* Buffer refcount cleanup (per my "progress report" to pghackers, 9/22).
* Add links to backend PROC structs to sinval's array of per-backend info,
and use these links for routines that need to check the state of all
backends (rather than the slow, complicated search of the ShmemIndex
hashtable that was used before). Add databaseOID to PROC structs.
* Use this to implement an interlock that prevents DESTROY DATABASE of
a database containing running backends. (It's a little tricky to prevent
a concurrently-starting backend from getting in there, since the new
backend is not able to lock anything at the time it tries to look up
its database in pg_database. My solution is to recheck that the DB is
OK at the end of InitPostgres. It may not be a 100% solution, but it's
a lot better than no interlock at all...)
* In ALTER TABLE RENAME, flush buffers for the relation before doing the
rename of the physical files, to ensure we don't get failures later from
mdblindwrt().
* Update TRUNCATE patch so that it actually compiles against current
sources :-(.
You should do "make clean all" after pulling these changes.
additional argument specifying the kind of lock to acquire/release (or
'NoLock' to do no lock processing). Ensure that all relations are locked
with some appropriate lock level before being examined --- this ensures
that relevant shared-inval messages have been processed and should prevent
problems caused by concurrent VACUUM. Fix several bugs having to do with
mismatched increment/decrement of relation ref count and mismatched
heap_open/close (which amounts to the same thing). A bogus ref count on
a relation doesn't matter much *unless* a SI Inval message happens to
arrive at the wrong time, which is probably why we got away with this
sloppiness for so long. Repair missing grab of AccessExclusiveLock in
DROP TABLE, ALTER/RENAME TABLE, etc, as noted by Hiroshi.
Recommend 'make clean all' after pulling this update; I modified the
Relation struct layout slightly.
Will post further discussion to pghackers list shortly.
neqsel now behave as per my suggestions in pghackers a few days ago.
selectivity for < > <= >= should work OK for integral types as well, but
still need work for nonintegral types. Since these routines have never
actually executed before :-(, this may result in some significant changes
in the optimizer's choices of execution plans. Let me know if you see
any serious misbehavior.
CAUTION: THESE CHANGES REQUIRE INITDB. pg_statistic table has changed.
/*
* Read above about cases when !ItemIdIsUsed(Citemid)
* (child item is removed)... Due to the fact that
* at the moment we don't remove unuseful part of
* update-chain, it's possible to get too old
* parent row here. Like as in the case which
* caused this problem, we stop shrinking here.
* I could try to find real parent row but want
* not to do it because of real solution will
* be implemented anyway, latter, and we are too
* close to 6.5 release. - vadim 06/11/99
*/
if (Ptp.t_data->t_xmax != tp.t_data->t_xmin)
...
and possibly for other cases too:
DO NOT cache status of transaction in unknown state
(i.e. non-committed and non-aborted ones)
Example:
T1 reads row updated/inserted by running T2 and cache T2 status.
T2 commits.
Now T1 reads a row updated by T2 and with HEAP_XMAX_COMMITTED
in t_infomask (so cached T2 status is not changed).
Now T1 EvalPlanQual gets updated row version without HEAP_XMIN_COMMITTED
-> TransactionIdDidCommit(t_xmin) and TransactionIdDidAbort(t_xmin)
return FALSE and T2 decides that t_xmin is not committed and gets
ERROR above.
It's too late to find more smart way to handle such cases and so
I just changed xact status caching and got rid TransactionIdFlushCache()
from code.
Changed: transam.c, xact.c, lmgr.c and transam.h - last three
just because of TransactionIdFlushCache() is removed.
2. heapam.c:
T1 marked a row for update. T2 waits for T1 commit/abort.
T1 commits. T3 updates the row before T2 locks row page.
Now T2 sees that new row t_xmax is different from xact id (T1)
T2 was waiting for. Old code did Assert here. New one goes to
HeapTupleSatisfiesUpdate. Obvious changes too.
3. Added Assert to vacuum.c
4. bufmgr.c: break
Assert(buf->r_locks == 0 && !buf->ri_lock)
into two Asserts.
2. varsup.c:ReadNewTransactionId(): don't read nextXid from disk -
this func doesn't allocate next xid, so ShmemVariableCache->nextXid
may be used (but GetNewTransactionId() must be called first).
3. vacuum.c: change elog(ERROR, "Child item....") to elog(NOTICE) -
this is not ERROR, proper handling is just not implemented, yet.
4. s_lock.c: increase S_MAX_BUSY by 2 times.
5. shmem.c:GetSnapshotData(): have to call ReadNewTransactionId()
_after_ SpinAcquire(ShmemIndexLock).
2. Get rid of locking when updating statistics in vacuum.
3. Use QuerySnapshot in COPY TO and call SetQuerySnashot
in main tcop loop before FETCH and COPY TO.
to save a little bit of backend startup time. This way, the first
backend started after a VACUUM will rebuild the init file with up-to-date
statistics for the critical system indexes.
2. Much faster btree tuples deletion in the case when first on page
index tuple is deleted (no movement to the left page(s)).
3. Remember blkno of new root page in BTPageOpaque of
left/right siblings when root page is splitted.
Here are two new patches for the Win32 support.
1) The patch based on the one from Hiroshi Inoue [Inoue@tpf.co.jp], to
load
Winsock.dll from libpq.dll.
2) A patch for psql.c to remove the call to WSAStartup(), since it is
not
required when it's done in libpq.dll.
I'm still looking for the possibility of having a crypt() function in
libpq.dll too, the same way getopt was included. Any chance of getting
this
before 6.4, or should we wait for the next one?
//Magnus
I don't know if this is really related to the initdb problem
discussion (haven't followed it enough). But seems so because
it fixes a damn problem during index tuple insertion on
CREATE TABLE into pg_attribute_relid_attnum_index.
Anyway - this bug was really hard to find. During startup the
relcache reads in some prepared information about index
strategies from a file and then reinitializes the function
pointers inside the scanKey data. But for sake it assumed
single attribute index tuples (hasn't that changed recently).
Thus not all the strategies scanKey entries where initialized
properly, resulting in invalid addresses for the btree
comparision functions.
With the patch at the end the regression tests passed
excellent except for the sanity_check that crashed at vacuum
and the misc test where the select unique1 from onek2 outputs
the two rows in different order.
Jan
Vadim B. Mikheev