Don't pass down nonnullable_vars while reducing outer joins.

We weren't actually using the passed-down list for anything, other
than computing the new value to be passed down further.  I (tgl)
probably had the idea that we'd need this data eventually; but
no use-case has emerged in a good long while, so let's just stop
expending useless cycles here.

Richard Guo

Discussion: https://postgr.es/m/CAMbWs48KLy9aBb=sZ5MoNmnqAcGHaW_JTGWLCgoE_uMW7S6C-A@mail.gmail.com

diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c
index 41c7066d90a3fe8031c30f231e605be731c7bcc5..b4b9099eb6b3fa6942e0a90eca8db0282a0c0c4b 100644 (file)
--- a/src/backend/optimizer/prep/prepjointree.c
+++ b/src/backend/optimizer/prep/prepjointree.c
@@ -117,7 +117,6 @@ static void reduce_outer_joins_pass2(Node *jtnode,
                                                                         reduce_outer_joins_state *state,
                                                                         PlannerInfo *root,
                                                                         Relids nonnullable_rels,
-                                                                        List *nonnullable_vars,
                                                                         List *forced_null_vars);
 static Node *remove_useless_results_recurse(PlannerInfo *root, Node *jtnode);
 static int     get_result_relid(PlannerInfo *root, Node *jtnode);
@@ -2693,7 +2692,7 @@ reduce_outer_joins(PlannerInfo *root)
                elog(ERROR, "so where are the outer joins?");
 
        reduce_outer_joins_pass2((Node *) root->parse->jointree,
-                                                        state, root, NULL, NIL, NIL);
+                                                        state, root, NULL, NIL);
 }
 
 /*
@@ -2770,7 +2769,6 @@ reduce_outer_joins_pass1(Node *jtnode)
  *     state: state data collected by phase 1 for this node
  *     root: toplevel planner state
  *     nonnullable_rels: set of base relids forced non-null by upper quals
- *     nonnullable_vars: list of Vars forced non-null by upper quals
  *     forced_null_vars: list of Vars forced null by upper quals
  */
 static void
@@ -2778,7 +2776,6 @@ reduce_outer_joins_pass2(Node *jtnode,
                                                 reduce_outer_joins_state *state,
                                                 PlannerInfo *root,
                                                 Relids nonnullable_rels,
-                                                List *nonnullable_vars,
                                                 List *forced_null_vars)
 {
        /*
@@ -2795,16 +2792,12 @@ reduce_outer_joins_pass2(Node *jtnode,
                ListCell   *l;
                ListCell   *s;
                Relids          pass_nonnullable_rels;
-               List       *pass_nonnullable_vars;
                List       *pass_forced_null_vars;
 
                /* Scan quals to see if we can add any constraints */
                pass_nonnullable_rels = find_nonnullable_rels(f->quals);
                pass_nonnullable_rels = bms_add_members(pass_nonnullable_rels,
                                                                                                nonnullable_rels);
-               pass_nonnullable_vars = find_nonnullable_vars(f->quals);
-               pass_nonnullable_vars = list_concat(pass_nonnullable_vars,
-                                                                                       nonnullable_vars);
                pass_forced_null_vars = find_forced_null_vars(f->quals);
                pass_forced_null_vars = list_concat(pass_forced_null_vars,
                                                                                        forced_null_vars);
@@ -2817,7 +2810,6 @@ reduce_outer_joins_pass2(Node *jtnode,
                        if (sub_state->contains_outer)
                                reduce_outer_joins_pass2(lfirst(l), sub_state, root,
                                                                                 pass_nonnullable_rels,
-                                                                                pass_nonnullable_vars,
                                                                                 pass_forced_null_vars);
                }
                bms_free(pass_nonnullable_rels);
@@ -2830,8 +2822,6 @@ reduce_outer_joins_pass2(Node *jtnode,
                JoinType        jointype = j->jointype;
                reduce_outer_joins_state *left_state = linitial(state->sub_states);
                reduce_outer_joins_state *right_state = lsecond(state->sub_states);
-               List       *local_nonnullable_vars = NIL;
-               bool            computed_local_nonnullable_vars = false;
 
                /* Can we simplify this join? */
                switch (jointype)
@@ -2906,17 +2896,18 @@ reduce_outer_joins_pass2(Node *jtnode,
                 */
                if (jointype == JOIN_LEFT)
                {
+                       List       *nonnullable_vars;
                        List       *overlap;
 
