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Push the responsibility for handling ignore_killed_tuples down into

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_bt_checkkeys(), instead of checking it in the top-level nbtree.c routines
as formerly.  This saves a little bit of loop overhead, but more importantly
it lets us skip performing the index key comparisons for dead tuples.
This commit is contained in:
Tom Lane
2005-12-07 19:37:53 +00:00
parent f1b059af12
commit cefcbbf1fd
4 changed files with 72 additions and 72 deletions
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72
src/backend/access/nbtree/nbtutils.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtutils.c,v 1.66 2005/11/22 18:17:06 momjian Exp $
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtutils.c,v 1.67 2005/12/07 19:37:53 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -477,30 +477,77 @@ _bt_preprocess_keys(IndexScanDesc scan)
/*
* Test whether an indextuple satisfies all the scankey conditions.
*
* If so, copy its TID into scan->xs_ctup.t_self, and return TRUE.
* If not, return FALSE (xs_ctup is not changed).
*
* If the tuple fails to pass the qual, we also determine whether there's
* any need to continue the scan beyond this tuple, and set *continuescan
* accordingly. See comments for _bt_preprocess_keys(), above, about how
* this is done.
*
* scan: index scan descriptor
* page: buffer page containing index tuple
* offnum: offset number of index tuple (must be a valid item!)
* dir: direction we are scanning in
* continuescan: output parameter (will be set correctly in all cases)
*/
bool
_bt_checkkeys(IndexScanDesc scan, IndexTuple tuple,
_bt_checkkeys(IndexScanDesc scan,
Page page, OffsetNumber offnum,
ScanDirection dir, bool *continuescan)
{
BTScanOpaque so = (BTScanOpaque) scan->opaque;
int keysz = so->numberOfKeys;
int ikey;
ItemId iid = PageGetItemId(page, offnum);
bool tuple_valid;
BTItem btitem;
IndexTuple tuple;
TupleDesc tupdesc;
BTScanOpaque so;
int keysz;
int ikey;
ScanKey key;
*continuescan = true;
*continuescan = true; /* default assumption */
/* If no keys, always scan the whole index */
if (keysz == 0)
return true;
/*
* If the scan specifies not to return killed tuples, then we treat
* a killed tuple as not passing the qual. Most of the time, it's a
* win to not bother examining the tuple's index keys, but just return
* immediately with continuescan = true to proceed to the next tuple.
* However, if this is the last tuple on the page, we should check
* the index keys to prevent uselessly advancing to the next page.
*/
if (scan->ignore_killed_tuples && ItemIdDeleted(iid))
{
/* return immediately if there are more tuples on the page */
if (ScanDirectionIsForward(dir))
{
if (offnum < PageGetMaxOffsetNumber(page))
return false;
}
else
{
BTPageOpaque opaque = (BTPageOpaque) PageGetSpecialPointer(page);
if (offnum > P_FIRSTDATAKEY(opaque))
return false;
}
/*
* OK, we want to check the keys, but we'll return FALSE even
* if the tuple passes the key tests.
*/
tuple_valid = false;
}
else
tuple_valid = true;
btitem = (BTItem) PageGetItem(page, iid);
tuple = &btitem->bti_itup;
IncrIndexProcessed();
tupdesc = RelationGetDescr(scan->indexRelation);
so = (BTScanOpaque) scan->opaque;
keysz = so->numberOfKeys;
for (key = so->keyData, ikey = 0; ikey < keysz; key++, ikey++)
{
@ -592,6 +639,9 @@ _bt_checkkeys(IndexScanDesc scan, IndexTuple tuple,
}
}
/* If we get here, the tuple passes all quals. */
return true;
/* If we get here, the tuple passes all index quals. */
if (tuple_valid)
scan->xs_ctup.t_self = tuple->t_tid;
return tuple_valid;
}