Add missing NULL check when building Result Cache paths

david-rowley · david-rowley · commit 99c5852e20a0 · 2021-05-24T12:37:11.000+12:00
Code added in 9e21537 to disable building of Result Cache paths when not all join conditions are part of the parameterization of a unique join failed to first check if the inner path's param_info was set before checking the param_info's ppi_clauses. Add a check for NULL values here and just bail on trying to build the path if param_info is NULL. lateral_vars are not considered when deciding if the join is unique, so we're not missing out on doing the optimization when there are lateral_vars and no param_info. Reported-by: Coverity, via Tom Lane Discussion: https://postgr.es/m/457998.1621779290@sss.pgh.pa.us
diff --git a/src/backend/optimizer/path/joinpath.c b/src/backend/optimizer/path/joinpath.c
@@ -530,8 +530,9 @@ get_resultcache_path(PlannerInfo *root, RelOptInfo *innerrel,
 	 * considering doing that?
 	 */
 	if (extra->inner_unique &&
-		list_length(inner_path->param_info->ppi_clauses) <
-		list_length(extra->restrictlist))
+		(inner_path->param_info == NULL ||
+		 list_length(inner_path->param_info->ppi_clauses) <
+		 list_length(extra->restrictlist)))
 		return NULL;
 
 	/*
