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Back-patch fixes for problems with VACUUM destroying t_ctid chains too soon,

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and with insufficient paranoia in code that follows t_ctid links.
This patch covers the 7.3 branch.
This commit is contained in:
Tom Lane 2005-08-26 20:07:17 +00:00
parent d5bd53c2c5
commit 26f1202ca3
7 changed files with 385 additions and 196 deletions
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243
src/backend/access/heap/heapam.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/access/heap/heapam.c,v 1.149.2.1 2004/10/13 22:22:21 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/access/heap/heapam.c,v 1.149.2.2 2005/08/26 20:07:15 tgl Exp $
*
*
* INTERFACE ROUTINES
@ -1014,89 +1014,136 @@ heap_fetch(Relation relation,
/*
* heap_get_latest_tid - get the latest tid of a specified tuple
*
* Actually, this gets the latest version that is visible according to
* the passed snapshot. You can pass SnapshotDirty to get the very latest,
* possibly uncommitted version.
*
* *tid is both an input and an output parameter: it is updated to
* show the latest version of the row. Note that it will not be changed
* if no version of the row passes the snapshot test.
*/
ItemPointer
void
heap_get_latest_tid(Relation relation,
Snapshot snapshot,
ItemPointer tid)
{
ItemId lp = NULL;
Buffer buffer;
PageHeader dp;
OffsetNumber offnum;
HeapTupleData tp;
HeapTupleHeader t_data;
BlockNumber blk;
ItemPointerData ctid;
bool invalidBlock,
linkend,
valid;
TransactionId priorXmax;
/* this is to avoid Assert failures on bad input */
if (!ItemPointerIsValid(tid))
return;
/*
* get the buffer from the relation descriptor Note that this does a
* buffer pin.
* Since this can be called with user-supplied TID, don't trust the
* input too much. (RelationGetNumberOfBlocks is an expensive check,
* so we don't check t_ctid links again this way. Note that it would
* not do to call it just once and save the result, either.)
*/
buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(tid));
if (!BufferIsValid(buffer))
elog(ERROR, "heap_get_latest_tid: %s relation: ReadBuffer(%lx) failed",
RelationGetRelationName(relation), (long) tid);
LockBuffer(buffer, BUFFER_LOCK_SHARE);
blk = ItemPointerGetBlockNumber(tid);
if (blk >= RelationGetNumberOfBlocks(relation))
elog(ERROR, "block number %u is out of range for relation \"%s\"",
blk, RelationGetRelationName(relation));
/*
* get the item line pointer corresponding to the requested tid
* Loop to chase down t_ctid links. At top of loop, ctid is the
* tuple we need to examine, and *tid is the TID we will return if
* ctid turns out to be bogus.
*
* Note that we will loop until we reach the end of the t_ctid chain.
* Depending on the snapshot passed, there might be at most one visible
* version of the row, but we don't try to optimize for that.
*/
dp = (PageHeader) BufferGetPage(buffer);
offnum = ItemPointerGetOffsetNumber(tid);
invalidBlock = true;
if (!PageIsNew(dp))
ctid = *tid;
priorXmax = InvalidTransactionId; /* cannot check first XMIN */
for (;;)
{
Buffer buffer;
PageHeader dp;
OffsetNumber offnum;
ItemId lp;
HeapTupleData tp;
bool valid;
/*
* Read, pin, and lock the page.
*/
buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(&ctid));
if (!BufferIsValid(buffer))
elog(ERROR, "ReadBuffer(\"%s\", %lu) failed",
RelationGetRelationName(relation),
(unsigned long) ItemPointerGetBlockNumber(&ctid));
LockBuffer(buffer, BUFFER_LOCK_SHARE);
dp = (PageHeader) BufferGetPage(buffer);
/*
* Check for bogus item number. This is not treated as an error
* condition because it can happen while following a t_ctid link.
* We just assume that the prior tid is OK and return it unchanged.
*/
offnum = ItemPointerGetOffsetNumber(&ctid);
if (offnum < FirstOffsetNumber || offnum > PageGetMaxOffsetNumber(dp))
{
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
ReleaseBuffer(buffer);
break;
}
lp = PageGetItemId(dp, offnum);
if (ItemIdIsUsed(lp))
invalidBlock = false;
}
if (invalidBlock)
{
if (!ItemIdIsUsed(lp))
{
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
ReleaseBuffer(buffer);
break;
}
/* OK to access the tuple */
tp.t_self = ctid;
tp.t_datamcxt = NULL;
tp.t_data = (HeapTupleHeader) PageGetItem(dp, lp);
tp.t_len = ItemIdGetLength(lp);
/*
* After following a t_ctid link, we might arrive at an unrelated
* tuple. Check for XMIN match.
