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

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

View File

@@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtpage.c,v 1.102 2007/01/05 22:19:23 momjian Exp $
* $PostgreSQL: pgsql/src/backend/access/nbtree/nbtpage.c,v 1.103 2007/09/12 22:10:26 tgl Exp $
*
* NOTES
* Postgres btree pages look like ordinary relation pages. The opaque
@@ -669,7 +669,7 @@ _bt_delitems(Relation rel, Buffer buf,
opaque->btpo_cycleid = 0;
/*
* Mark the page as not containing any LP_DELETE items. This is not
* Mark the page as not containing any LP_DEAD items. This is not
* certainly true (there might be some that have recently been marked, but
* weren't included in our target-item list), but it will almost always be
* true and it doesn't seem worth an additional page scan to check it.