands/opclasscmds.c b/src/backend/commands/opclasscmds.c
index 2c325badf94..8546366ee06 100644
--- a/src/backend/commands/opclasscmds.c
+++ b/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)
 		{
diff --git a/src/backend/executor/nodeIndexscan.c b/src/backend/executor/nodeIndexscan.c
index 3b2275e8fe9..c30b9c2c197 100644
--- a/src/backend/executor/nodeIndexscan.c
+++ b/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];
diff --git a/src/backend/utils/cache/lsyscache.c b/src/backend/utils/cache/lsyscache.c
index bcfa5cb4add..7bd476f3de7 100644
--- a/src/backend/utils/cache/lsyscache.c
+++ b/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))
 			{