Re: Documentation Update: Document pg_start_backup checkpoint behavior

Tom Lane wrote:
> Bruce Momjian <bruce@momjian.us> writes:
>> There was talk about making pg_start_backup do an immediate checkpoint
>> but there was some discussion that you wouldn't want an I/O storm from
>> pg_start_backup().  However, figuring you are going to do the tar backup
>> anyway, the pg_start_backup I/O seems trivial.

Good point.

> The solution Heikki is proposing is to let the user choose immediate
> or slow checkpoint.  I agree that there's not much point in the latter
> if you are using something dumb like tar to take the filesystem backup,
> but maybe the user has something smarter that won't cause such a big
> I/O storm.

If the user is knowledgeable enough to use a smarter backup tool, he's 
probably knowledgeable enough to put pg_start_backup('foo', true) 
instead of just pg_start_backup('foo') in his scripts. But a new user 
who's just playing around and making his first backup, probably using 
tar, isn't.

--   Heikki Linnakangas  EnterpriseDB   http://www.enterprisedb.com