Have TRUNCATE advance the affected table's relfrozenxid to RecentXmin, to

avoid a later needless VACUUM for Xid-wraparound purposes.  We can do this
since the table is known to be left empty, so no Xid remains on it.

Per discussion.

diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 377bc9f4f2cbac495551efd19392aa6c40aad4f5..bd3ae31b076c4fc8c512fdf495fade6fc42ebcef 100644 (file)
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/catalog/index.c,v 1.282 2007/03/29 00:15:37 tgl Exp $
+ *   $PostgreSQL: pgsql/src/backend/catalog/index.c,v 1.283 2007/05/16 17:28:20 alvherre Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -1188,9 +1188,12 @@ index_update_stats(Relation rel, bool hasindex, bool isprimary,
  * setNewRelfilenode       - assign a new relfilenode value to the relation
  *
  * Caller must already hold exclusive lock on the relation.
+ *
+ * The relation is marked with relfrozenxid=freezeXid (InvalidTransactionId
+ * must be passed for indexes)
  */
 void
-setNewRelfilenode(Relation relation)
+setNewRelfilenode(Relation relation, TransactionId freezeXid)
 {
    Oid         newrelfilenode;
    RelFileNode newrnode;
@@ -1204,6 +1207,10 @@ setNewRelfilenode(Relation relation)
           relation->rd_rel->relkind == RELKIND_INDEX);
    /* Can't change for shared tables or indexes */
    Assert(!relation->rd_rel->relisshared);
+   /* Indexes must have Invalid frozenxid; other relations must not */
+   Assert((relation->rd_rel->relkind == RELKIND_INDEX &&
+           freezeXid == InvalidTransactionId) ||
+          TransactionIdIsNormal(freezeXid));
 
    /* Allocate a new relfilenode */
    newrelfilenode = GetNewRelFileNode(relation->rd_rel->reltablespace,
@@ -1241,6 +1248,7 @@ setNewRelfilenode(Relation relation)
    rd_rel->relfilenode = newrelfilenode;
    rd_rel->relpages = 0;       /* it's empty until further notice */
    rd_rel->reltuples = 0;
+   rd_rel->relfrozenxid = freezeXid;
    simple_heap_update(pg_class, &tuple->t_self, tuple);
    CatalogUpdateIndexes(pg_class, tuple);
 
@@ -1957,7 +1965,7 @@ reindex_index(Oid indexId)
            /*
             * We'll build a new physical relation for the index.
             */
-           setNewRelfilenode(iRel);
+           setNewRelfilenode(iRel, InvalidTransactionId);
        }
 
        /* Initialize the index and rebuild */

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index d7ad90d0217fc631561d0069c86c506c14eb3a5d..cdfbc6f0829bd94116d90390fe8705281c80d02e 100644 (file)
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.223 2007/05/14 20:24:41 tgl Exp $
+ *   $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.224 2007/05/16 17:28:20 alvherre Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -616,7 +616,7 @@ ExecuteTruncate(TruncateStmt *stmt)
         * the relfilenode value.   The old storage file is scheduled for
         * deletion at commit.
         */
-       setNewRelfilenode(rel);
+       setNewRelfilenode(rel, RecentXmin);
 
        heap_relid = RelationGetRelid(rel);
        toast_relid = rel->rd_rel->reltoastrelid;
@@ -629,7 +629,7 @@ ExecuteTruncate(TruncateStmt *stmt)
        if (OidIsValid(toast_relid))
        {
            rel = relation_open(toast_relid, AccessExclusiveLock);
-           setNewRelfilenode(rel);
+           setNewRelfilenode(rel, RecentXmin);
            heap_close(rel, NoLock);
        }
 

diff --git a/src/include/catalog/index.h b/src/include/catalog/index.h
index 32c704b71e6e421d3b923f62459273c9c670177f..7240ad600c34c721ab4535d31cd85be45e798d7c 100644 (file)
--- a/src/include/catalog/index.h
+++ b/src/include/catalog/index.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/catalog/index.h,v 1.73 2007/01/09 02:14:15 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/catalog/index.h,v 1.74 2007/05/16 17:28:20 alvherre Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -53,7 +53,7 @@ extern void FormIndexDatum(IndexInfo *indexInfo,
               Datum *values,
               bool *isnull);
 
-extern void setNewRelfilenode(Relation relation);
+extern void setNewRelfilenode(Relation relation, TransactionId freezeXid);
 
 extern void index_build(Relation heapRelation,
            Relation indexRelation,