Promote assertion about !ReindexIsProcessingIndex to runtime error.

When this assertion was installed (in commit d2f60a3ab), I thought
it was only for catching server logic errors that caused accesses to
catalogs that were undergoing index rebuilds.  However, it will also
fire in case of a user-defined index expression that attempts to
access its own table.  We occasionally see reports of people trying
to do that, and typically getting unintelligible low-level errors
as a result.  We can provide a more on-point message by making this
a regular runtime check.

While at it, adjust the similar error check in
systable_beginscan_ordered to use the same message text.  That one
is (probably) not reachable without a coding bug, but we might as
well use a translatable message if we have one.

Per bug #18363 from Alexander Lakhin.  Back-patch to all supported
branches.

Discussion: https://postgr.es/m/18363-e3598a5a572d0699@postgresql.org

diff --git a/src/backend/access/index/genam.c b/src/backend/access/index/genam.c
index b9a3206963289ded6f7a213ee7010afcbebf76c3..7b6131b9e098a41b271ce254d521d5bfc247159e 100644 (file)
--- a/src/backend/access/index/genam.c
+++ b/src/backend/access/index/genam.c
@@ -653,8 +653,10 @@ systable_beginscan_ordered(Relation heapRelation,
 
    /* REINDEX can probably be a hard error here ... */
    if (ReindexIsProcessingIndex(RelationGetRelid(indexRelation)))
-       elog(ERROR, "cannot do ordered scan on index \"%s\", because it is being reindexed",
-            RelationGetRelationName(indexRelation));
+       ereport(ERROR,
+               (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+                errmsg("cannot access index \"%s\" while it is being reindexed",
+                       RelationGetRelationName(indexRelation))));
    /* ... but we only throw a warning about violating IgnoreSystemIndexes */
    if (IgnoreSystemIndexes)
        elog(WARNING, "using index \"%s\" despite IgnoreSystemIndexes",

diff --git a/src/backend/access/index/indexam.c b/src/backend/access/index/indexam.c
index bbd499abcfb8e8ca2e5d712c18834101b5a230ea..14baacd61f484ebde1464d3a6cbb371f90e2aa8f 100644 (file)
--- a/src/backend/access/index/indexam.c
+++ b/src/backend/access/index/indexam.c
@@ -70,18 +70,23 @@
  * Note: the ReindexIsProcessingIndex() check in RELATION_CHECKS is there
  * to check that we don't try to scan or do retail insertions into an index
  * that is currently being rebuilt or pending rebuild.  This helps to catch
- * things that don't work when reindexing system catalogs.  The assertion
+ * things that don't work when reindexing system catalogs, as well as prevent
+ * user errors like index expressions that access their own tables.  The check
  * doesn't prevent the actual rebuild because we don't use RELATION_CHECKS
  * when calling the index AM's ambuild routine, and there is no reason for
  * ambuild to call its subsidiary routines through this file.
  * ----------------------------------------------------------------
  */
 #define RELATION_CHECKS \
-( \
-   AssertMacro(RelationIsValid(indexRelation)), \
-   AssertMacro(PointerIsValid(indexRelation->rd_indam)), \
-   AssertMacro(!ReindexIsProcessingIndex(RelationGetRelid(indexRelation))) \
-)
+do { \
+   Assert(RelationIsValid(indexRelation)); \
+   Assert(PointerIsValid(indexRelation->rd_indam)); \
+   if (unlikely(ReindexIsProcessingIndex(RelationGetRelid(indexRelation)))) \
+       ereport(ERROR, \
+               (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), \
+                errmsg("cannot access index \"%s\" while it is being reindexed", \
+                       RelationGetRelationName(indexRelation)))); \
+} while(0)
 
 #define SCAN_CHECKS \
 ( \