Speed up dropping tables with many partitions.

We need to lock the parent, but we don't need a relcache entry
for it.

Gao Zeng Qi, reviewed by Amit Langote

Discussion: http://postgr.es/m/CAFmBtr0ukqJjRJEhPWL5wt4rNMrJUUxggVAGXPR3SyYh3E+HDQ@mail.gmail.com

diff --git a/src/backend/catalog/heap.c b/src/backend/catalog/heap.c
index ece4df02cde98ba626838d9e22461d135c1ef929..ab3d83f29bba7a81a8e77dfbb6a9a2f9e5904274 100644 (file)
--- a/src/backend/catalog/heap.c
+++ b/src/backend/catalog/heap.c
@@ -68,6 +68,7 @@
 #include "parser/parse_collate.h"
 #include "parser/parse_expr.h"
 #include "parser/parse_relation.h"
+#include "storage/lmgr.h"
 #include "storage/predicate.h"
 #include "storage/smgr.h"
 #include "utils/acl.h"
@@ -1760,8 +1761,7 @@ heap_drop_with_catalog(Oid relid)
 {
        Relation        rel;
        HeapTuple       tuple;
-       Oid                     parentOid;
-       Relation        parent = NULL;
+       Oid                     parentOid = InvalidOid;
 
        /*
         * To drop a partition safely, we must grab exclusive lock on its parent,
@@ -1776,7 +1776,7 @@ heap_drop_with_catalog(Oid relid)
        if (((Form_pg_class) GETSTRUCT(tuple))->relispartition)
        {
                parentOid = get_partition_parent(relid);
-               parent = heap_open(parentOid, AccessExclusiveLock);
+               LockRelationOid(parentOid, AccessExclusiveLock);
        }
 
        ReleaseSysCache(tuple);
@@ -1885,14 +1885,14 @@ heap_drop_with_catalog(Oid relid)
         */
        DeleteRelationTuple(relid);
 
-       if (parent)
+       if (OidIsValid(parentOid))
        {
                /*
                 * Invalidate the parent's relcache so that the partition is no longer
                 * included in its partition descriptor.
                 */
-               CacheInvalidateRelcache(parent);
-               heap_close(parent, NoLock);             /* keep the lock */
+               CacheInvalidateRelcacheByRelid(parentOid);
+               /* keep the lock */
        }
 }