[pgpool-hackers: 1619] Re: Redirecting queries to standby as much as possible

[Yugo Nagata]

On Fri, 10 Jun 2016 16:48:19 +0900 (JST)
Tatsuo Ishii <ishii at postgresql.org> wrote:

> > On Fri, 10 Jun 2016 15:13:19 +0900 (JST)
> > Tatsuo Ishii <ishii at postgresql.org> wrote:
> > 
> >> Submitter of bug 195 (http://www.pgpool.net/mantisbt/view.php?id=195)
> >> wants to redirect queries to standby as much as possible if the
> >> transaction is read only. This brings up interesting conflicts to
> >> current behavior of pgpool-II:
> >> 
> >> - the weight parameters of backend info needs to be ignored if the
> >>   transaction is read only
> >> 
> >> - black and white function list need to be ignored if the transaction
> >>   is read only
> >> 
> >> - database_redirect_preference_list needs to be ignored if the
> >>   transaction is read only
> >> 
> >> - app_name_redirect_preference_list needs to be ignored if the
> >>   transaction is read only
> >> 
> >> After all, if we don't want to confuse existing users in the use cases
> >> above, we need to invent a new switch to change the redirecting
> >> behavior depending on whether the transaction is read only or not.
> > 
> > I agree that to add new switch is good because it is simple and preserves
> > compatibility.
> 
> Question is, whether it's worth the trouble. Is there any people other
> than the bug submitter who wants the feature?

I also doubt the needs, but someone might want a transaction including
SET to be sent to standby. We might get user's opinions about the feature
from pgpool-general rather than pgpool-hackers.

> 
> > However, even in the current version, the priority of the above rules is
> > confusing. I think the priority rule should be summarized in the document
> > explicitly.
> 
> Welcome volunteering the work:-)

Anyone? ... me? :-}

> 
> Best regards,
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese:http://www.sraoss.co.jp


-- 
Yugo Nagata <nagata at sraoss.co.jp>