Allow treating TABLESAMPLE scans as parallel-safe.

This was the intention all along, but an extraneous "return;" in
set_rel_consider_parallel() caused sampled rels to never be marked
consider_parallel.

Since we don't have any partial tablesample path/plan type yet, there's
no possibility of parallelizing the sample scan itself; but this fix
allows such a scan to appear below a parallel join, for example.

diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index 2e4b670e069716d66155e5c9b19797064ab5d4dc..535d2e69b2b166355cba4f32f906a223cd927cf7 100644 (file)
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -538,7 +538,6 @@ set_rel_consider_parallel(PlannerInfo *root, RelOptInfo *rel,
                                if (has_parallel_hazard((Node *) rte->tablesample->args,
                                                                                false))
                                        return;
-                               return;
                        }
 
                        /*