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

This reverts commit 8835284e0d903156632f76eea941cf5c592717ec 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 79b96a07d8d052638c586258ae6c88ffde6c54b0..487dbbf24d247251d3078839009687f7c96af7bc 100644 (file)
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -1423,13 +1423,6 @@ 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,
@@ -1489,13 +1482,7 @@ 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,
@@ -1505,7 +1492,6 @@ IndexBuildHeapScan(Relation heapRelation,
                                   IndexBuildCallback callback,
                                   void *callback_state)
 {
-       bool            is_system_catalog;
        HeapScanDesc scan;
        HeapTuple       heapTuple;
        Datum           values[INDEX_MAX_KEYS];
@@ -1525,9 +1511,6 @@ 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.
@@ -1666,8 +1649,7 @@ 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;
@@ -1756,8 +1738,7 @@ 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;
@@ -2371,35 +2352,27 @@ reindex_index(Oid indexId)
         * We can also reset indcheckxmin, because we have now done a
         * non-concurrent index build, *except* in the case where index_build
         * found some still-broken HOT chains.
-        *
-        * When reindexing a system catalog, don't do any of this --- it would be
-        * particularly risky to try to modify pg_index while we are reindexing
-        * pg_index itself.  We don't support CREATE INDEX CONCURRENTLY on system
-        * catalogs anyway, and they should never have indcheckxmin set either.
         */
-       if (!IsSystemRelation(heapRelation))
-       {
-               pg_index = heap_open(IndexRelationId, RowExclusiveLock);
+       pg_index = heap_open(IndexRelationId, RowExclusiveLock);
 
-               indexTuple = SearchSysCacheCopy(INDEXRELID,
-                                                                               ObjectIdGetDatum(indexId),
-                                                                               0, 0, 0);
-               if (!HeapTupleIsValid(indexTuple))
-                       elog(ERROR, "cache lookup failed for index %u", indexId);
-               indexForm = (Form_pg_index) GETSTRUCT(indexTuple);
+       indexTuple = SearchSysCacheCopy(INDEXRELID,
+                                                                       ObjectIdGetDatum(indexId),
+                                                                       0, 0, 0);
+       if (!HeapTupleIsValid(indexTuple))
+               elog(ERROR, "cache lookup failed for index %u", indexId);
+       indexForm = (Form_pg_index) GETSTRUCT(indexTuple);
 
-               if (!indexForm->indisvalid || !indexForm->indisready ||
-                       (indexForm->indcheckxmin && !indexInfo->ii_BrokenHotChain))
-               {
-                       indexForm->indisvalid = true;
-                       indexForm->indisready = true;
-                       if (!indexInfo->ii_BrokenHotChain)
-                               indexForm->indcheckxmin = false;
-                       simple_heap_update(pg_index, &indexTuple->t_self, indexTuple);
-                       CatalogUpdateIndexes(pg_index, indexTuple);
-               }
-               heap_close(pg_index, RowExclusiveLock);
+       if (!indexForm->indisvalid || !indexForm->indisready ||
+               (indexForm->indcheckxmin && !indexInfo->ii_BrokenHotChain))
+       {
+               indexForm->indisvalid = true;
+               indexForm->indisready = true;
+               if (!indexInfo->ii_BrokenHotChain)
+                       indexForm->indcheckxmin = false;
+               simple_heap_update(pg_index, &indexTuple->t_self, indexTuple);
+               CatalogUpdateIndexes(pg_index, indexTuple);
        }
+       heap_close(pg_index, RowExclusiveLock);
 
        /* Close rels, but keep locks */
        index_close(iRel, NoLock);