*/
if (TransactionIdIsValid(priorXmax) &&
!TransactionIdEquals(priorXmax, HeapTupleHeaderGetXmin(tp.t_data)))
{
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
ReleaseBuffer(buffer);
break;
}
/*
* Check time qualification of tuple; if visible, set it as the new
* result candidate.
*/
HeapTupleSatisfies(&tp, relation, buffer, dp,
snapshot, 0, NULL, valid);
if (valid)
*tid = ctid;
/*
* If there's a valid t_ctid link, follow it, else we're done.
*/
if ((tp.t_data->t_infomask & (HEAP_XMAX_INVALID |
HEAP_MARKED_FOR_UPDATE)) ||
ItemPointerEquals(&tp.t_self, &tp.t_data->t_ctid))
{
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
ReleaseBuffer(buffer);
break;
}
ctid = tp.t_data->t_ctid;
priorXmax = HeapTupleHeaderGetXmax(tp.t_data);
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
ReleaseBuffer(buffer);
return NULL;
}
/*
* more sanity checks
*/
tp.t_datamcxt = NULL;
t_data = tp.t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp);
tp.t_len = ItemIdGetLength(lp);
tp.t_self = *tid;
ctid = tp.t_data->t_ctid;
/*
* check time qualification of tid
*/
HeapTupleSatisfies(&tp, relation, buffer, dp,
snapshot, 0, (ScanKey) NULL, valid);
linkend = true;
if ((t_data->t_infomask & HEAP_XMIN_COMMITTED) != 0 &&
!ItemPointerEquals(tid, &ctid))
linkend = false;
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
ReleaseBuffer(buffer);
if (!valid)
{
if (linkend)
return NULL;
heap_get_latest_tid(relation, snapshot, &ctid);
*tid = ctid;
}
return tid;
} /* end of loop */
}
/*
@ -1264,7 +1311,8 @@ simple_heap_insert(Relation relation, HeapTuple tup)
*/
int
heap_delete(Relation relation, ItemPointer tid,
ItemPointer ctid, CommandId cid)
ItemPointer ctid, TransactionId *update_xmax,
CommandId cid)
{
ItemId lp;
HeapTupleData tp;
@ -1288,11 +1336,11 @@ heap_delete(Relation relation, ItemPointer tid,
dp = (PageHeader) BufferGetPage(buffer);
lp = PageGetItemId(dp, ItemPointerGetOffsetNumber(tid));
tp.t_datamcxt = NULL;
tp.t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp);
tp.t_data = (HeapTupleHeader) PageGetItem(dp, lp);
tp.t_len = ItemIdGetLength(lp);
tp.t_self = *tid;
tp.t_tableOid = relation->rd_id;
l1:
sv_infomask = tp.t_data->t_infomask;
@ -1339,7 +1387,9 @@ l1:
if (result != HeapTupleMayBeUpdated)
{
Assert(result == HeapTupleSelfUpdated || result == HeapTupleUpdated);
Assert(!(tp.t_data->t_infomask & HEAP_XMAX_INVALID));
*ctid = tp.t_data->t_ctid;
*update_xmax = HeapTupleHeaderGetXmax(tp.t_data);
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
ReleaseBuffer(buffer);
return result;
@ -1429,10 +1479,13 @@ l1:
void
simple_heap_delete(Relation relation, ItemPointer tid)
{
ItemPointerData ctid;
int result;
ItemPointerData update_ctid;
TransactionId update_xmax;
result = heap_delete(relation, tid, &ctid, GetCurrentCommandId());
result = heap_delete(relation, tid,
&update_ctid, &update_xmax,
GetCurrentCommandId());
switch (result)
{
case HeapTupleSelfUpdated:
@ -1462,7 +1515,8 @@ simple_heap_delete(Relation relation, ItemPointer tid)
*/
int
heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
ItemPointer ctid, CommandId cid)
ItemPointer ctid, TransactionId *update_xmax,
CommandId cid)
{
ItemId lp;
HeapTupleData oldtup;
@ -1547,7 +1601,9 @@ l2:
if (result != HeapTupleMayBeUpdated)
{
Assert(result == HeapTupleSelfUpdated || result == HeapTupleUpdated);
Assert(!(oldtup.t_data->t_infomask & HEAP_XMAX_INVALID));
*ctid = oldtup.t_data->t_ctid;
*update_xmax = HeapTupleHeaderGetXmax(oldtup.t_data);
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
ReleaseBuffer(buffer);
return result;
@ -1767,10 +1823,13 @@ l2:
void
simple_heap_update(Relation relation, ItemPointer otid, HeapTuple tup)
{
ItemPointerData ctid;
int result;
ItemPointerData update_ctid;
TransactionId update_xmax;
result = heap_update(relation, otid, tup, &ctid, GetCurrentCommandId());
result = heap_update(relation, otid, tup,
&update_ctid, &update_xmax,
GetCurrentCommandId());
switch (result)
{
case HeapTupleSelfUpdated:
@ -1794,9 +1853,34 @@ simple_heap_update(Relation relation, ItemPointer otid, HeapTuple tup)
/*
* heap_mark4update - mark a tuple for update
*
* Note that this acquires a buffer pin, which the caller must release.
