Reduce lock level for altering fillfactor

Fabrízio de Royes Mello and Simon Riggs

Author: simonat2ndQuadrant

doc/src/sgml/ref/alter_table.sgml

@@ -561,7 +561,7 @@ ALTER TABLE ALL IN TABLESPACE <replaceable class="PARAMETER">name</replaceable>
      </para>
 
      <para>
-      Changing autovacuum storage parameters acquires a <literal>SHARE UPDATE EXCLUSIVE</literal> lock.
+      Changing fillfactor and autovacuum storage parameters acquires a <literal>SHARE UPDATE EXCLUSIVE</literal> lock.
      </para>
 
      <note>

src/backend/access/common/reloptions.c

@@ -100,7 +100,7 @@ static relopt_int intRelOpts[] =
 			"fillfactor",
 			"Packs table pages only to this percentage",
 			RELOPT_KIND_HEAP,
-			AccessExclusiveLock
+			ShareUpdateExclusiveLock /* since it applies only to later inserts */
 		},
 		HEAP_DEFAULT_FILLFACTOR, HEAP_MIN_FILLFACTOR, 100
 	},
@@ -109,7 +109,7 @@ static relopt_int intRelOpts[] =
 			"fillfactor",
 			"Packs btree index pages only to this percentage",
 			RELOPT_KIND_BTREE,
-			AccessExclusiveLock
+			ShareUpdateExclusiveLock /* since it applies only to later inserts */
 		},
 		BTREE_DEFAULT_FILLFACTOR, BTREE_MIN_FILLFACTOR, 100
 	},
@@ -118,7 +118,7 @@ static relopt_int intRelOpts[] =
 			"fillfactor",
 			"Packs hash index pages only to this percentage",
 			RELOPT_KIND_HASH,
-			AccessExclusiveLock
+			ShareUpdateExclusiveLock /* since it applies only to later inserts */
 		},
 		HASH_DEFAULT_FILLFACTOR, HASH_MIN_FILLFACTOR, 100
 	},
@@ -127,7 +127,7 @@ static relopt_int intRelOpts[] =
 			"fillfactor",
 			"Packs gist index pages only to this percentage",
 			RELOPT_KIND_GIST,
-			AccessExclusiveLock
+			ShareUpdateExclusiveLock /* since it applies only to later inserts */
 		},
 		GIST_DEFAULT_FILLFACTOR, GIST_MIN_FILLFACTOR, 100
 	},
@@ -136,7 +136,7 @@ static relopt_int intRelOpts[] =
 			"fillfactor",
 			"Packs spgist index pages only to this percentage",
 			RELOPT_KIND_SPGIST,
-			AccessExclusiveLock
+			ShareUpdateExclusiveLock /* since it applies only to later inserts */
 		},
 		SPGIST_DEFAULT_FILLFACTOR, SPGIST_MIN_FILLFACTOR, 100
 	},

src/test/regress/expected/alter_table.out

@@ -2065,19 +2065,19 @@ select * from my_locks order by 1;
 commit;
 begin; alter table alterlock set (fillfactor = 100);
 select * from my_locks order by 1;
-  relname  |    max_lockmode     
------------+---------------------
- alterlock | AccessExclusiveLock
- pg_toast  | AccessExclusiveLock
+  relname  |       max_lockmode       
+-----------+--------------------------
+ alterlock | ShareUpdateExclusiveLock
+ pg_toast  | ShareUpdateExclusiveLock
 (2 rows)
 
 commit;
 begin; alter table alterlock reset (fillfactor);
 select * from my_locks order by 1;
-  relname  |    max_lockmode     
------------+---------------------
- alterlock | AccessExclusiveLock
- pg_toast  | AccessExclusiveLock
+  relname  |       max_lockmode       
+-----------+--------------------------
+ alterlock | ShareUpdateExclusiveLock
+ pg_toast  | ShareUpdateExclusiveLock
 (2 rows)
 
 commit;
@@ -2110,10 +2110,10 @@ rollback;
 -- test that mixing options with different lock levels works as expected
 begin; alter table alterlock set (autovacuum_enabled = off, fillfactor = 80);
 select * from my_locks order by 1;
-  relname  |    max_lockmode     
------------+---------------------
- alterlock | AccessExclusiveLock
- pg_toast  | AccessExclusiveLock
+  relname  |       max_lockmode       
+-----------+--------------------------
+ alterlock | ShareUpdateExclusiveLock
+ pg_toast  | ShareUpdateExclusiveLock
 (2 rows)
 
 commit;