Remove some dead code in selfuncs.c

RelOptInfo.userid is the same for all relations in a given inheritance
tree, so the code in examine_variable() and example_simple_variable()
that repeats the ACL checks on the root parent rel instead of a given
leaf child relations need not recompute userid too.

Author: Amit Langote <amitlangote09@gmail.com>
Reported-by: Justin Pryzby <pryzby@telsasoft.com>
Discussion: https://postgr.es/m/20221210201753.GA27893@telsasoft.com

diff --git a/src/backend/optimizer/util/relnode.c b/src/backend/optimizer/util/relnode.c
index 75bc20c7c9884d24810050e5c545c763a3cd45fa..0a5632699d6f4fbb2b2c23fea95641c51103f1a3 100644 (file)
--- a/src/backend/optimizer/util/relnode.c
+++ b/src/backend/optimizer/util/relnode.c
@@ -500,7 +500,6 @@ find_join_rel(PlannerInfo *root, Relids relids)
  *
  * Otherwise these fields are left invalid, so GetForeignJoinPaths will not be
  * called for the join relation.
- *
  */
 static void
 set_foreign_rel_properties(RelOptInfo *joinrel, RelOptInfo *outer_rel,

diff --git a/src/backend/utils/adt/selfuncs.c b/src/backend/utils/adt/selfuncs.c
index 57de51f0db20b439f4880e523e654ae54c830921..4e4888dde4d676b2edc106a711c7979ef826ddaf 100644 (file)
--- a/src/backend/utils/adt/selfuncs.c
+++ b/src/backend/utils/adt/selfuncs.c
@@ -5080,6 +5080,18 @@ examine_variable(PlannerInfo *root, Node *node, int varRelid,
                 */
                ListCell   *ilist;
                ListCell   *slist;
+               Oid                     userid;
+
+               /*
+                * Determine the user ID to use for privilege checks: either
+                * onerel->userid if it's set (e.g., in case we're accessing the table
+                * via a view), or the current user otherwise.
+                *
+                * If we drill down to child relations, we keep using the same userid:
+                * it's going to be the same anyway, due to how we set up the relation
+                * tree (q.v. build_simple_rel).
+                */
+               userid = OidIsValid(onerel->userid) ? onerel->userid : GetUserId();
 
                foreach(ilist, onerel->indexlist)
                {
@@ -5150,18 +5162,10 @@ examine_variable(PlannerInfo *root, Node *node, int varRelid,
                                                        {
                                                                /* Get index's table for permission check */
                                                                RangeTblEntry *rte;
-                                                               Oid                     userid;
 
                                                                rte = planner_rt_fetch(index->rel->relid, root);
                                                                Assert(rte->rtekind == RTE_RELATION);
 
-                                                               /*
-                                                                * Use onerel->userid if it's set, in case
-                                                                * we're accessing the table via a view.
-                                                                */
-                                                               userid = OidIsValid(onerel->userid) ?
-                                                                       onerel->userid : GetUserId();
-
                                                                /*
                                                                 * For simplicity, we insist on the whole
                                                                 * table being selectable, rather than trying
@@ -5212,9 +5216,6 @@ examine_variable(PlannerInfo *root, Node *node, int varRelid,
                                                                                rte = planner_rt_fetch(varno, root);
                                                                                Assert(rte->rtekind == RTE_RELATION);
 
-                                                                               userid = OidIsValid(onerel->userid) ?
-                                                                                       onerel->userid : GetUserId();
-
                                                                                vardata->acl_ok =
                                                                                        rte->securityQuals == NIL &&
                                                                                        (pg_class_aclcheck(rte->relid,
@@ -5281,8 +5282,6 @@ examine_variable(PlannerInfo *root, Node *node, int varRelid,
                                /* found a match, see if we can extract pg_statistic row */
                                if (equal(node, expr))
                                {
-                                       Oid                     userid;
-
                                        /*
                                         * XXX Not sure if we should cache the tuple somewhere.
                                         * Now we just create a new copy every time.
@@ -5292,13 +5291,6 @@ examine_variable(PlannerInfo *root, Node *node, int varRelid,
 
                                        vardata->freefunc = ReleaseDummy;
 
-                                       /*
-                                        * Use onerel->userid if it's set, in case we're accessing
-                                        * the table via a view.
-                                        */
-                                       userid = OidIsValid(onerel->userid) ?
-                                               onerel->userid : GetUserId();
-
                                        /*
                                         * For simplicity, we insist on the whole table being
                                         * selectable, rather than trying to identify which
@@ -5345,9 +5337,6 @@ examine_variable(PlannerInfo *root, Node *node, int varRelid,
                                                        rte = planner_rt_fetch(varno, root);
                                                        Assert(rte->rtekind == RTE_RELATION);
 
-                                                       userid = OidIsValid(onerel->userid) ?
-                                                               onerel->userid : GetUserId();
-
                                                        vardata->acl_ok =
                                                                rte->securityQuals == NIL &&
                                                                (pg_class_aclcheck(rte->relid,
@@ -5486,9 +5475,10 @@ examine_simple_variable(PlannerInfo *root, Var *var,
                                rte = planner_rt_fetch(varno, root);
                                Assert(rte->rtekind == RTE_RELATION);
 
-                               userid = OidIsValid(onerel->userid) ?
-                                       onerel->userid : GetUserId();
-
+                               /*
+                                * Fine to use the same userid as it's the same in all
+                                * relations of a given inheritance tree.
+                                */
                                vardata->acl_ok =
                                        rte->securityQuals == NIL &&
                                        ((pg_class_aclcheck(rte->relid, userid,