Re: question about pg_dump

2009/10/22 Grzegorz Jaśkiewicz <gryzman(at)gmail(dot)com>:
>
>
> On Thu, Oct 22, 2009 at 3:42 PM, Scot Kreienkamp <SKreien(at)la-z-boy(dot)com>
> wrote:
>>
>> Hi everyone,
>>
>>
>>
>> I have a question about pg_dump backups.  Will changes made in the
>> database made during a pg_dump operation be reflected in the dumped
>> datafile?  Or is the data the exact dataset that was in the database as of
>> the start of the backup?
>
> pg_dump opens transaction, on a serializable isolation level. In short, it
> is the proper full isolation level (as oppose to the default one: "read
> committed"). It can cause locks up on database, but the idea is that the
> dump it self is a snapshot, and is fully atomic.

Only DDL type stuff should be locked. Regular updates / inserts /
delete should run just fine during a backup.