OSDN Git Service

Fix up rickety handling of relation-truncation interlocks.
authorTom Lane <tgl@sss.pgh.pa.us>
Tue, 9 Feb 2010 21:43:30 +0000 (21:43 +0000)
committerTom Lane <tgl@sss.pgh.pa.us>
Tue, 9 Feb 2010 21:43:30 +0000 (21:43 +0000)
commitcbe9d6beb4ae1cb20c08cab29b534be4923b6768
treea9476492cd8c7eda7718f95b0ad5a45d41e55a3a
parent79647eed86cc972e80ea165dcb0b7f6fef876169
Fix up rickety handling of relation-truncation interlocks.

Move rd_targblock, rd_fsm_nblocks, and rd_vm_nblocks from relcache to the smgr
relation entries, so that they will get reset to InvalidBlockNumber whenever
an smgr-level flush happens.  Because we now send smgr invalidation messages
immediately (not at end of transaction) when a relation truncation occurs,
this ensures that other backends will reset their values before they next
access the relation.  We no longer need the unreliable assumption that a
VACUUM that's doing a truncation will hold its AccessExclusive lock until
commit --- in fact, we can intentionally release that lock as soon as we've
completed the truncation.  This patch therefore reverts (most of) Alvaro's
patch of 2009-11-10, as well as my marginal hacking on it yesterday.  We can
also get rid of assorted no-longer-needed relcache flushes, which are far more
expensive than an smgr flush because they kill a lot more state.

In passing this patch fixes smgr_redo's failure to perform visibility-map
truncation, and cleans up some rather dubious assumptions in freespace.c and
visibilitymap.c about when rd_fsm_nblocks and rd_vm_nblocks can be out of
date.
15 files changed:
src/backend/access/heap/hio.c
src/backend/access/heap/visibilitymap.c
src/backend/access/transam/xlogutils.c
src/backend/catalog/storage.c
src/backend/commands/cluster.c
src/backend/commands/sequence.c
src/backend/commands/vacuum.c
src/backend/commands/vacuumlazy.c
src/backend/executor/execMain.c
src/backend/storage/freespace/freespace.c
src/backend/storage/smgr/smgr.c
src/backend/utils/cache/relcache.c
src/include/commands/vacuum.h
src/include/storage/smgr.h
src/include/utils/rel.h