*
* Input parameters:
* relation: relation containing tuple (caller must hold suitable lock)
* tuple->t_self: TID of tuple to lock (rest of struct need not be valid)
* cid: current command ID (used for visibility test, and stored into
* tuple's cmax if lock is successful)
*
* Output parameters:
* *tuple: all fields filled in
* *buffer: set to buffer holding tuple (pinned but not locked at exit)
* *ctid: set to tuple's t_ctid, but only in failure cases
* *update_xmax: set to tuple's xmax, but only in failure cases
*
* Function result may be:
* HeapTupleMayBeUpdated: lock was successfully acquired
* HeapTupleSelfUpdated: lock failed because tuple updated by self
* HeapTupleUpdated: lock failed because tuple updated by other xact
*
* In the failure cases, the routine returns the tuple's t_ctid and t_xmax.
* If t_ctid is the same as t_self, the tuple was deleted; if different, the
* tuple was updated, and t_ctid is the location of the replacement tuple.
* (t_xmax is needed to verify that the replacement tuple matches.)
*/
int
heap_mark4update(Relation relation, HeapTuple tuple, Buffer *buffer,
ItemPointer ctid, TransactionId *update_xmax,
CommandId cid)
{
ItemPointer tid = &(tuple->t_self);
@ -1818,9 +1902,12 @@ heap_mark4update(Relation relation, HeapTuple tuple, Buffer *buffer,
dp = (PageHeader) BufferGetPage(*buffer);
lp = PageGetItemId(dp, ItemPointerGetOffsetNumber(tid));
Assert(ItemIdIsUsed(lp));
tuple->t_datamcxt = NULL;
tuple->t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp);
tuple->t_len = ItemIdGetLength(lp);
tuple->t_tableOid = RelationGetRelid(relation);
l3:
sv_infomask = tuple->t_data->t_infomask;
@ -1867,7 +1954,9 @@ l3:
if (result != HeapTupleMayBeUpdated)
{
Assert(result == HeapTupleSelfUpdated || result == HeapTupleUpdated);
tuple->t_self = tuple->t_data->t_ctid;
Assert(!(tuple->t_data->t_infomask & HEAP_XMAX_INVALID));
*ctid = tuple->t_data->t_ctid;
*update_xmax = HeapTupleHeaderGetXmax(tuple->t_data);
LockBuffer(*buffer, BUFFER_LOCK_UNLOCK);
return result;
}

28
src/backend/commands/trigger.c
View File

@ -7,7 +7,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/commands/trigger.c,v 1.136.2.2 2003/05/19 17:23:54 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/commands/trigger.c,v 1.136.2.3 2005/08/26 20:07:15 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1351,14 +1351,18 @@ GetTupleForTrigger(EState *estate, ResultRelInfo *relinfo,
if (newSlot != NULL)
{
int test;
ItemPointerData update_ctid;
TransactionId update_xmax;
*newSlot = NULL;
/*
* mark tuple for update
*/
*newSlot = NULL;
tuple.t_self = *tid;
ltrmark:;
test = heap_mark4update(relation, &tuple, &buffer, cid);
tuple.t_self = *tid;
test = heap_mark4update(relation, &tuple, &buffer,
&update_ctid, &update_xmax, cid);
switch (test)
{
case HeapTupleSelfUpdated:
@ -1373,15 +1377,18 @@ ltrmark:;
ReleaseBuffer(buffer);
if (XactIsoLevel == XACT_SERIALIZABLE)
elog(ERROR, "Can't serialize access due to concurrent update");
else if (!(ItemPointerEquals(&(tuple.t_self), tid)))
