Track dependencies on shared objects (which is to say, roles; we already

have adequate mechanisms for tracking the contents of databases and
tablespaces).  This solves the longstanding problem that you can drop a
user who still owns objects and/or has access permissions.
Alvaro Herrera, with some kibitzing from Tom Lane.

src/backend/commands/conversioncmds.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/conversioncmds.c,v 1.19 2005/06/28 05:08:53 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/conversioncmds.c,v 1.20 2005/07/07 20:39:58 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -17,6 +17,7 @@
 #include "catalog/pg_conversion.h"
 #include "access/heapam.h"
 #include "catalog/catalog.h"
+#include "catalog/dependency.h"
 #include "catalog/indexing.h"
 #include "catalog/namespace.h"
 #include "catalog/pg_type.h"
@@ -220,6 +221,10 @@ AlterConversionOwner(List *name, Oid newOwnerId)
 		simple_heap_update(rel, &tup->t_self, tup);
 
 		CatalogUpdateIndexes(rel, tup);
+
+		/* Update owner dependency reference */
+		changeDependencyOnOwner(ConversionRelationId, conversionOid,
+								newOwnerId);
 	}
 
 	heap_close(rel, NoLock);

src/backend/commands/dbcommands.c

@@ -15,7 +15,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/dbcommands.c,v 1.164 2005/06/30 00:00:50 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/dbcommands.c,v 1.165 2005/07/07 20:39:58 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -28,6 +28,7 @@
 #include "access/genam.h"
 #include "access/heapam.h"
 #include "catalog/catalog.h"
+#include "catalog/dependency.h"
 #include "catalog/indexing.h"
 #include "catalog/pg_authid.h"
 #include "catalog/pg_database.h"
@@ -511,6 +512,12 @@ createdb(const CreatedbStmt *stmt)
 	/* Update indexes */
 	CatalogUpdateIndexes(pg_database_rel, tuple);
 
+	/* Register owner dependency */
+	recordDependencyOnOwner(DatabaseRelationId, dboid, datdba);
+
+	/* Create pg_shdepend entries for objects within database */
+	copyTemplateDependencies(src_dboid, dboid);
+
 	/* Close pg_database, but keep exclusive lock till commit */
 	heap_close(pg_database_rel, NoLock);
 
@@ -679,6 +686,11 @@ dropdb(const char *dbname)
 	/* Close pg_database, but keep exclusive lock till commit */
 	heap_close(pgdbrel, NoLock);
 
+	/*
+	 * Remove shared dependency references for the database.
+	 */
+	dropDatabaseDependencies(db_id);
+
 	/*
 	 * Set flag to update flat database file at commit.
 	 */
@@ -951,6 +963,10 @@ AlterDatabaseOwner(const char *dbname, Oid newOwnerId)
 		CatalogUpdateIndexes(rel, newtuple);
 
 		heap_freetuple(newtuple);
+
+		/* Update owner dependency reference */
+		changeDependencyOnOwner(DatabaseRelationId, HeapTupleGetOid(tuple),
+								newOwnerId);
 	}
 
 	systable_endscan(scan);

src/backend/commands/functioncmds.c

@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/functioncmds.c,v 1.62 2005/06/28 05:08:53 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/functioncmds.c,v 1.63 2005/07/07 20:39:58 tgl Exp $
  *
  * DESCRIPTION
  *	  These routines take the parse tree and pick out the
@@ -925,6 +925,9 @@ AlterFunctionOwner(List *name, List *argtypes, Oid newOwnerId)
 		CatalogUpdateIndexes(rel, newtuple);
 
 		heap_freetuple(newtuple);
+
+		/* Update owner dependency reference */
+		changeDependencyOnOwner(ProcedureRelationId, procOid, newOwnerId);
 	}
 
 	ReleaseSysCache(tup);

src/backend/commands/opclasscmds.c

@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/opclasscmds.c,v 1.33 2005/06/28 05:08:53 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/opclasscmds.c,v 1.34 2005/07/07 20:39:58 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -392,6 +392,9 @@ DefineOpClass(CreateOpClassStmt *stmt)
 		recordDependencyOn(&myself, &referenced, DEPENDENCY_NORMAL);
 	}
 
