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69c7f25bed
I found another bug in btree index. Looking at the code it seems that NULL
keys are never used to build or scan a btree index (see the explain commands
in the example). However this is not the case when a null key is retrieved
in an outer loop of a join select and used in an index scan of an inner loop.
This bug causes at least three kinds of problems:
1) the backend crashes when it tries to compare a text string with a null.
2) it is not possible to find tuples with null keys in a join.
3) null is considered equal to 0 when the datum is passed by value, see
the last query.
Submitted by: Massimo Dal Zotto <dz@cs.unitn.it>
156 lines
3.8 KiB
C
156 lines
3.8 KiB
C
/*-------------------------------------------------------------------------
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*
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* heapvalid.c--
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* heap tuple qualification validity checking code
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*
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* Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/access/common/Attic/heapvalid.c,v 1.7 1996/10/30 06:07:56 scrappy Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#include <time.h>
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#include "postgres.h"
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#include "fmgr.h"
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#include "access/attnum.h"
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#include "catalog/pg_am.h"
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#include "catalog/pg_attribute.h"
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#include "catalog/pg_class.h"
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#include "nodes/nodes.h"
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#include "nodes/pg_list.h"
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#include "storage/block.h"
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#include "storage/buf.h"
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#include "storage/fd.h"
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#include "storage/item.h"
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#include "storage/itemid.h"
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#include "storage/off.h"
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#include "utils/nabstime.h"
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#include "access/skey.h"
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#include "access/tupdesc.h"
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#include "access/xact.h"
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#include "rewrite/prs2lock.h"
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#include "storage/bufpage.h"
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#include "storage/itemptr.h"
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#include "access/strat.h"
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#include "access/htup.h"
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#include "utils/rel.h"
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#include "access/heaptuple.h"
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#include "utils/tqual.h"
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/* ----------------
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* heap_keytest
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*
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* Test a heap tuple with respect to a scan key.
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* ----------------
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*/
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bool
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heap_keytest(HeapTuple t,
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TupleDesc tupdesc,
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int nkeys,
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ScanKey keys)
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{
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bool isnull;
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Datum atp;
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int test;
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for (; nkeys--; keys++) {
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atp = (Datum)heap_getattr(t, InvalidBuffer,
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keys->sk_attno,
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tupdesc,
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&isnull);
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if (isnull)
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/* XXX eventually should check if SK_ISNULL */
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return false;
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if (keys->sk_flags & SK_ISNULL) {
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return (false);
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}
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if (keys->sk_flags & SK_COMMUTE)
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test = (long) FMGR_PTR2(keys->sk_func, keys->sk_procedure,
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keys->sk_argument, atp);
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else
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test = (long) FMGR_PTR2(keys->sk_func, keys->sk_procedure,
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atp, keys->sk_argument);
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if (!test == !(keys->sk_flags & SK_NEGATE))
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return false;
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}
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return true;
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}
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/* ----------------
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* heap_tuple_satisfies
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*
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* Returns a valid HeapTuple if it satisfies the timequal and keytest.
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* Returns NULL otherwise. Used to be heap_satisifies (sic) which
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* returned a boolean. It now returns a tuple so that we can avoid doing two
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* PageGetItem's per tuple.
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*
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* Complete check of validity including LP_CTUP and keytest.
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* This should perhaps be combined with valid somehow in the
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* future. (Also, additional rule tests/time range tests.)
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*
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* on 8/21/92 mao says: i rearranged the tests here to do keytest before
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* SatisfiesTimeQual. profiling indicated that even for vacuumed relations,
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* time qual checking was more expensive than key testing. time qual is
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* least likely to fail, too. we should really add the time qual test to
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* the restriction and optimize it in the normal way. this has interactions
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* with joey's expensive function work.
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* ----------------
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*/
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HeapTuple
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heap_tuple_satisfies(ItemId itemId,
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Relation relation,
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PageHeader disk_page,
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TimeQual qual,
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int nKeys,
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ScanKey key)
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{
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HeapTuple tuple;
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bool res;
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if (! ItemIdIsUsed(itemId))
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return NULL;
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tuple = (HeapTuple) PageGetItem((Page) disk_page, itemId);
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if (key != NULL)
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res = heap_keytest(tuple, RelationGetTupleDescriptor(relation),
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nKeys, key);
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else
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res = TRUE;
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if (res && (relation->rd_rel->relkind == RELKIND_UNCATALOGED
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|| HeapTupleSatisfiesTimeQual(tuple,qual)))
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return tuple;
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return (HeapTuple) NULL;
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}
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/*
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* TupleUpdatedByCurXactAndCmd() -- Returns true if this tuple has
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* already been updated once by the current transaction/command
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* pair.
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*/
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bool
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TupleUpdatedByCurXactAndCmd(HeapTuple t)
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{
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if (TransactionIdEquals(t->t_xmax,
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GetCurrentTransactionId()) &&
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t->t_cmax == GetCurrentCommandId())
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return true;
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return false;
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}
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