else if (!ItemPointerEquals(&update_ctid, &tuple.t_self))
{
TupleTableSlot *epqslot = EvalPlanQual(estate,
relinfo->ri_RangeTableIndex,
&(tuple.t_self));
/* it was updated, so look at the updated version */
TupleTableSlot *epqslot;
if (!(TupIsNull(epqslot)))
epqslot = EvalPlanQual(estate,
relinfo->ri_RangeTableIndex,
&update_ctid,
update_xmax);
if (!TupIsNull(epqslot))
{
*tid = tuple.t_self;
*tid = update_ctid;
*newSlot = epqslot;
goto ltrmark;
}
@ -1418,6 +1425,7 @@ ltrmark:;
tuple.t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp);
tuple.t_len = ItemIdGetLength(lp);
tuple.t_self = *tid;
tuple.t_tableOid = RelationGetRelid(relation);
}
result = heap_copytuple(&tuple);

138
src/backend/commands/vacuum.c
View File

@ -13,7 +13,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.244 2002/10/31 19:25:29 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/commands/vacuum.c,v 1.244.2.1 2005/08/26 20:07:16 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1646,8 +1646,6 @@ repair_frag(VRelStats *vacrelstats, Relation onerel,
Buffer Cbuf = buf;
bool freeCbuf = false;
bool chain_move_failed = false;
Page Cpage;
ItemId Citemid;
ItemPointerData Ctid;
HeapTupleData tp = tuple;
Size tlen = tuple_len;
@ -1671,68 +1669,85 @@ repair_frag(VRelStats *vacrelstats, Relation onerel,
break; /* out of walk-along-page loop */
}
vtmove = (VTupleMove) palloc(100 * sizeof(VTupleMoveData));
num_vtmove = 0;
free_vtmove = 100;
/*
* If this tuple is in the begin/middle of the chain then
* we have to move to the end of chain.
* we have to move to the end of chain. As with any
* t_ctid chase, we have to verify that each new tuple
* is really the descendant of the tuple we came from.
*/
while (!(tp.t_data->t_infomask & (HEAP_XMAX_INVALID |
HEAP_MARKED_FOR_UPDATE)) &&
!(ItemPointerEquals(&(tp.t_self),
&(tp.t_data->t_ctid))))
{
Ctid = tp.t_data->t_ctid;
if (freeCbuf)
ReleaseBuffer(Cbuf);
freeCbuf = true;
Cbuf = ReadBuffer(onerel,
ItemPointerGetBlockNumber(&Ctid));
Cpage = BufferGetPage(Cbuf);
Citemid = PageGetItemId(Cpage,
ItemPointerGetOffsetNumber(&Ctid));
if (!ItemIdIsUsed(Citemid))
ItemPointerData nextTid;
TransactionId priorXmax;
Buffer nextBuf;
Page nextPage;
OffsetNumber nextOffnum;
ItemId nextItemid;
HeapTupleHeader nextTdata;
nextTid = tp.t_data->t_ctid;
priorXmax = HeapTupleHeaderGetXmax(tp.t_data);
/* assume block# is OK (see heap_fetch comments) */
nextBuf = ReadBuffer(onerel,
ItemPointerGetBlockNumber(&nextTid));
nextPage = BufferGetPage(nextBuf);
/* If bogus or unused slot, assume tp is end of chain */
nextOffnum = ItemPointerGetOffsetNumber(&nextTid);
if (nextOffnum < FirstOffsetNumber ||
nextOffnum > PageGetMaxOffsetNumber(nextPage))
{
/*
* This means that in the middle of chain there
* was tuple updated by older (than OldestXmin)
* xaction and this tuple is already deleted by
* me. Actually, upper part of chain should be
* removed and seems that this should be handled
* in scan_heap(), but it's not implemented at the
* moment and so we just stop shrinking here.
