diff -u src/backend/postmaster/autovacuum.c src/backend/postmaster/autovacuum.c
--- src/backend/postmaster/autovacuum.c	23 Jan 2009 15:56:56 -0000
+++ src/backend/postmaster/autovacuum.c	23 Jan 2009 16:49:37 -0000
@@ -1900,7 +1900,7 @@
 	/* create hash table for toast <-> main relid mapping */
 	MemSet(&ctl, 0, sizeof(ctl));
 	ctl.keysize = sizeof(Oid);
-	ctl.entrysize = sizeof(Oid) * 2;
+	ctl.entrysize = sizeof(av_relation);
 	ctl.hash = oid_hash;
 
 	table_toast_map = hash_create("TOAST to main relid map",