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Restructure LOCKTAG as per discussions of a couple months ago.

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Essentially, we shoehorn in a lockable-object-type field by taking
a byte away from the lockmethodid, which can surely fit in one byte
instead of two.  This allows less artificial definitions of all the
other fields of LOCKTAG; we can get rid of the special pg_xactlock
pseudo-relation, and also support locks on individual tuples and
general database objects (including shared objects).  None of those
possibilities are actually exploited just yet, however.

I removed pg_xactlock from pg_class, but did not force initdb for
that change.  At this point, relkind 's' (SPECIAL) is unused and
could be removed entirely.
This commit is contained in:
Tom Lane
2005-04-29 22:28:24 +00:00
parent 32d3b47e6f
commit 3a694bb0a1
14 changed files with 347 additions and 255 deletions
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11
src/backend/access/heap/hio.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/heap/hio.c,v 1.54 2004/12/31 21:59:16 pgsql Exp $
* $PostgreSQL: pgsql/src/backend/access/heap/hio.c,v 1.55 2005/04/29 22:28:23 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -79,11 +79,6 @@ RelationPutHeapTuple(Relation relation,
* happen if space is freed in that page after heap_update finds there's not
* enough there). In that case, the page will be pinned and locked only once.
*
* Note that we use LockPage(rel, 0) to lock relation for extension.
* We can do this as long as in all other places we use page-level locking
* for indices only. Alternatively, we could define pseudo-table as
* we do for transactions with XactLockTable.
*
* ereport(ERROR) is allowed here, so this routine *must* be called
* before any (unlogged) changes are made in buffer pool.
*/
@ -235,7 +230,7 @@ RelationGetBufferForTuple(Relation relation, Size len,
needLock = !RELATION_IS_LOCAL(relation);
if (needLock)
LockPage(relation, 0, ExclusiveLock);
LockRelationForExtension(relation, ExclusiveLock);
/*
* XXX This does an lseek - rather expensive - but at the moment it is
@ -251,7 +246,7 @@ RelationGetBufferForTuple(Relation relation, Size len,
* extend the relation some more.
*/
if (needLock)
UnlockPage(relation, 0, ExclusiveLock);
UnlockRelationForExtension(relation, ExclusiveLock);
/*
* We can be certain that locking the otherBuffer first is OK, since