Postgres95 1.01 Distribution - Virgin SourcesPG95-1_01

1 files changed, 193 insertions, 0 deletions

diff --git a/src/backend/optimizer/util/keys.c b/src/backend/optimizer/util/keys.c
new file mode 100644
index 00000000000..ac0915b9096
--- /dev/null
+++ b/src/backend/optimizer/util/keys.c
@@ -0,0 +1,193 @@
+/*-------------------------------------------------------------------------
+ *
+ * keys.c--
+ *    Key manipulation routines
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *    $Header: /cvsroot/pgsql/src/backend/optimizer/util/Attic/keys.c,v 1.1.1.1 1996/07/09 06:21:38 scrappy Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#include "postgres.h"
+#include "nodes/pg_list.h"
+#include "nodes/nodes.h"
+#include "nodes/relation.h"
+#include "utils/elog.h"
+
+#include "optimizer/internal.h"
+#include "optimizer/keys.h"
+#include "optimizer/tlist.h"
+
+
+static Expr *matching2_tlvar(int var, List *tlist, bool (*test)());
+
+/*    
+ * 1. index key
+ * 	one of:
+ * 		attnum
+ * 		(attnum arrayindex)
+ * 2. path key
+ * 	(subkey1 ... subkeyN)
+ * 	where subkeyI is a var node
+ *    	note that the 'Keys field is a list of these
+ * 3. join key
+ * 	(outer-subkey inner-subkey)
+ * 		where each subkey is a var node
+ * 4. sort key
+ * 	one of:
+ * 		SortKey node
+ * 		number
+ * 		nil
+ * 	(may also refer to the 'SortKey field of a SortKey node,
+ * 	 which looks exactly like an index key)
+ *    
+ */
+
+/*    
+ * match-indexkey-operand--
+ *    Returns t iff an index key 'index-key' matches the given clause 
+ *    operand.
+ *    
+ */
+bool
+match_indexkey_operand(int indexkey, Var *operand, Rel *rel)
+{
+    if (IsA (operand,Var) &&
+	(lfirsti(rel->relids) == operand->varno) &&
+	equal_indexkey_var(indexkey,operand))
+	return(true);
+    else
+	return(false);
+}
+
+/*    
+ * equal_indexkey_var--
+ *    Returns t iff an index key 'index-key' matches the corresponding 
+ *    fields of var node 'var'.
+ *    
+ */
+bool
+equal_indexkey_var(int index_key, Var *var)
+{
+    if (index_key == var->varattno)
+	return(true);
+    else
+	return(false);
+}
+
+/*    
+ * extract-subkey--
+ *   Returns the subkey in a join key corresponding to the outer or inner
+ *   lelation.
+ *    
+ */
+Var *
+extract_subkey(JoinKey *jk, int which_subkey)
+{
+    Var *retval;
+
+    switch (which_subkey) {
+    case OUTER: 
+	retval = jk->outer;
+	break;
+    case INNER: 
+	retval = jk->inner;
+	break;
+    default:			/* do nothing */
+	elog(DEBUG,"extract_subkey with neither INNER or OUTER");
+	retval = NULL;
+    }
+    return(retval);
+}
+
+/*    
+ * samekeys--
+ *    Returns t iff two sets of path keys are equivalent.  They are 
+ *    equivalent if the first subkey (var node) within each sublist of 
+ *    list 'keys1' is contained within the corresponding sublist of 'keys2'.
+ *    
+ *    XXX 	It isn't necessary to check that each sublist exactly contain 
+ *    		the same elements because if the routine that built these
+ *    		sublists together is correct, having one element in common 
+ *    		implies having all elements in common.
+ *    
+ */
+bool
+samekeys(List *keys1, List *keys2)
+{
+    bool allmember = true;
+    List *key1, *key2;
+
+    for(key1=keys1,key2=keys2 ; key1 != NIL && key2 !=NIL ; 
+	key1=lnext(key1), key2=lnext(key2)) 
+	if (!member(lfirst(key1), lfirst(key2)))
+	    allmember = false;
+
+    if ( (length (keys2) >= length (keys1)) && allmember)
+	return(true);
+    else
+	return(false);
+}
+
+/*    
+ * collect-index-pathkeys--
+ *    Creates a list of subkeys by retrieving var nodes corresponding to
+ *    each index key in 'index-keys' from the relation's target list
+ *    'tlist'.  If the key is not in the target list, the key is irrelevant
+ *    and is thrown away.  The returned subkey list is of the form:
+ *    		((var1) (var2) ... (varn))
+ *    
+ * 'index-keys' is a list of index keys
+ * 'tlist' is a relation target list
+ *    
+ * Returns the list of cons'd subkeys.
+ *    
+ */
+/* This function is identical to matching_tlvar and tlistentry_member.
+ * They should be merged.
+ */
+static Expr *
+matching2_tlvar(int var, List *tlist, bool (*test)())
+{
+    TargetEntry *tlentry = NULL;
+
+    if (var) {
+	List *temp;
+	foreach (temp,tlist) {
+	    if ((*test)(var, get_expr(lfirst(temp)))) {
+		tlentry = lfirst(temp);
+		break;
+	    }
+	}
+    }
+
+    if (tlentry) 
+	return((Expr*)get_expr(tlentry));
+    else
+	return((Expr*)NULL);
+}
+
+
+List *
+collect_index_pathkeys(int *index_keys, List *tlist)
+{
+    List *retval = NIL;
+
+    Assert (index_keys != NULL);
+
+    while(index_keys[0] != 0) {
+	Expr *mvar;
+	mvar = matching2_tlvar(index_keys[0],
+			       tlist,
+			       equal_indexkey_var);
+	if (mvar) 
+	    retval = nconc(retval,lcons(lcons(mvar,NIL),
+					NIL));
+	index_keys++;
+    }
+    return(retval);
+}
+