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Redefine the lp_flags field of item pointers as having four states, rather

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than two independent bits (one of which was never used in heap pages anyway,
or at least hadn't been in a very long time).  This gives us flexibility to
add the HOT notions of redirected and dead item pointers without requiring
anything so klugy as magic values of lp_off and lp_len.  The state values
are chosen so that for the states currently in use (pre-HOT) there is no
change in the physical representation.
This commit is contained in:
Tom Lane
2007-09-12 22:10:26 +00:00
parent eb0a7735ba
commit 6889303531
31 changed files with 278 additions and 185 deletions
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12
src/backend/access/nbtree/nbtutils.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtutils.c,v 1.85 2007/04/09 22:04:01 tgl Exp $
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtutils.c,v 1.86 2007/09/12 22:10:26 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -789,7 +789,7 @@ _bt_checkkeys(IndexScanDesc scan,
* 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))
if (scan->ignore_killed_tuples && ItemIdIsDead(iid))
{
/* return immediately if there are more tuples on the page */
if (ScanDirectionIsForward(dir))
@ -1088,7 +1088,7 @@ _bt_check_rowcompare(ScanKey skey, IndexTuple tuple, TupleDesc tupdesc,
}
/*
* _bt_killitems - set LP_DELETE bit for items an indexscan caller has
* _bt_killitems - set LP_DEAD state for items an indexscan caller has
* told us were killed
*
* scan->so contains information about the current page and killed tuples
@ -1096,7 +1096,7 @@ _bt_check_rowcompare(ScanKey skey, IndexTuple tuple, TupleDesc tupdesc,
*
* The caller must have pin on so->currPos.buf, but may or may not have
* read-lock, as indicated by haveLock. Note that we assume read-lock
* is sufficient for setting LP_DELETE hint bits.
* is sufficient for setting LP_DEAD status (which is only a hint).
*
* We match items by heap TID before assuming they are the right ones to
* delete. We cope with cases where items have moved right due to insertions.
@ -1149,7 +1149,7 @@ _bt_killitems(IndexScanDesc scan, bool haveLock)
if (ItemPointerEquals(&ituple->t_tid, &kitem->heapTid))
{
/* found the item */
iid->lp_flags |= LP_DELETE;
ItemIdMarkDead(iid);
killedsomething = true;
break; /* out of inner search loop */
}
@ -1162,7 +1162,7 @@ _bt_killitems(IndexScanDesc scan, bool haveLock)
* commit-hint-bit status update for heap tuples: we mark the buffer dirty
* but don't make a WAL log entry.
*
* Whenever we mark anything LP_DELETEd, we also set the page's
* Whenever we mark anything LP_DEAD, we also set the page's
* BTP_HAS_GARBAGE flag, which is likewise just a hint.
*/
if (killedsomething)