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Mark index entries "killed" when they are no longer visible to any

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transaction, so as to avoid returning them out of the index AM.  Saves
repeated heap_fetch operations on frequently-updated rows.  Also detect
queries on unique keys (equality to all columns of a unique index), and
don't bother continuing scan once we have found first match.

Killing is implemented in the btree and hash AMs, but not yet in rtree
or gist, because there isn't an equally convenient place to do it in
those AMs (the outer amgetnext routine can't do it without re-pinning
the index page).

Did some small cleanup on APIs of HeapTupleSatisfies, heap_fetch, and
index_insert to make this a little easier.
This commit is contained in:
Tom Lane
2002-05-24 18:57:57 +00:00
parent 2f2d05763d
commit 3f4d488022
30 changed files with 498 additions and 273 deletions
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99
src/backend/access/heap/heapam.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/access/heap/heapam.c,v 1.135 2002/05/21 22:05:53 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/access/heap/heapam.c,v 1.136 2002/05/24 18:57:55 tgl Exp $
*
*
* INTERFACE ROUTINES
@ -306,6 +306,8 @@ heapgettup(Relation relation,
{
if (ItemIdIsUsed(lpp))
{
bool valid;
tuple->t_datamcxt = NULL;
tuple->t_data = (HeapTupleHeader) PageGetItem((Page) dp, lpp);
tuple->t_len = ItemIdGetLength(lpp);
@ -315,8 +317,8 @@ heapgettup(Relation relation,
* if current tuple qualifies, return it.
*/
HeapTupleSatisfies(tuple, relation, *buffer, (PageHeader) dp,
snapshot, nkeys, key);
if (tuple->t_data != NULL)
snapshot, nkeys, key, valid);
if (valid)
{
LockBuffer(*buffer, BUFFER_LOCK_UNLOCK);
return;
@ -864,32 +866,37 @@ heap_getnext(HeapScanDesc scan, ScanDirection direction)
return ((scan->rs_ctup.t_data == NULL) ? NULL : &(scan->rs_ctup));
}
/* ----------------
* heap_fetch - retrieve tuple with given tid
/*
* heap_fetch - retrieve tuple with given tid
*
* On entry, tuple->t_self is the TID to fetch.
* On entry, tuple->t_self is the TID to fetch. We pin the buffer holding
* the tuple, fill in the remaining fields of *tuple, and check the tuple
* against the specified snapshot.
*
* If successful (ie, tuple found and passes snapshot time qual),
* then the rest of *tuple is filled in, and *userbuf is set to the
* buffer holding the tuple. A pin is obtained on the buffer; the
* caller must BufferRelease the buffer when done with the tuple.
* If successful (tuple passes snapshot time qual), then *userbuf is set to
* the buffer holding the tuple and TRUE is returned. The caller must
* unpin the buffer when done with the tuple.
*
* If not successful, tuple->t_data is set to NULL and *userbuf is set to
* InvalidBuffer.
* ----------------
* If the tuple fails the time qual check, then FALSE will be returned.
* When the caller specifies keep_buf = true, we retain the pin on the
* buffer and return it in *userbuf (so the caller can still access the
* tuple); when keep_buf = false, the pin is released and *userbuf is set
* to InvalidBuffer.
*/
void
bool
heap_fetch(Relation relation,
Snapshot snapshot,
HeapTuple tuple,
Buffer *userbuf,
bool keep_buf,
PgStat_Info *pgstat_info)
{
ItemPointer tid = &(tuple->t_self);
ItemId lp;
Buffer buffer;
PageHeader dp;
ItemPointer tid = &(tuple->t_self);
OffsetNumber offnum;
bool valid;
/*
