pathkeys fixes

diff --git a/src/backend/nodes/print.c b/src/backend/nodes/print.c
index f26d5100e34d0270b504a8f14c0f96d805366ed1..e8837dc7570b1180834fe481dcc4b58ee630ac02 100644 (file)
--- a/src/backend/nodes/print.c
+++ b/src/backend/nodes/print.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *   $Header: /cvsroot/pgsql/src/backend/nodes/print.c,v 1.22 1999/02/13 23:16:00 momjian Exp $
+ *   $Header: /cvsroot/pgsql/src/backend/nodes/print.c,v 1.23 1999/02/20 19:02:40 momjian Exp $
  *
  * HISTORY
  *   AUTHOR            DATE            MAJOR EVENT
@@ -213,20 +213,28 @@ print_expr(Node *expr, List *rtable)
 
 /*
  * print_pathkeys -
- *   temporary here. where is keys list of lists
+ *   pathkeys list of list of Var's
  */
 void
 print_pathkeys(List *pathkeys, List *rtable)
 {
-   List       *k;
+   List       *i, *k;
 
    printf("(");
-   foreach(k, pathkeys)
+   foreach(i, pathkeys)
    {
-       Node       *var = lfirst((List *) lfirst(k));
+       List pathkey = lfirst(i));
 
-       print_expr(var, rtable);
-       if (lnext(k))
+       printf("(");
+       foreach(k, pathkey)
+       {
+           Node       *var = lfirst(k);
+           print_expr(var, rtable);
+           if (lnext(k))
+               printf(", ");
+       }
+       printf(") ");
+       if (lnext(i))
            printf(", ");
    }
    printf(")\n");

diff --git a/src/backend/optimizer/path/pathkeys.c b/src/backend/optimizer/path/pathkeys.c
index f1ea6cbae68384b54a7967675d7b1930e148b77b..836b924ae1389ad3b735d3cadb7c4005b44bfe49 100644 (file)
--- a/src/backend/optimizer/path/pathkeys.c
+++ b/src/backend/optimizer/path/pathkeys.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *   $Header: /cvsroot/pgsql/src/backend/optimizer/path/pathkeys.c,v 1.4 1999/02/20 18:01:01 momjian Exp $
+ *   $Header: /cvsroot/pgsql/src/backend/optimizer/path/pathkeys.c,v 1.5 1999/02/20 19:02:41 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -54,7 +54,19 @@ static List *new_matching_subkeys(Var *subkey, List *considered_subkeys,
  * { {tab1.col1, tab2.col1} }.  This allows future joins to use either Var
  * as a pre-sorted key to prevent Mergejoins from having to re-sort the Path.
  * They are equal, so they are both primary sort keys.  This is why pathkeys
- * is a List of Lists.  -- bjm
+ * is a List of Lists.
+ *
+ * For multi-key sorts, if the outer is sorted by a multi-key index, the
+ * multi-key index remains after the join.  If the inner has a multi-key
+ * sort, only the primary key of the inner is added to the result.
+ * Mergejoins only join on the primary key.  Currently, non-primary keys
+ * in the pathkeys List are of limited value.
+ *
+ * HashJoin has similar functionality.  NestJoin does not perform sorting,
+ * and allows non-equajoins, so it does not allow useful pathkeys.
+ *
+ * -- bjm
+ * 
  */
  
 /****************************************************************************
@@ -92,10 +104,10 @@ static List *new_matching_subkeys(Var *subkey, List *considered_subkeys,
  */
 List *
 order_joinkeys_by_pathkeys(List *pathkeys,
-                       List *joinkeys,
-                       List *joinclauses,
-                       int outer_or_inner,
-                       List **matchedJoinClausesPtr)
+                           List *joinkeys,
+                           List *joinclauses,
+                           int outer_or_inner,
+                           List **matchedJoinClausesPtr)
 {
    List       *matched_joinkeys = NIL;
    List       *matched_joinclauses = NIL;
@@ -103,6 +115,10 @@ order_joinkeys_by_pathkeys(List *pathkeys,
    List       *i = NIL;
    int         matched_joinkey_index = -1;
 