*/
elog(DEBUG1, "Child itemid in update-chain marked as unused - can't continue repair_frag");
chain_move_failed = true;
break; /* out of loop to move to chain end */
ReleaseBuffer(nextBuf);
break;
}
nextItemid = PageGetItemId(nextPage, nextOffnum);
if (!ItemIdIsUsed(nextItemid))
{
ReleaseBuffer(nextBuf);
break;
}
/* if not matching XMIN, assume tp is end of chain */
nextTdata = (HeapTupleHeader) PageGetItem(nextPage,
nextItemid);
if (!TransactionIdEquals(HeapTupleHeaderGetXmin(nextTdata),
priorXmax))
{
ReleaseBuffer(nextBuf);
break;
}
/* OK, switch our attention to the next tuple in chain */
tp.t_datamcxt = NULL;
tp.t_data = (HeapTupleHeader) PageGetItem(Cpage, Citemid);
tp.t_self = Ctid;
tlen = tp.t_len = ItemIdGetLength(Citemid);
}
if (chain_move_failed)
{
tp.t_data = nextTdata;
tp.t_self = nextTid;
tlen = tp.t_len = ItemIdGetLength(nextItemid);
if (freeCbuf)
ReleaseBuffer(Cbuf);
pfree(vtmove);
break; /* out of walk-along-page loop */
Cbuf = nextBuf;
freeCbuf = true;
}
/* Set up workspace for planning the chain move */
vtmove = (VTupleMove) palloc(100 * sizeof(VTupleMoveData));
num_vtmove = 0;
free_vtmove = 100;
/*
* Check if all items in chain can be moved
* Now, walk backwards up the chain (towards older tuples)
* and check if all items in chain can be moved. We record
* all the moves that need to be made in the vtmove array.
*/
for (;;)
{
Buffer Pbuf;
Page Ppage;
ItemId Pitemid;
HeapTupleData Ptp;
HeapTupleHeader PTdata;
VTupleLinkData vtld,
*vtlp;
/* Identify a target page to move this tuple to */
if (to_vacpage == NULL ||
!enough_space(to_vacpage, tlen))
{
@ -1802,18 +1817,17 @@ repair_frag(VRelStats *vacrelstats, Relation onerel,
/* this can't happen since we saw tuple earlier: */
if (!ItemIdIsUsed(Pitemid))
elog(ERROR, "Parent itemid marked as unused");
Ptp.t_datamcxt = NULL;
Ptp.t_data = (HeapTupleHeader) PageGetItem(Ppage, Pitemid);
PTdata = (HeapTupleHeader) PageGetItem(Ppage, Pitemid);
/* ctid should not have changed since we saved it */
Assert(ItemPointerEquals(&(vtld.new_tid),
&(Ptp.t_data->t_ctid)));
&(PTdata->t_ctid)));
/*
* Read above about cases when !ItemIdIsUsed(Citemid)
* Read above about cases when !ItemIdIsUsed(nextItemid)
* (child item is removed)... Due to the fact that at
* the moment we don't remove unuseful part of
* update-chain, it's possible to get too old parent
* update-chain, it's possible to get non-matching parent
* row here. Like as in the case which caused this
* problem, we stop shrinking here. I could try to
* find real parent row but want not to do it because
@ -1821,7 +1835,7 @@ repair_frag(VRelStats *vacrelstats, Relation onerel,
* and we are too close to 6.5 release. - vadim
* 06/11/99
*/
if (!(TransactionIdEquals(HeapTupleHeaderGetXmax(Ptp.t_data),
if (!(TransactionIdEquals(HeapTupleHeaderGetXmax(PTdata),
HeapTupleHeaderGetXmin(tp.t_data))))
{
ReleaseBuffer(Pbuf);
@ -1829,8 +1843,8 @@ repair_frag(VRelStats *vacrelstats, Relation onerel,
chain_move_failed = true;
break; /* out of check-all-items loop */
}
tp.t_datamcxt = Ptp.t_datamcxt;
tp.t_data = Ptp.t_data;
tp.t_datamcxt = NULL;
tp.t_data = PTdata;
tlen = tp.t_len = ItemIdGetLength(Pitemid);
if (freeCbuf)
ReleaseBuffer(Cbuf);
@ -1865,6 +1879,8 @@ repair_frag(VRelStats *vacrelstats, Relation onerel,
for (ti = 0; ti < num_vtmove; ti++)
{
VacPage destvacpage = vtmove[ti].vacpage;
Page Cpage;
ItemId Citemid;
/* Get page to move from */
tuple.t_self = vtmove[ti].tid;
@ -1953,16 +1969,27 @@ repair_frag(VRelStats *vacrelstats, Relation onerel,
InvalidOffsetNumber,
LP_USED);
if (newoff == InvalidOffsetNumber)
{
elog(PANIC, "moving chain: failed to add item with len = %lu to page %u",
(unsigned long) tuple_len, destvacpage->blkno);
}
newitemid = PageGetItemId(ToPage, newoff);
/* drop temporary copy, and point to the version on the dest page */
pfree(newtup.t_data);
newtup.t_datamcxt = NULL;
newtup.t_data = (HeapTupleHeader) PageGetItem(ToPage, newitemid);
ItemPointerSet(&(newtup.t_self), destvacpage->blkno, newoff);
/*
* Set new tuple's t_ctid pointing to itself for last
* tuple in chain, and to next tuple in chain
* otherwise.
