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 7b1a0f9cbcc7335b3c05a51a73e8617cd9ba2faa..137f7239d53078ec30eb2e862f5fa9f2d9092632 100644 (file)
--- a/src/backend/commands/analyze.c
+++ b/src/backend/commands/analyze.c
@@ -1409,6 +1409,10 @@ 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.
@@ -1542,8 +1546,6 @@ 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];