PROCLOCK structs in shared memory now have only a bitmask for held
locks, rather than counts (making them 40 bytes smaller, which is a
good thing). Multiple locks within a transaction are counted in the
local hash table instead, and we have provision for tracking which
ResourceOwner each count belongs to. Solves recently reported problem
with memory leakage within long transactions.
keep track of portal-related resources separately from transaction-related
resources. This allows cursors to work in a somewhat sane fashion with
nested transactions. For now, cursor behavior is non-subtransactional,
that is a cursor's state does not roll back if you abort a subtransaction
that fetched from the cursor. We might want to change that later.
performance front, but with feature freeze upon us I think it's time to
drive a stake in the ground and say that this will be in 7.5.
Alvaro Herrera, with some help from Tom Lane.
about a third, make it work on non-Windows platforms again. (But perhaps
I broke the WIN32 code, since I have no way to test that.) Fold all the
paths that fork postmaster child processes to go through the single
routine SubPostmasterMain, which takes care of resurrecting the state that
would normally be inherited from the postmaster (including GUC variables).
Clean up some places where there's no particularly good reason for the
EXEC and non-EXEC cases to work differently. Take care of one or two
FIXMEs that remained in the code.
method control structure, or a table of control structures.
. Use type LOCKMASK where an int is not a counter.
. Get rid of INVALID_TABLEID, use INVALID_LOCKMETHOD instead.
. Use INVALID_LOCKMETHOD instead of (LOCKMETHOD) NULL, because
LOCKMETHOD is not a pointer.
. Define and use macro LockMethodIsValid.
. Rename LOCKMETHOD to LOCKMETHODID.
. Remove global variable LongTermTableId in lmgr.c, because it is
never used.
. Make LockTableId static in lmgr.c, because it is used nowhere else.
Why not remove it and use DEFAULT_LOCKMETHOD?
. Rename the lock method control structure from LOCKMETHODTABLE to
LockMethodData. Introduce a pointer type named LockMethod.
. Remove elog(FATAL) after InitLockTable() call in
CreateSharedMemoryAndSemaphores(), because if something goes wrong,
there is elog(FATAL) in LockMethodTableInit(), and if this doesn't
help, an elog(ERROR) in InitLockTable() is promoted to FATAL.
. Make InitLockTable() void, because its only caller does not use its
return value any more.
. Rename variables in lock.c to avoid statements like
LockMethodTable[NumLockMethods] = lockMethodTable;
lockMethodTable = LockMethodTable[lockmethod];
. Change LOCKMETHODID type to uint16 to fit into struct LOCKTAG.
. Remove static variables BITS_OFF and BITS_ON from lock.c, because
I agree to this doubt:
* XXX is a fetch from a static array really faster than a shift?
. Define and use macros LOCKBIT_ON/OFF.
Manfred Koizar
RelOid_pg_class, and transaction locks XactLockTableId. RelId is renamed
to objId.
- LockObject() and UnlockObject() functions created, and their use
sprinkled throughout the code to do descent locking for domains and
types. They accept lock modes AccessShare and AccessExclusive, as we
only really need a 'read' and 'write' lock at the moment. Most locking
cases are held until the end of the transaction.
This fixes the cases Tom mentioned earlier in regards to locking with
Domains. If the patch is good, I'll work on cleaning up issues with
other database objects that have this problem (most of them).
Rod Taylor
available (else there's no way to interpret the list links). Change
pg_locks view to show transaction ID locks separately from ordinary
relation locks. Avoid showing N duplicate rows when the same lock is
held multiple times (seems unlikely that users care about exact hold
count). Improve documentation.
This patch is an updated version of the lock listing patch. I've made
the following changes:
- write documentation
- wrap the SRF in a view called 'pg_locks': all user-level
access should be done through this view
- re-diff against latest CVS
One thing I chose not to do is adapt the SRF to use the anonymous
composite type code from Joe Conway. I'll probably do that eventually,
but I'm not really convinced it's a significantly cleaner way to
bootstrap SRF builtins than the method this patch uses (of course, it
has other uses...)
