Revert "Prevent incorrect updates of pg_index while reindexing pg_index itself."

This reverts commit 2c69fc0596e0b785dcc990d2942be89f01c213fd of 2011-04-15.
There's a better way to do it, which will follow shortly.

diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 41309bc2c4cc84385bb383a1c65f837c8a613ba2..0f33de7b60debcc1e111d0b4d7bb1c09b3149ead 100644 (file)
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -1394,13 +1394,6 @@ index_build(Relation heapRelation,
        HeapTuple   indexTuple;
        Form_pg_index indexForm;
 
-       /*
-        * Broken HOT chains should not get reported in system catalogs; in
-        * particular it would be quite dangerous to try to modify the index's
-        * pg_index entry if we are reindexing pg_index itself.
-        */
-       Assert(!IsSystemRelation(heapRelation));
-
        pg_index = heap_open(IndexRelationId, RowExclusiveLock);
 
        indexTuple = SearchSysCacheCopy(INDEXRELID,
@@ -1460,13 +1453,7 @@ index_build(Relation heapRelation,
  * A side effect is to set indexInfo->ii_BrokenHotChain to true if we detect
  * any potentially broken HOT chains.  Currently, we set this if there are
  * any RECENTLY_DEAD entries in a HOT chain, without trying very hard to
- * detect whether they're really incompatible with the chain tip.  However,
- * we do not ever set ii_BrokenHotChain true when the relation is a system
- * catalog.  This is to avoid problematic behavior when reindexing pg_index
- * itself: we can't safely change the index's indcheckxmin field when we're
- * partway through such an operation.  It should be okay since the set of
- * indexes on a system catalog ought not change during concurrent operations,
- * so that no HOT chain in it could ever become broken.
+ * detect whether they're really incompatible with the chain tip.
  */
 double
 IndexBuildHeapScan(Relation heapRelation,
@@ -1476,7 +1463,6 @@ IndexBuildHeapScan(Relation heapRelation,
                   IndexBuildCallback callback,
                   void *callback_state)
 {
-   bool        is_system_catalog;
    HeapScanDesc scan;
    HeapTuple   heapTuple;
    Datum       values[INDEX_MAX_KEYS];
@@ -1496,9 +1482,6 @@ IndexBuildHeapScan(Relation heapRelation,
     */
    Assert(OidIsValid(indexRelation->rd_rel->relam));
 
-   /* Remember if it's a system catalog */
-   is_system_catalog = IsSystemRelation(heapRelation);
-
    /*
     * Need an EState for evaluation of index expressions and partial-index
     * predicates.  Also a slot to hold the current tuple.
@@ -1637,8 +1620,7 @@ IndexBuildHeapScan(Relation heapRelation,
                    {
                        indexIt = false;
                        /* mark the index as unsafe for old snapshots */
-                       if (!is_system_catalog)
-                           indexInfo->ii_BrokenHotChain = true;
+                       indexInfo->ii_BrokenHotChain = true;
                    }
                    else if (indexInfo->ii_BrokenHotChain)
                        indexIt = false;
@@ -1727,8 +1709,7 @@ IndexBuildHeapScan(Relation heapRelation,
                    {
                        indexIt = false;
                        /* mark the index as unsafe for old snapshots */
-                       if (!is_system_catalog)
-                           indexInfo->ii_BrokenHotChain = true;
+                       indexInfo->ii_BrokenHotChain = true;
                    }
                    else if (indexInfo->ii_BrokenHotChain)
                        indexIt = false;