From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Vadim Mikheev <vadim(at)krs(dot)ru> |
Cc: | pgsql-hackers(at)postgreSQL(dot)org |
Subject: | Re: [HACKERS] It sorta works, but I'm confused about locking |
Date: | 1998-10-02 01:47:13 |
Message-ID: | 29738.907292833@sss.pgh.pa.us |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
Vadim Mikheev <vadim(at)krs(dot)ru> writes:
> Tom Lane wrote:
>> I guess I'm not understanding something. How can it ever be correct
>> practice to release a lock before transaction end? For example, if I
>> write some changes in a table, and then release the lock, wouldn't that
>> allow other backends to see the not-yet-committed changes? What if I
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> No. Backend uses xmin/xmax to know is tuple visible or not.
Ah, some light dawns. Thanks for the clue!
> Postgres does this for system tables only.
OK, so what is good coding practice? Always release write lock after
operating on a system table? Or is that only good some of the time,
and if so what's the consideration?
regards, tom lane
From | Date | Subject | |
---|---|---|---|
Next Message | Bruce Momjian | 1998-10-02 01:48:59 | Re: [HACKERS] SQL92 |
Previous Message | Tom Lane | 1998-10-02 01:42:01 | Re: [HACKERS] Patch for libpgtcl |