fix handling of inner/outer sortkeys in set_joinpath_distribution()

We must not reset inner/outer sortkeys unless the path is actually
redistributed. When a redistribution is not needed, the merge join
needs the original values. Otherwise this results in errors like

    ERROR: inner pathkeys do not match mergeclauses
    ERROR: outer pathkeys do not match mergeclauses

diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c
index 4077b8770b9fa7739f3927bde504c11adb90c906..c0ff99829cd6ad80ed14ee70ae5e902e3913a9e8 100644 (file)
--- a/src/backend/optimizer/util/pathnode.c
+++ b/src/backend/optimizer/util/pathnode.c
@@ -1974,6 +1974,9 @@ not_allowed_join:
                                                (Node *) new_inner_key,
                                                nodes,
                                                restrictNodes);
+
+                               if (IsA(pathnode, MergePath))
+                                       ((MergePath*)pathnode)->innersortkeys = NIL;
                        }
                        /*
                         * Redistribute join by hash, and, if jointype allows, create
@@ -1990,6 +1993,9 @@ not_allowed_join:
                                                (Node *) new_outer_key,
                                                nodes,
                                                restrictNodes);
+
+                               if (IsA(pathnode, MergePath))
+                                       ((MergePath*)pathnode)->outersortkeys = NIL;
                        }
                        targetd = makeNode(Distribution);
                        targetd->distributionType = distType;
@@ -2005,8 +2011,8 @@ not_allowed_join:
                         */
                        if (IsA(pathnode, MergePath))
                        {
-                               ((MergePath*)pathnode)->innersortkeys = NIL;
-                               ((MergePath*)pathnode)->outersortkeys = NIL;
+                               // ((MergePath*)pathnode)->innersortkeys = NIL;
+                               // ((MergePath*)pathnode)->outersortkeys = NIL;
                        }
 
                        /*
@@ -2040,6 +2046,7 @@ not_allowed_join:
         * relations.
         */
        if (innerd)
+       {
                pathnode->innerjoinpath = redistribute_path(root,
                                                                                                        pathnode->innerjoinpath,
                                                                                                        innerpathkeys,
@@ -2047,7 +2054,13 @@ not_allowed_join:
                                                                                                        NULL,
                                                                                                        NULL,
                                                                                                        NULL);
+
+               if (IsA(pathnode, MergePath))
+                       ((MergePath*)pathnode)->innersortkeys = NIL;
+       }
+
        if (outerd)
+       {
                pathnode->outerjoinpath = redistribute_path(root,
                                                                                                        pathnode->outerjoinpath,
                                                                                                        outerpathkeys,
@@ -2055,6 +2068,12 @@ not_allowed_join:
                                                                                                        NULL,
                                                                                                        NULL,
                                                                                                        NULL);
+                                                                                                       
+
+               if (IsA(pathnode, MergePath))
+                       ((MergePath*)pathnode)->outersortkeys = NIL;
+       }
+
        return alternate;
 }
 #endif