*/
if (!ItemPointerIsValid(&Ctid))
newtup.t_data->t_ctid = newtup.t_self;
else
newtup.t_data->t_ctid = Ctid;
Ctid = newtup.t_self;
/* XLOG stuff */
if (!onerel->rd_istemp)
{
@ -1992,17 +2019,6 @@ repair_frag(VRelStats *vacrelstats, Relation onerel,
if (destvacpage->blkno > last_move_dest_block)
last_move_dest_block = destvacpage->blkno;
/*
* Set new tuple's t_ctid pointing to itself for last
* tuple in chain, and to next tuple in chain
* otherwise.
*/
if (!ItemPointerIsValid(&Ctid))
newtup.t_data->t_ctid = newtup.t_self;
else
newtup.t_data->t_ctid = Ctid;
Ctid = newtup.t_self;
num_moved++;
/*

137
src/backend/executor/execMain.c
View File

@ -27,7 +27,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/executor/execMain.c,v 1.180.2.2 2003/03/27 14:33:21 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/executor/execMain.c,v 1.180.2.3 2005/08/26 20:07:17 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1012,8 +1012,10 @@ lnext: ;
foreach(l, estate->es_rowMark)
{
execRowMark *erm = lfirst(l);
Buffer buffer;
HeapTupleData tuple;
Buffer buffer;
ItemPointerData update_ctid;
TransactionId update_xmax;
TupleTableSlot *newSlot;
int test;
@ -1032,6 +1034,7 @@ lnext: ;
tuple.t_self = *((ItemPointer) DatumGetPointer(datum));
test = heap_mark4update(erm->relation, &tuple, &buffer,
&update_ctid, &update_xmax,
estate->es_snapshot->curcid);
ReleaseBuffer(buffer);
switch (test)
@ -1046,11 +1049,15 @@ lnext: ;
case HeapTupleUpdated:
if (XactIsoLevel == XACT_SERIALIZABLE)
elog(ERROR, "Can't serialize access due to concurrent update");
if (!(ItemPointerEquals(&(tuple.t_self),
(ItemPointer) DatumGetPointer(datum))))
if (!ItemPointerEquals(&update_ctid,
&tuple.t_self))
{
newSlot = EvalPlanQual(estate, erm->rti, &(tuple.t_self));
if (!(TupIsNull(newSlot)))
/* updated, so look at updated version */
newSlot = EvalPlanQual(estate,
erm->rti,
&update_ctid,
update_xmax);
if (!TupIsNull(newSlot))
{
slot = newSlot;
estate->es_useEvalPlan = true;
@ -1280,8 +1287,9 @@ ExecDelete(TupleTableSlot *slot,
{
ResultRelInfo *resultRelInfo;
Relation resultRelationDesc;
ItemPointerData ctid;
int result;
ItemPointerData update_ctid;
TransactionId update_xmax;
/*
* get information on the (current) result relation
@ -1307,7 +1315,7 @@ ExecDelete(TupleTableSlot *slot,
*/
ldelete:;
result = heap_delete(resultRelationDesc, tupleid,
&ctid,
&update_ctid, &update_xmax,
estate->es_snapshot->curcid);
switch (result)
{
@ -1321,14 +1329,17 @@ ldelete:;
case HeapTupleUpdated:
if (XactIsoLevel == XACT_SERIALIZABLE)
elog(ERROR, "Can't serialize access due to concurrent update");
else if (!(ItemPointerEquals(tupleid, &ctid)))
else if (!ItemPointerEquals(tupleid, &update_ctid))
{
TupleTableSlot *epqslot = EvalPlanQual(estate,
resultRelInfo->ri_RangeTableIndex, &ctid);
TupleTableSlot *epqslot;
epqslot = EvalPlanQual(estate,
resultRelInfo->ri_RangeTableIndex,
&update_ctid,
update_xmax);
if (!TupIsNull(epqslot))
{
*tupleid = ctid;
*tupleid = update_ctid;
goto ldelete;
}
}
@ -1376,8 +1387,9 @@ ExecUpdate(TupleTableSlot *slot,
HeapTuple tuple;
ResultRelInfo *resultRelInfo;
Relation resultRelationDesc;
ItemPointerData ctid;
int result;
ItemPointerData update_ctid;
TransactionId update_xmax;
int numIndices;
/*
@ -1443,7 +1455,7 @@ lreplace:;
* replace the heap tuple
*/
result = heap_update(resultRelationDesc, tupleid, tuple,
&ctid,
&update_ctid, &update_xmax,
estate->es_snapshot->curcid);
switch (result)
{
@ -1457,14 +1469,17 @@ lreplace:;
case HeapTupleUpdated:
if (XactIsoLevel == XACT_SERIALIZABLE)