* increment access statistics
@ -901,14 +908,16 @@ heap_fetch(Relation relation,
* get the buffer from the relation descriptor. Note that this does a
* buffer pin.
*/
buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(tid));
if (!BufferIsValid(buffer))
elog(ERROR, "heap_fetch: %s relation: ReadBuffer(%ld) failed",
elog(ERROR, "heap_fetch: ReadBuffer(%s, %lu) failed",
RelationGetRelationName(relation),
(long) ItemPointerGetBlockNumber(tid));
(unsigned long) ItemPointerGetBlockNumber(tid));
/*
* Need share lock on buffer to examine tuple commit status.
*/
LockBuffer(buffer, BUFFER_LOCK_SHARE);
/*
@ -921,38 +930,34 @@ heap_fetch(Relation relation,
/*
* more sanity checks
*/
if (!ItemIdIsUsed(lp))
{
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
ReleaseBuffer(buffer);
*userbuf = InvalidBuffer;
tuple->t_datamcxt = NULL;
tuple->t_data = NULL;
return;
elog(ERROR, "heap_fetch: invalid tuple id (%s, %lu, %u)",
RelationGetRelationName(relation),
(unsigned long) ItemPointerGetBlockNumber(tid),
offnum);
}
/*
* fill in *tuple fields
*/
tuple->t_datamcxt = NULL;
tuple->t_data = (HeapTupleHeader) PageGetItem((Page) dp, lp);
tuple->t_len = ItemIdGetLength(lp);
tuple->t_tableOid = relation->rd_id;
/*
* check time qualification of tid
* check time qualification of tuple, then release lock
*/
HeapTupleSatisfies(tuple, relation, buffer, dp,
snapshot, 0, (ScanKey) NULL);
snapshot, 0, (ScanKey) NULL, valid);
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
if (tuple->t_data == NULL)
{
/* Tuple failed time check, so we can release now. */
ReleaseBuffer(buffer);
*userbuf = InvalidBuffer;
}
else
if (valid)
{
/*
* All checks passed, so return the tuple as valid. Caller is now
@ -968,13 +973,28 @@ heap_fetch(Relation relation,
pgstat_count_heap_fetch(pgstat_info);
else
pgstat_count_heap_fetch(&relation->pgstat_info);
return true;
}
/* Tuple failed time qual, but maybe caller wants to see it anyway. */
if (keep_buf)
{
*userbuf = buffer;
return false;
}
/* Okay to release pin on buffer. */
ReleaseBuffer(buffer);
*userbuf = InvalidBuffer;
return false;
}
/* ----------------
/*
* heap_get_latest_tid - get the latest tid of a specified tuple
*
* ----------------
*/
ItemPointer
heap_get_latest_tid(Relation relation,
@ -989,7 +1009,8 @@ heap_get_latest_tid(Relation relation,
HeapTupleHeader t_data;
ItemPointerData ctid;
bool invalidBlock,
linkend;
linkend,
valid;
/*
* get the buffer from the relation descriptor Note that this does a
@ -1038,7 +1059,7 @@ heap_get_latest_tid(Relation relation,
*/
HeapTupleSatisfies(&tp, relation, buffer, dp,
snapshot, 0, (ScanKey) NULL);
snapshot, 0, (ScanKey) NULL, valid);
linkend = true;
if ((t_data->t_infomask & HEAP_XMIN_COMMITTED) != 0 &&
@ -1048,7 +1069,7 @@ heap_get_latest_tid(Relation relation,
LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
ReleaseBuffer(buffer);
if (tp.t_data == NULL)
if (!valid)
{
if (linkend)
return NULL;

4
src/backend/access/heap/tuptoaster.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/access/heap/tuptoaster.c,v 1.30 2002/05/21 22:05:53 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/access/heap/tuptoaster.c,v 1.31 2002/05/24 18:57:55 tgl Exp $
*
*
* INTERFACE ROUTINES
@ -923,7 +923,7 @@ toast_save_datum(Relation rel, Datum value)
*/
idxres = index_insert(toastidx, t_values, t_nulls,
&(toasttup->t_self),
toastrel);
toastrel, toastidx->rd_uniqueindex);
if (idxres == NULL)
elog(ERROR, "Failed to insert index entry for TOAST tuple");