Postgres95 1.01 Distribution - Virgin Sources

src/backend/access/nbtree/nbtutils.c

@@ -0,0 +1,239 @@
+/*-------------------------------------------------------------------------
+ *
+ * btutils.c--
+ *    Utility code for Postgres btree implementation.
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *    $Header: /cvsroot/pgsql/src/backend/access/nbtree/nbtutils.c,v 1.1.1.1 1996/07/09 06:21:12 scrappy Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#include <stdio.h>
+#include "postgres.h"
+
+#include "storage/bufmgr.h"
+#include "storage/bufpage.h"
+
+#include "fmgr.h"
+#include "utils/elog.h"
+#include "utils/palloc.h"
+#include "utils/rel.h"
+#include "utils/excid.h"
+#include "utils/datum.h"
+
+#include "access/heapam.h"
+#include "access/genam.h"
+#include "access/iqual.h"
+#include "access/nbtree.h"
+
+ScanKey 
+_bt_mkscankey(Relation rel, IndexTuple itup)
+{     
+    ScanKey skey;
+    TupleDesc itupdesc;
+    int natts;
+    int i;
+    Datum arg;
+    RegProcedure proc;
+    bool null;
+    
+    natts = rel->rd_rel->relnatts;
+    itupdesc = RelationGetTupleDescriptor(rel);
+    
+    skey = (ScanKey) palloc(natts * sizeof(ScanKeyData));
+    
+    for (i = 0; i < natts; i++) {
+	arg = index_getattr(itup, i + 1, itupdesc, &null);
+	proc = index_getprocid(rel, i + 1, BTORDER_PROC);
+	ScanKeyEntryInitialize(&skey[i],
+			       0x0, (AttrNumber) (i + 1), proc, arg);
+    }
+    
+    return (skey);
+}
+
+void
+_bt_freeskey(ScanKey skey)
+{
+    pfree(skey);
+}
+
+void
+_bt_freestack(BTStack stack)
+{
+    BTStack ostack;
+    
+    while (stack != (BTStack) NULL) {
+	ostack = stack;
+	stack = stack->bts_parent;
+	pfree(ostack->bts_btitem);
+	pfree(ostack);
+    }
+}
+
+/*
+ *  _bt_orderkeys() -- Put keys in a sensible order for conjunctive quals.
+ *
+ *	The order of the keys in the qual match the ordering imposed by
+ *	the index.  This routine only needs to be called if there are
+ *	more than one qual clauses using this index.
+ */
+void
+_bt_orderkeys(Relation relation, uint16 *numberOfKeys, ScanKey key)
+{
+    ScanKey xform;
+    ScanKeyData *cur;
+    StrategyMap map;
+    int nbytes;
+    long test;
+    int i, j;
+    int init[BTMaxStrategyNumber+1];
+    
+    /* haven't looked at any strategies yet */
+    for (i = 0; i <= BTMaxStrategyNumber; i++)
+	init[i] = 0;
+    
+    /* get space for the modified array of keys */
+    nbytes = BTMaxStrategyNumber * sizeof(ScanKeyData);
+    xform = (ScanKey) palloc(nbytes);
+    memset(xform, 0, nbytes); 
+    
+    
+    /* get the strategy map for this index/attribute pair */
+    /*
+     *  XXX
+     *  When we support multiple keys in a single index, this is what
+     *  we'll want to do.  At present, the planner is hosed, so we
+     *  hard-wire the attribute number below.  Postgres only does single-
+     *  key indices...