elog(ERROR, "Can't serialize access due to concurrent update");
else if (!(ItemPointerEquals(tupleid, &ctid)))
else if (!(ItemPointerEquals(tupleid, &update_ctid)))
{
TupleTableSlot *epqslot = EvalPlanQual(estate,
resultRelInfo->ri_RangeTableIndex, &ctid);
TupleTableSlot *epqslot;
epqslot = EvalPlanQual(estate,
resultRelInfo->ri_RangeTableIndex,
&update_ctid,
update_xmax);
if (!TupIsNull(epqslot))
{
*tupleid = ctid;
*tupleid = update_ctid;
tuple = ExecRemoveJunk(estate->es_junkFilter, epqslot);
slot = ExecStoreTuple(tuple,
estate->es_junkFilter->jf_resultSlot,
@ -1606,9 +1621,21 @@ ExecConstraints(const char *caller, ResultRelInfo *resultRelInfo,
* under READ COMMITTED rules.
*
* See backend/executor/README for some info about how this works.
*
* estate - executor state data
* rti - rangetable index of table containing tuple
* *tid - t_ctid from the outdated tuple (ie, next updated version)
* priorXmax - t_xmax from the outdated tuple
*
* *tid is also an output parameter: it's modified to hold the TID of the
* latest version of the tuple (note this may be changed even on failure)
*
* Returns a slot containing the new candidate update/delete tuple, or
* NULL if we determine we shouldn't process the row.
*/
TupleTableSlot *
EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
EvalPlanQual(EState *estate, Index rti,
ItemPointer tid, TransactionId priorXmax)
{
evalPlanQual *epq;
EState *epqstate;
@ -1653,10 +1680,24 @@ EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
{
Buffer buffer;
if (heap_fetch(relation, SnapshotDirty, &tuple, &buffer, false, NULL))
if (heap_fetch(relation, SnapshotDirty, &tuple, &buffer, true, NULL))
{
TransactionId xwait = SnapshotDirty->xmax;
/*
* If xmin isn't what we're expecting, the slot must have been
* recycled and reused for an unrelated tuple. This implies
* that the latest version of the row was deleted, so we need
* do nothing. (Should be safe to examine xmin without getting
* buffer's content lock, since xmin never changes in an existing
* tuple.)
*/
if (!TransactionIdEquals(HeapTupleHeaderGetXmin(tuple.t_data),
priorXmax))
{
ReleaseBuffer(buffer);
return NULL;
}
/* otherwise xmin should not be dirty... */
if (TransactionIdIsValid(SnapshotDirty->xmin))
elog(ERROR, "EvalPlanQual: t_xmin is uncommitted ?!");
@ -1664,11 +1705,11 @@ EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
* If tuple is being updated by other transaction then we have
* to wait for its commit/abort.
*/
if (TransactionIdIsValid(xwait))
if (TransactionIdIsValid(SnapshotDirty->xmax))
{
ReleaseBuffer(buffer);
XactLockTableWait(xwait);
continue;
XactLockTableWait(SnapshotDirty->xmax);
continue; /* loop back to repeat heap_fetch */
}
/*
@ -1680,22 +1721,50 @@ EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
}
/*
* Oops! Invalid tuple. Have to check is it updated or deleted.
* Note that it's possible to get invalid SnapshotDirty->tid if
* tuple updated by this transaction. Have we to check this ?
* If the referenced slot was actually empty, the latest version
* of the row must have been deleted, so we need do nothing.
*/
if (ItemPointerIsValid(&(SnapshotDirty->tid)) &&
!(ItemPointerEquals(&(tuple.t_self), &(SnapshotDirty->tid))))
if (tuple.t_data == NULL)
{
/* updated, so look at the updated copy */
tuple.t_self = SnapshotDirty->tid;
continue;
ReleaseBuffer(buffer);
return NULL;
}
/*
* Deleted or updated by this transaction; forget it.
* As above, if xmin isn't what we're expecting, do nothing.