-                       local_nonnullable_vars = find_nonnullable_vars(j->quals);
-                       computed_local_nonnullable_vars = true;
+                       /* Find Vars in j->quals that must be non-null in joined rows */
+                       nonnullable_vars = find_nonnullable_vars(j->quals);
 
                        /*
-                        * It's not sufficient to check whether local_nonnullable_vars and
+                        * It's not sufficient to check whether nonnullable_vars and
                         * forced_null_vars overlap: we need to know if the overlap
                         * includes any RHS variables.
                         */
-                       overlap = list_intersection(local_nonnullable_vars,
+                       overlap = list_intersection(nonnullable_vars,
                                                                                forced_null_vars);
                        if (overlap != NIL &&
                                bms_overlap(pull_varnos(root, (Node *) overlap),
@@ -2941,7 +2932,6 @@ reduce_outer_joins_pass2(Node *jtnode,
                        Relids          local_nonnullable_rels;
                        List       *local_forced_null_vars;
                        Relids          pass_nonnullable_rels;
-                       List       *pass_nonnullable_vars;
                        List       *pass_forced_null_vars;
 
                        /*
@@ -2968,16 +2958,12 @@ reduce_outer_joins_pass2(Node *jtnode,
                        if (jointype != JOIN_FULL)
                        {
                                local_nonnullable_rels = find_nonnullable_rels(j->quals);
-                               if (!computed_local_nonnullable_vars)
-                                       local_nonnullable_vars = find_nonnullable_vars(j->quals);
                                local_forced_null_vars = find_forced_null_vars(j->quals);
                                if (jointype == JOIN_INNER || jointype == JOIN_SEMI)
                                {
                                        /* OK to merge upper and local constraints */
                                        local_nonnullable_rels = bms_add_members(local_nonnullable_rels,
                                                                                                                         nonnullable_rels);
-                                       local_nonnullable_vars = list_concat(local_nonnullable_vars,
-                                                                                                                nonnullable_vars);
                                        local_forced_null_vars = list_concat(local_forced_null_vars,
                                                                                                                 forced_null_vars);
                                }
@@ -2995,26 +2981,22 @@ reduce_outer_joins_pass2(Node *jtnode,
                                {
                                        /* pass union of local and upper constraints */
                                        pass_nonnullable_rels = local_nonnullable_rels;
-                                       pass_nonnullable_vars = local_nonnullable_vars;
                                        pass_forced_null_vars = local_forced_null_vars;
                                }
                                else if (jointype != JOIN_FULL) /* ie, LEFT or ANTI */
                                {
                                        /* can't pass local constraints to non-nullable side */
                                        pass_nonnullable_rels = nonnullable_rels;
-                                       pass_nonnullable_vars = nonnullable_vars;
                                        pass_forced_null_vars = forced_null_vars;
                                }
                                else
                                {
                                        /* no constraints pass through JOIN_FULL */
                                        pass_nonnullable_rels = NULL;
-                                       pass_nonnullable_vars = NIL;
                                        pass_forced_null_vars = NIL;
                                }
                                reduce_outer_joins_pass2(j->larg, left_state, root,
                                                                                 pass_nonnullable_rels,
-                                                                                pass_nonnullable_vars,
                                                                                 pass_forced_null_vars);
                        }
 
@@ -3024,19 +3006,16 @@ reduce_outer_joins_pass2(Node *jtnode,
                                {
                                        /* pass appropriate constraints, per comment above */
                                        pass_nonnullable_rels = local_nonnullable_rels;
-                                       pass_nonnullable_vars = local_nonnullable_vars;
                                        pass_forced_null_vars = local_forced_null_vars;
                                }
                                else
                                {
                                        /* no constraints pass through JOIN_FULL */
                                        pass_nonnullable_rels = NULL;
-                                       pass_nonnullable_vars = NIL;
                                        pass_forced_null_vars = NIL;
                                }
                                reduce_outer_joins_pass2(j->rarg, right_state, root,
                                                                                 pass_nonnullable_rels,
-                                                                                pass_nonnullable_vars,
                                                                                 pass_forced_null_vars);
                        }
                        bms_free(local_nonnullable_rels);