Ensure acquire_inherited_sample_rows sets its output parameters.

The totalrows/totaldeadrows outputs were left uninitialized in cases
where we find no analyzable child tables of a partitioned table.  This
could lead to setting the partitioned table's pg_class.reltuples value
to garbage.  It's not clear that that would have any very bad effects
in practice, but fix it anyway because it's making valgrind unhappy.

Reported and diagnosed by Alexander Lakhin (bug #17880).

Discussion: https://postgr.es/m/17880-9282037c923d856e@postgresql.org

diff --git a/src/backend/commands/analyze.c b/src/backend/commands/analyze.c
index 65750958bb2cb3fa5d148dd58236e2ce84af9463..bec9c8b42771a9c14c3ed9563879fca2a38ea354 100644 (file)
--- a/src/backend/commands/analyze.c
+++ b/src/backend/commands/analyze.c
@@ -1389,6 +1389,10 @@ acquire_inherited_sample_rows(Relation onerel, int elevel,
        ListCell   *lc;
        bool            has_child;
 
+       /* Initialize output parameters to zero now, in case we exit early */
+       *totalrows = 0;
+       *totaldeadrows = 0;
+
        /*
         * Find all members of inheritance set.  We only need AccessShareLock on
         * the children.
@@ -1522,8 +1526,6 @@ acquire_inherited_sample_rows(Relation onerel, int elevel,
        pgstat_progress_update_param(PROGRESS_ANALYZE_CHILD_TABLES_TOTAL,
                                                                 nrels);
        numrows = 0;
-       *totalrows = 0;
-       *totaldeadrows = 0;
        for (i = 0; i < nrels; i++)
        {
                Relation        childrel = rels[i];