+	/* dependency on owner */
+	recordDependencyOnOwner(OperatorClassRelationId, opclassoid, GetUserId());
+
 	heap_close(rel, RowExclusiveLock);
 }
 
@@ -962,6 +965,9 @@ AlterOpClassOwner(List *name, const char *access_method, Oid newOwnerId)
 		simple_heap_update(rel, &tup->t_self, tup);
 
 		CatalogUpdateIndexes(rel, tup);
+
+		/* Update owner dependency reference */
+		changeDependencyOnOwner(OperatorClassRelationId, amOid, newOwnerId);
 	}
 
 	heap_close(rel, NoLock);

src/backend/commands/operatorcmds.c

@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/operatorcmds.c,v 1.22 2005/06/28 05:08:54 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/operatorcmds.c,v 1.23 2005/07/07 20:39:58 tgl Exp $
  *
  * DESCRIPTION
  *	  The "DefineFoo" routines take the parse tree and pick out the
@@ -310,6 +310,9 @@ AlterOperatorOwner(List *name, TypeName *typeName1, TypeName *typeName2,
 		simple_heap_update(rel, &tup->t_self, tup);
 
 		CatalogUpdateIndexes(rel, tup);
+
+		/* Update owner dependency reference */
+		changeDependencyOnOwner(OperatorRelationId, operOid, newOwnerId);
 	}
 
 	heap_close(rel, NoLock);

src/backend/commands/schemacmds.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/schemacmds.c,v 1.31 2005/06/28 05:08:54 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/schemacmds.c,v 1.32 2005/07/07 20:39:58 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -342,6 +342,10 @@ AlterSchemaOwner(const char *name, Oid newOwnerId)
 		CatalogUpdateIndexes(rel, newtuple);
 
 		heap_freetuple(newtuple);
+
+		/* Update owner dependency reference */
+		changeDependencyOnOwner(NamespaceRelationId, HeapTupleGetOid(tup),
+								newOwnerId);
 	}
 
 	ReleaseSysCache(tup);

src/backend/commands/tablecmds.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.162 2005/06/28 05:08:54 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.163 2005/07/07 20:39:58 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -5321,6 +5321,9 @@ ATExecChangeOwner(Oid relationOid, Oid newOwnerId)
 
 		heap_freetuple(newtuple);
 
+		/* Update owner dependency reference */
+		changeDependencyOnOwner(RelationRelationId, relationOid, newOwnerId);
+
 		/*
 		 * If we are operating on a table, also change the ownership of
 		 * any indexes and sequences that belong to the table, as well as

src/backend/commands/tablespace.c

@@ -37,7 +37,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/tablespace.c,v 1.24 2005/07/04 04:51:46 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/tablespace.c,v 1.25 2005/07/07 20:39:58 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -50,6 +50,7 @@
 
 #include "access/heapam.h"
 #include "catalog/catalog.h"
+#include "catalog/dependency.h"
 #include "catalog/indexing.h"
 #include "catalog/pg_namespace.h"
 #include "catalog/pg_tablespace.h"
@@ -307,6 +308,9 @@ CreateTableSpace(CreateTableSpaceStmt *stmt)
 
 	heap_freetuple(tuple);
 
+	/* Record dependency on owner */
+	recordDependencyOnOwner(TableSpaceRelationId, tablespaceoid, ownerId);
+
 	/*
 	 * Attempt to coerce target directory to safe permissions.	If this
 	 * fails, it doesn't exist or has the wrong owner.
@@ -818,6 +822,10 @@ AlterTableSpaceOwner(const char *name, Oid newOwnerId)
 		CatalogUpdateIndexes(rel, newtuple);
 
 		heap_freetuple(newtuple);
+
+		/* Update owner dependency reference */
+		changeDependencyOnOwner(TableSpaceRelationId, HeapTupleGetOid(tup),
+								newOwnerId);
 	}
 
 	heap_endscan(scandesc);

src/backend/commands/typecmds.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/typecmds.c,v 1.73 2005/06/28 05:08:54 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/typecmds.c,v 1.74 2005/07/07 20:39:58 tgl Exp $
  *
  * DESCRIPTION
  *	  The "DefineFoo" routines take the parse tree and pick out the
@@ -1208,6 +1208,7 @@ AlterDomainDefault(List *names, Node *defaultRaw)
 							 domainoid,
 							 typTup->typrelid,
 							 0, /* relation kind is n/a */
+							 typTup->typowner,
 							 typTup->typinput,
 							 typTup->typoutput,
 							 typTup->typreceive,
@@ -2080,6 +2081,9 @@ AlterTypeOwner(List *names, Oid newOwnerId)
 		simple_heap_update(rel, &tup->t_self, tup);
 
