1 files changed, 107 insertions, 0 deletions
diff --git a/src/backend/optimizer/util/joininfo.c b/src/backend/optimizer/util/joininfo.c
new file mode 100644
index 00000000000..85416db8b33
--- /dev/null
+++ b/src/backend/optimizer/util/joininfo.c
@@ -0,0 +1,107 @@
+/*-------------------------------------------------------------------------
+ *
+ * joininfo.c--
+ *    JoinInfo node manipulation routines
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *    $Header: /cvsroot/pgsql/src/backend/optimizer/util/joininfo.c,v 1.1.1.1 1996/07/09 06:21:38 scrappy Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+
+#include "nodes/relation.h"
+
+#include "optimizer/internal.h"
+#include "optimizer/var.h"
+#include "optimizer/clauses.h"
+
+
+/*    
+ * joininfo-member--
+ *    Determines whether a node has already been created for a join
+ *    between a set of join relations and the relation described by
+ *    'joininfo-list'.
+ *    
+ * 'join-relids' is a list of relids corresponding to the join relation
+ * 'joininfo-list' is the list of joininfo nodes against which this is 
+ *   		checked
+ *    
+ * Returns the corresponding node in 'joininfo-list' if such a node
+ * exists.
+ *    
+ */
+JInfo *
+joininfo_member(List *join_relids, List *joininfo_list)
+{
+    List *i = NIL;
+    List *other_rels = NIL;
+
+    foreach(i,joininfo_list) {
+	other_rels = lfirst(i);
+	if(same(join_relids, ((JInfo*)other_rels)->otherrels))
+	    return((JInfo*)other_rels);
+    }
+    return((JInfo*)NULL);
+}
+
+
+/*    
+ * find-joininfo-node--
+ *    Find the joininfo node within a relation entry corresponding
+ *    to a join between 'this_rel' and the relations in 'join-relids'.  A
+ *    new node is created and added to the relation entry's joininfo
+ *    field if the desired one can't be found.
+ *    
+ * Returns a joininfo node.
+ *    
+ */
+JInfo *
+find_joininfo_node(Rel *this_rel, List *join_relids)
+{
+    JInfo *joininfo = joininfo_member(join_relids,
+				      this_rel->joininfo);
+    if( joininfo == NULL ) {
+	joininfo = makeNode(JInfo);
+	joininfo->otherrels = join_relids;
+	joininfo->jinfoclauseinfo = NIL;
+	joininfo->mergesortable = false;
+	joininfo->hashjoinable = false;
+	joininfo->inactive = false;
+	this_rel->joininfo = lcons(joininfo, this_rel->joininfo);
+    }
+    return(joininfo);
+}
+
+/*    
+ * other-join-clause-var--
+ *    Determines whether a var node is contained within a joinclause
+ *    of the form(op var var).
+ *    
+ * Returns the other var node in the joinclause if it is, nil if not.
+ *    
+ */
+Var *
+other_join_clause_var(Var *var, Expr *clause)
+{
+     Var *retval;
+     Var *l, *r;
+
+     retval = (Var*) NULL;
+
+     if( var != NULL  && join_clause_p((Node*)clause)) {
+	  l = (Var *) get_leftop(clause);
+	  r = (Var *) get_rightop(clause);
+
+	  if(var_equal(var, l)) {
+	       retval = r;
+	  } else if(var_equal(var, r)) {
+	       retval = l;
+	  }
+     }
+
+     return(retval);
+}