+     * map = IndexStrategyGetStrategyMap(RelationGetIndexStrategy(relation),
+     * 				    BTMaxStrategyNumber,
+     * 				    key->data[0].attributeNumber);
+     */
+    map = IndexStrategyGetStrategyMap(RelationGetIndexStrategy(relation),
+				      BTMaxStrategyNumber,
+				      1 /* XXX */ );
+    
+    /* check each key passed in */
+    for (i = *numberOfKeys; --i >= 0; ) {
+	cur = &key[i];
+	for (j = BTMaxStrategyNumber; --j >= 0; ) {
+	    if (cur->sk_procedure == map->entry[j].sk_procedure)
+		break;
+	}
+	
+	/* have we seen one of these before? */
+	if (init[j]) {
+	    /* yup, use the appropriate value */
+	    test =
+		(long) FMGR_PTR2(cur->sk_func, cur->sk_procedure,
+				 cur->sk_argument, xform[j].sk_argument);
+	    if (test)
+		xform[j].sk_argument = cur->sk_argument;
+	} else {
+	    /* nope, use this value */
+	    memmove(&xform[j], cur, sizeof(*cur));
+	   
+	    init[j] = 1;
+	}
+    }
+    
+    /* if = has been specified, no other key will be used */
+    if (init[BTEqualStrategyNumber - 1]) {
+	init[BTLessStrategyNumber - 1] = 0;
+	init[BTLessEqualStrategyNumber - 1] = 0;
+	init[BTGreaterEqualStrategyNumber - 1] = 0;
+	init[BTGreaterStrategyNumber - 1] = 0;
+    }
+    
+    /* only one of <, <= */
+    if (init[BTLessStrategyNumber - 1]
+	&& init[BTLessEqualStrategyNumber - 1]) {
+	
+	ScanKeyData *lt, *le;
+	
+	lt = &xform[BTLessStrategyNumber - 1];
+	le = &xform[BTLessEqualStrategyNumber - 1];
+	
+	/*
+	 *  DO NOT use the cached function stuff here -- this is key
+	 *  ordering, happens only when the user expresses a hokey
+	 *  qualification, and gets executed only once, anyway.  The
+	 *  transform maps are hard-coded, and can't be initialized
+	 *  in the correct way.
+	 */
+	
+	test = (long) fmgr(le->sk_procedure, le->sk_argument, lt->sk_argument);
+	
+	if (test)
+	    init[BTLessEqualStrategyNumber - 1] = 0;
+	else
+	    init[BTLessStrategyNumber - 1] = 0;
+    }
+    
+    /* only one of >, >= */
+    if (init[BTGreaterStrategyNumber - 1]
+	&& init[BTGreaterEqualStrategyNumber - 1]) {
+	
+	ScanKeyData *gt, *ge;
+	
+	gt = &xform[BTGreaterStrategyNumber - 1];
+	ge = &xform[BTGreaterEqualStrategyNumber - 1];
+	
+	/* see note above on function cache */
+	test = (long) fmgr(ge->sk_procedure, gt->sk_argument, gt->sk_argument);
+	
+	if (test)
+	    init[BTGreaterStrategyNumber - 1] = 0;
+	else
+	    init[BTGreaterEqualStrategyNumber - 1] = 0;
+    }
+    
+    /* okay, reorder and count */
+    j = 0;
+    
+    for (i = BTMaxStrategyNumber; --i >= 0; )
+	if (init[i])
+	    key[j++] = xform[i];
+    
+    *numberOfKeys = j;
+    
+    pfree(xform);
+}
+
+bool
+_bt_checkqual(IndexScanDesc scan, IndexTuple itup)
+{
+    if (scan->numberOfKeys > 0)
+	return (index_keytest(itup, RelationGetTupleDescriptor(scan->relation),
+			      scan->numberOfKeys, scan->keyData));
+    else
+	return (true);
+}
+
+BTItem
+_bt_formitem(IndexTuple itup)
+{
+    int nbytes_btitem;
+    BTItem btitem;
+    Size tuplen;
+    extern Oid newoid();
+    
+    /* disallow nulls in btree keys */
+    if (itup->t_info & INDEX_NULL_MASK)
+	elog(WARN, "btree indices cannot include null keys");
+    
+    /* make a copy of the index tuple with room for the sequence number */
+    tuplen = IndexTupleSize(itup);
+    nbytes_btitem = tuplen +
+	(sizeof(BTItemData) - sizeof(IndexTupleData));
+    
+    btitem = (BTItem) palloc(nbytes_btitem);
+    memmove((char *) &(btitem->bti_itup), (char *) itup, tuplen);
+    
+    btitem->bti_oid = newoid();
+    return (btitem);
+}