 		CatalogUpdateIndexes(rel, tup);
+
+		/* Update owner dependency reference */
+		changeDependencyOnOwner(TypeRelationId, typeOid, newOwnerId);
 	}
 
 	/* Clean up */

src/backend/commands/user.c

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/backend/commands/user.c,v 1.155 2005/06/29 20:34:13 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/commands/user.c,v 1.156 2005/07/07 20:39:58 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -14,10 +14,10 @@
 
 #include "access/genam.h"
 #include "access/heapam.h"
+#include "catalog/dependency.h"
 #include "catalog/indexing.h"
 #include "catalog/pg_auth_members.h"
 #include "catalog/pg_authid.h"
-#include "catalog/pg_database.h"
 #include "commands/user.h"
 #include "libpq/crypt.h"
 #include "miscadmin.h"
@@ -742,10 +742,8 @@ DropRole(DropRoleStmt *stmt)
 		const char *role = strVal(lfirst(item));
 		HeapTuple	tuple,
 					tmp_tuple;
-		Relation	pg_rel;
-		TupleDesc	pg_dsc;
-		ScanKeyData scankey;
-		HeapScanDesc scan;
+		ScanKeyData	scankey;
+		char	   *detail;
 		SysScanDesc sscan;
 		Oid			roleid;
 
@@ -780,42 +778,18 @@ DropRole(DropRoleStmt *stmt)
 					 errmsg("must be superuser to drop superusers")));
 
 		/*
-		 * Check if role still owns a database. If so, error out.
-		 *
-		 * (It used to be that this function would drop the database
-		 * automatically. This is not only very dangerous for people that
-		 * don't read the manual, it doesn't seem to be the behaviour one
-		 * would expect either.) -- petere 2000/01/14)
-		 */
-		pg_rel = heap_open(DatabaseRelationId, AccessShareLock);
-		pg_dsc = RelationGetDescr(pg_rel);
+		 * Lock the role, so nobody can add dependencies to her while we drop
+		 * her.  We keep the lock until the end of transaction.
+ 		 */
+		LockSharedObject(AuthIdRelationId, roleid, 0, AccessExclusiveLock);
 
-		ScanKeyInit(&scankey,
-					Anum_pg_database_datdba,
-					BTEqualStrategyNumber, F_OIDEQ,
-					roleid);
-
-		scan = heap_beginscan(pg_rel, SnapshotNow, 1, &scankey);
-
-		if ((tmp_tuple = heap_getnext(scan, ForwardScanDirection)) != NULL)
-		{
-			char	   *dbname;
-
-			dbname = NameStr(((Form_pg_database) GETSTRUCT(tmp_tuple))->datname);
+		/* Check for pg_shdepend entries depending on this role */
+		if ((detail = checkSharedDependencies(AuthIdRelationId, roleid)) != NULL)
 			ereport(ERROR,
-					(errcode(ERRCODE_OBJECT_IN_USE),
-					 errmsg("role \"%s\" cannot be dropped", role),
-				   errdetail("The role owns database \"%s\".", dbname)));
-		}
-
-		heap_endscan(scan);
-		heap_close(pg_rel, AccessShareLock);
-
-		/*
-		 * Somehow we'd have to check for tables, views, etc. owned by the
-		 * role as well, but those could be spread out over all sorts of
-		 * databases which we don't have access to (easily).
-		 */
+					(errcode(ERRCODE_DEPENDENT_OBJECTS_STILL_EXIST),
+					 errmsg("role \"%s\" cannot be dropped because some objects depend on it",
+						 	role),
+					 errdetail("%s", detail)));
 
 		/*
 		 * Remove the role from the pg_authid table