+   /*
+    *  Reorder the joinkeys by picking out one that matches each pathkey,
+    *  and create a new joinkey/joinclause list in pathkey order
+    */
    foreach(i, pathkeys)
    {
        pathkey = lfirst(i);
@@ -118,10 +134,18 @@ order_joinkeys_by_pathkeys(List *pathkeys,
            matched_joinclauses = lappend(matched_joinclauses, joinclause);
        }
        else
-       {
+           /*  A pathkey could not be matched. */
+           break;
+   }
+
+   /*
+    *  Did we fail to match all the joinkeys?
+    *  Extra pathkeys are no problem.
+    */
+   if (length(joinkeys) != length(matched_joinkeys))
+   {
            *matchedJoinClausesPtr = NIL;
            return NIL;
-       }
    }
 
    *matchedJoinClausesPtr = matched_joinclauses;
@@ -133,6 +157,8 @@ order_joinkeys_by_pathkeys(List *pathkeys,
  * match_pathkey_joinkeys
  *   Returns the 0-based index into 'joinkeys' of the first joinkey whose
  *   outer or inner subkey matches any subkey of 'pathkey'.
+ *
+ * All these keys are equivalent, so any of them can match.  See above.
  */
 static int
 match_pathkey_joinkeys(List *pathkey,
@@ -141,8 +167,7 @@ match_pathkey_joinkeys(List *pathkey,
 {
    Var        *path_subkey;
    int         pos;
-   List       *i = NIL;
-   List       *x = NIL;
+   List       *i, *x;
    JoinKey    *jk;
 
    foreach(i, pathkey)
@@ -152,8 +177,7 @@ match_pathkey_joinkeys(List *pathkey,
        foreach(x, joinkeys)
        {
            jk = (JoinKey *) lfirst(x);
-           if (var_equal(path_subkey,
-                         extract_join_key(jk, outer_or_inner)))
+           if (var_equal(path_subkey, extract_join_key(jk, outer_or_inner)))
                return pos;
            pos++;
        }

diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c
index d94e124193e61d3c951469680cbcd406688bfcc2..7011f053c0ae11a0f5f6e2ecab6477c98555fca0 100644 (file)
--- a/src/backend/optimizer/util/pathnode.c
+++ b/src/backend/optimizer/util/pathnode.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *   $Header: /cvsroot/pgsql/src/backend/optimizer/util/pathnode.c,v 1.38 1999/02/20 18:01:02 momjian Exp $
+ *   $Header: /cvsroot/pgsql/src/backend/optimizer/util/pathnode.c,v 1.39 1999/02/20 19:02:42 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -205,7 +205,7 @@ better_path(Path *new_path, List *unique_paths, bool *is_new)
        {
            /*
             * Replace pathkeys that match exactly, {{1,2}}, {{1,2}}
-            * Replace pathkeys {{1,2}}with {{1,2,3}}} if the latter is not
+            * Replace pathkeys {{1,2}} with {{1,2,3}}} if the latter is not
             * more expensive and replace unordered path with ordered
             * path if it is not more expensive.  Favor sorted keys
             * over unsorted keys in the same way.

diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index f9818339b0cb054fcc088c0f8d91d52aa9ce760c..bf2e59d30cbc9677d8d8b73eb2a8bf432a288dfd 100644 (file)
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -6,7 +6,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: relation.h,v 1.27 1999/02/20 16:28:20 momjian Exp $
+ * $Id: relation.h,v 1.28 1999/02/20 19:02:43 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -142,8 +142,7 @@ typedef struct Path
 
    PathOrder   *pathorder;
 
-   List        *pathkeys;  /*
-                            * This is a List of List of Var nodes.
+   List        *pathkeys;  /* This is a List of List of Var nodes.
                             * See the top of optimizer/path/pathkeys.c
                             * for more information.
                             */