1 files changed, 122 insertions, 0 deletions
diff --git a/src/backend/optimizer/path/mergeutils.c b/src/backend/optimizer/path/mergeutils.c
new file mode 100644
index 00000000000..d5f0fdcb65b
--- /dev/null
+++ b/src/backend/optimizer/path/mergeutils.c
@@ -0,0 +1,122 @@
+/*-------------------------------------------------------------------------
+ *
+ * mergeutils.c--
+ *    Utilities for finding applicable merge clauses and pathkeys
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *    $Header: /cvsroot/pgsql/src/backend/optimizer/path/Attic/mergeutils.c,v 1.1.1.1 1996/07/09 06:21:36 scrappy Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "nodes/pg_list.h"
+#include "nodes/relation.h"
+
+#include "optimizer/internal.h"
+#include "optimizer/paths.h"
+#include "optimizer/clauses.h"
+#include "optimizer/ordering.h"
+
+/*    
+ * group-clauses-by-order--
+ *    If a join clause node in 'clauseinfo-list' is mergesortable, store
+ *    it within a mergeinfo node containing other clause nodes with the same
+ *    mergesort ordering.
+ *    
+ * 'clauseinfo-list' is the list of clauseinfo nodes
+ * 'inner-relid' is the relid of the inner join relation
+ *    
+ * Returns the new list of mergeinfo nodes.
+ *    
+ */
+List *
+group_clauses_by_order(List *clauseinfo_list,
+		       int inner_relid)
+{
+    List *mergeinfo_list = NIL;
+    List *xclauseinfo = NIL;
+    
+    foreach (xclauseinfo, clauseinfo_list) {
+	CInfo *clauseinfo = (CInfo *)lfirst(xclauseinfo);
+	MergeOrder *merge_ordering = clauseinfo->mergesortorder;
+	
+	if (merge_ordering) {
+	    /*
+	     * Create a new mergeinfo node and add it to
+	     * 'mergeinfo-list' if one does not yet exist for this
+	     * merge ordering.
+	     */
+	    PathOrder p_ordering;
+	    MInfo *xmergeinfo;
+	    Expr *clause = clauseinfo->clause;
+	    Var *leftop = get_leftop (clause);
+	    Var *rightop = get_rightop (clause);
+	    JoinKey *keys;
+
+	    p_ordering.ordtype = MERGE_ORDER;
+	    p_ordering.ord.merge = merge_ordering;
+	    xmergeinfo =
+		match_order_mergeinfo(&p_ordering, mergeinfo_list);
+	    if (inner_relid == leftop->varno) {
+		keys = makeNode(JoinKey);
+		keys->outer = rightop;
+		keys->inner = leftop;
+	    } else {
+		keys = makeNode(JoinKey);
+		keys->outer = leftop;
+		keys->inner = rightop;
+	    } 
+	    
+	    if (xmergeinfo==NULL) {
+		xmergeinfo = makeNode(MInfo);
+
+		xmergeinfo->m_ordering = merge_ordering;
+		mergeinfo_list = lcons(xmergeinfo,
+				      mergeinfo_list);
+	    }
+	    
+	    ((JoinMethod *)xmergeinfo)->clauses =
+		lcons(clause,
+		     ((JoinMethod *)xmergeinfo)->clauses);
+	    ((JoinMethod *)xmergeinfo)->jmkeys =
+		lcons(keys,
+		     ((JoinMethod *)xmergeinfo)->jmkeys);
+	}
+    }
+    return(mergeinfo_list);
+}
+
+
+/*    
+ * match-order-mergeinfo--
+ *    Searches the list 'mergeinfo-list' for a mergeinfo node whose order
+ *    field equals 'ordering'.
+ *    
+ * Returns the node if it exists.
+ *    
+ */
+MInfo *
+match_order_mergeinfo(PathOrder *ordering, List *mergeinfo_list)
+{
+    MergeOrder *xmergeorder;
+    List *xmergeinfo = NIL;
+
+    foreach(xmergeinfo, mergeinfo_list) {
+	MInfo *mergeinfo = (MInfo*)lfirst(xmergeinfo);
+
+	xmergeorder = mergeinfo->m_ordering;
+
+	if ((ordering->ordtype==MERGE_ORDER &&
+	     equal_merge_merge_ordering(ordering->ord.merge, xmergeorder)) ||
+	    (ordering->ordtype==SORTOP_ORDER &&
+	     equal_path_merge_ordering(ordering->ord.sortop, xmergeorder))) {
+
+	    return (mergeinfo);
+	}
+    }
+    return((MInfo*) NIL);
+}