Neil Conway
> Changes to avoid collisions with WIN32 & MFC names...
> 1. Renamed:
> a. PROC => PGPROC
> b. GetUserName() => GetUserNameFromId()
> c. GetCurrentTime() => GetCurrentDateTime()
> d. IGNORE => IGNORE_DTF in include/utils/datetime.h & utils/adt/datetim
>
> 2. Added _P to some lex/yacc tokens:
> CONST, CHAR, DELETE, FLOAT, GROUP, IN, OUT
Jan
portability issues). Caller-visible data structures are now allocated
on MAXALIGN boundaries, allowing safe use of datatypes wider than 'long'.
Rejigger hash_create API so that caller specifies size of key and
total size of entry, not size of key and size of rest of entry.
This simplifies life considerably since each number is just a sizeof(),
and padding issues etc. are taken care of automatically.
existing lock manager and spinlocks: it understands exclusive vs shared
lock but has few other fancy features. Replace most uses of spinlocks
with lightweight locks. All remaining uses of spinlocks have very short
lock hold times (a few dozen instructions), so tweak spinlock backoff
code to work efficiently given this assumption. All per my proposal on
pghackers 26-Sep-01.
do anything yet, but it has the necessary connections to initialization
and so forth. Make some gestures towards allowing number of blocks in
a relation to be BlockNumber, ie, unsigned int, rather than signed int.
(I doubt I got all the places that are sloppy about it, yet.) On the
way, replace the hardwired NLOCKS_PER_XACT fudge factor with a GUC
variable.
> Is there one LOCKMETHODCTL for every backend? I thought there was only
> one of them.
>>
>> You're right, that line is erroneous; it should read
>>
>> size += MAX_LOCK_METHODS * MAXALIGN(sizeof(LOCKMETHODCTL));
>>
>> Not a significant error but it should be changed for clarity ...
rewrite of deadlock checking. Lock holder objects are now reachable from
the associated LOCK as well as from the owning PROC. This makes it
practical to find all the processes holding a lock, as well as all those
waiting on the lock. Also, clean up some of the grottier aspects of the
SHMQueue API, and cause the waitProcs list to be stored in the intuitive
direction instead of the nonintuitive one. (Bet you didn't know that
the code followed the 'prev' link to get to the next waiting process,
instead of the 'next' link. It doesn't do that anymore.)
level" locks. A session lock is not released at transaction commit (but it
is released on transaction abort, to ensure recovery after an elog(ERROR)).
In VACUUM, use a session lock to protect the master table while vacuuming a
TOAST table, so that the TOAST table can be done in an independent
transaction.
I also took this opportunity to do some cleanup and renaming in the lock
code. The previously noted bug in ProcLockWakeup, that it couldn't wake up
any waiters beyond the first non-wakeable waiter, is now fixed. Also found
a previously unknown bug of the same kind (failure to scan all members of
a lock queue in some cases) in DeadLockCheck. This might have led to failure
to detect a deadlock condition, resulting in indefinite waits, but it's
difficult to characterize the conditions required to trigger a failure.
There's now only one transition value and transition function.
NULL handling in aggregates is a lot cleaner. Also, use Numeric
accumulators instead of integer accumulators for sum/avg on integer
datatypes --- this avoids overflow at the cost of being a little slower.
Implement VARIANCE() and STDDEV() aggregates in the standard backend.
Also, enable new LIKE selectivity estimators by default. Unrelated
change, but as long as I had to force initdb anyway...
That means you can now set your options in either or all of $PGDATA/configuration,
some postmaster option (--enable-fsync=off), or set a SET command. The list of
options is in backend/utils/misc/guc.c, documentation will be written post haste.
pg_options is gone, so is that pq_geqo config file. Also removed were backend -K,
-Q, and -T options (no longer applicable, although -d0 does the same as -Q).
Added to configure an --enable-syslog option.
changed all callers from TPRINTF to elog(DEBUG)
offended my aesthestic sensibility that there was so much unreadable code
doing so little. Rewritten code is about half the size, faster, and
(I hope) much more intelligible.
