Re: Running pg_dump from a slave server

On Wed, Aug 17, 2016 at 11:51 AM Patrick B <patrickbakerbr(at)gmail(dot)com> wrote:

>
>>
>> But do you have statements which causes Exclusive Locks? Ignoring them in
>> OLTP won't make your life any easier.
>>
>> (Keeping avoiding to get into 'recovery conflict' as your sole goal) If
>> you decide to run pg_dump from master, it would block such statements
>> which have Exclusive locking. This would cause delays, deadlocks, livelocks
>> etc and it might take a while for your before you can figure out what is
>> going on.
>>
>> I would say try to find out who is and why is someone creating Exclusive
>> locks.
>>
>
>
> Yeah! The pg_dump was already running on the master... it's been running
> for months.. I just wanted to change now to use the slave, but it seems I
> can't right?
>
>
Not unless you find what is causing the conflict or you are ready to live
with delay in promotion when master goes down.

> Exclusive locking - I probably have statements that causes this. Is there
> any way I could "track" them?
>

Do you have-

1. DML operations changing large portions of a table at once - it might
lead a page level lock which might conflict with SELECT/share locks on
standby
2. Any REINDEX operations
3. DDL operation
4. VACUUM FULL

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