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);