2015-11-04 23:53 GMT+01:00 Stephen Frost <sfr...@snowman.net>:
> On Wednesday, November 4, 2015, Joshua D. Drake <j...@commandprompt.com>
>> On 11/04/2015 02:15 PM, Stephen Frost wrote:
>> Yeah but anything holding a lock that long can be terminated via
>>>> statement_timeout can it not?
>>> Well, no? statement_timeout is per-statement, while transaction_timeout
>>> is, well, per transaction. If there's a process which is going and has
>>> an open transaction and it's holding locks, that can be an issue.
>> No, what I mean is this:
>> select * from foo;
>> update bar;
>> delete baz;
>> Each one of those is subject to statement_timeout, yes? If so, then I
>> don't see a point for transaction timeout. You set statement_timeout for
>> what works for your environment. Once the timeout is reached within the
>> statement (within the transaction), the transaction is going to rollback
> This implies that a statement used takes a long time. It may not. The lock
> is held at the transaction level not the statement level, which is why a
> transaction level timeout is actually more useful than a statement level
It hard to compare these proposals because any proposal solves slightly
different issue and has different advantages and disadvantages. The flat
solution probably will by too limited. I see a possible advantages of
transaction_timeout (max lock duration), transaction_idle_timeout,
statement_timeout. Any of these limits has sense, and can helps with
resource management. There is not full substitution.
> What I'm most interested in, in the use case which I described and which
> David built a system for, is getting that lock released from the lower
> priority process to let the higher priority process run. I couldn't care
> less about statement level anything.