From 92a30a7eb0cadb008e18053f199af7de3fc1abaa Mon Sep 17 00:00:00 2001
From: Tom Lane
Date: Wed, 13 Apr 2016 23:33:31 -0400
Subject: Fix broken dependency-mongering for index operator classes/families.

For a long time, opclasscmds.c explained that "we do not create a
dependency link to the AM [for an opclass or opfamily], because we don't
currently support DROP ACCESS METHOD".  Commit 473b93287040b200 invented
DROP ACCESS METHOD, but it batted only 1 for 2 on adding the dependency
links, and 0 for 2 on updating the comments about the topic.

In passing, undo the same commit's entirely inappropriate decision to
blow away an existing index as a side-effect of create_am.sql.
---
 src/backend/commands/opclasscmds.c | 21 +++++++++------------
 1 file changed, 9 insertions(+), 12 deletions(-)

(limited to 'src/backend')

diff --git a/src/backend/commands/opclasscmds.c b/src/backend/commands/opclasscmds.c
index ac559fc9b41..5f665cf3a20 100644
--- a/src/backend/commands/opclasscmds.c
+++ b/src/backend/commands/opclasscmds.c
@@ -285,14 +285,18 @@ CreateOpFamily(char *amname, char *opfname, Oid namespaceoid, Oid amoid)
 	heap_freetuple(tup);
 
 	/*
-	 * Create dependencies for the opfamily proper.  Note: we do not create a
-	 * dependency link to the AM, because we don't currently support DROP
-	 * ACCESS METHOD.
+	 * Create dependencies for the opfamily proper.
 	 */
 	myself.classId = OperatorFamilyRelationId;
 	myself.objectId = opfamilyoid;
 	myself.objectSubId = 0;
 
+	/* dependency on access method */
+	referenced.classId = AccessMethodRelationId;
+	referenced.objectId = amoid;
+	referenced.objectSubId = 0;
+	recordDependencyOn(&myself, &referenced, DEPENDENCY_AUTO);
+
 	/* dependency on namespace */
 	referenced.classId = NamespaceRelationId;
 	referenced.objectId = namespaceoid;
@@ -670,20 +674,13 @@ DefineOpClass(CreateOpClassStmt *stmt)
 	EventTriggerCollectCreateOpClass(stmt, opclassoid, operators, procedures);
 
 	/*
-	 * Create dependencies for the opclass proper.  Note: we do not create a
-	 * dependency link to the AM, because we don't currently support DROP
-	 * ACCESS METHOD.
+	 * Create dependencies for the opclass proper.  Note: we do not need a
+	 * dependency link to the AM, because that exists through the opfamily.
 	 */
 	myself.classId = OperatorClassRelationId;
 	myself.objectId = opclassoid;
 	myself.objectSubId = 0;
 
-	/* dependency on access method */
-	referenced.classId = AccessMethodRelationId;
-	referenced.objectId = amoid;
-	referenced.objectSubId = 0;
-	recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
-
 	/* dependency on namespace */
 	referenced.classId = NamespaceRelationId;
 	referenced.objectId = namespaceoid;
-- 
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