*/
return NULL;
if (!TransactionIdEquals(HeapTupleHeaderGetXmin(tuple.t_data),
priorXmax))
{
ReleaseBuffer(buffer);
return NULL;
}
/*
* If we get here, the tuple was found but failed SnapshotDirty.
* Assuming the xmin is either a committed xact or our own xact
* (as it certainly should be if we're trying to modify the tuple),
* this must mean that the row was updated or deleted by either
* a committed xact or our own xact. If it was deleted, we can
* ignore it; if it was updated then chain up to the next version
* and repeat the whole test.
*
* As above, it should be safe to examine xmax and t_ctid without
* the buffer content lock, because they can't be changing.
*/
if (ItemPointerEquals(&tuple.t_self, &tuple.t_data->t_ctid))
{
/* deleted, so forget about it */
ReleaseBuffer(buffer);
return NULL;
}
/* updated, so look at the updated row */
tuple.t_self = tuple.t_data->t_ctid;
/* updated row should have xmin matching this xmax */
priorXmax = HeapTupleHeaderGetXmax(tuple.t_data);
ReleaseBuffer(buffer);
/* loop back to fetch next in chain */
}
/*

11
src/backend/utils/time/tqual.c
View File

@ -30,7 +30,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/time/tqual.c,v 1.61.2.1 2005/05/07 21:23:24 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/time/tqual.c,v 1.61.2.2 2005/08/26 20:07:17 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -931,10 +931,13 @@ HeapTupleSatisfiesVacuum(HeapTupleHeader tuple, TransactionId OldestXmin)
HeapTupleHeaderGetXmax(tuple)))
{
/*
* inserter also deleted it, so it was never visible to anyone
* else
* Inserter also deleted it, so it was never visible to anyone
* else. However, we can only remove it early if it's not an
* updated tuple; else its parent tuple is linking to it via t_ctid,
* and this tuple mustn't go away before the parent does.
*/
return HEAPTUPLE_DEAD;
if (!(tuple->t_infomask & HEAP_UPDATED))
return HEAPTUPLE_DEAD;
}
if (!TransactionIdPrecedes(HeapTupleHeaderGetXmax(tuple), OldestXmin))

20
src/include/access/heapam.h
View File

@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: heapam.h,v 1.79 2002/09/04 20:31:36 momjian Exp $
* $Id: heapam.h,v 1.79.2.1 2005/08/26 20:07:17 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -156,17 +156,21 @@ extern bool heap_fetch(Relation relation, Snapshot snapshot,
HeapTuple tuple, Buffer *userbuf, bool keep_buf,
PgStat_Info *pgstat_info);
extern ItemPointer heap_get_latest_tid(Relation relation, Snapshot snapshot,
extern void heap_get_latest_tid(Relation relation, Snapshot snapshot,
ItemPointer tid);
extern void setLastTid(const ItemPointer tid);
extern Oid heap_insert(Relation relation, HeapTuple tup, CommandId cid);
extern int heap_delete(Relation relation, ItemPointer tid, ItemPointer ctid,
CommandId cid);
extern int heap_update(Relation relation, ItemPointer otid, HeapTuple tup,
ItemPointer ctid, CommandId cid);
extern int heap_mark4update(Relation relation, HeapTuple tup,
Buffer *userbuf, CommandId cid);
extern int heap_delete(Relation relation, ItemPointer tid,
ItemPointer ctid, TransactionId *update_xmax,
CommandId cid);
extern int heap_update(Relation relation, ItemPointer otid,
HeapTuple newtup,
ItemPointer ctid, TransactionId *update_xmax,
CommandId cid);
extern int heap_mark4update(Relation relation, HeapTuple tuple,
Buffer *buffer, ItemPointer ctid,
TransactionId *update_xmax, CommandId cid);
extern Oid simple_heap_insert(Relation relation, HeapTuple tup);
extern void simple_heap_delete(Relation relation, ItemPointer tid);

4
src/include/executor/executor.h
View File

@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: executor.h,v 1.78 2002/09/04 20:31:42 momjian Exp $
* $Id: executor.h,v 1.78.2.1 2005/08/26 20:07:17 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -55,7 +55,7 @@ extern void ExecutorEnd(QueryDesc *queryDesc, EState *estate);
extern void ExecConstraints(const char *caller, ResultRelInfo *resultRelInfo,
TupleTableSlot *slot, EState *estate);
extern TupleTableSlot *EvalPlanQual(EState *estate, Index rti,
ItemPointer tid);
ItemPointer tid, TransactionId priorXmax);
/*
* prototypes from functions in execProcnode.c