Re: Cluster feature: Start/stop archiving at runtime

> Tatsuo Ishii wrote:
> >> Since I didn't hear anything about "API into the Parser / Parser as an
> >> independent module", I just wrote my own summary of what I think the
> >> idea was there is and am moving on.  I'll try to track down more info at
> >> PG East next month when I run into some of the people I think care about
> >> this.
> >>
> >
> > I have took a look at your description. That is totally different from
> > what I thought. Statement replication and/or load balancing middle
> > ware need to know SQL statement is SELECT or others. If it is a (read
> > only) SELECT, it can be routed to standby node of Streaming
> > replication clusters for example. For this purpose, such a middle ware
> > ought to be able to parse SQL. If PostgreSQL provide its raw parser as
> > a C library, it will be very usefull for such middle ware since they
> > do not need to re-implement their own SQL parser (as pgpool-II already
> > did).
> >
> >
>
> I never claimed I really understand what entry was alluding to and just
> made the first wild guess that came to mind.  I'll be happy to replace
> it with the alternate explanation you suggested for what it was intended
> to address.  The part I still don't see is how these two comments in
> that section fit into what you're describing here:
>
> * statement based replication need to replay certain constructs with
> CONSTANT values you provide
> * Figure out which you need to replace... quite difficult

I guess these are talking about server internally generated values:
i.e. CURRENT_TIMESTAMP, sequence, oid, random() and so on (Pgpool-II
recently solved problems with CURRENT_TIMESTAMP and large object oid
BTW). To solve the problem we need a SQL parser to find out certain
constructs needed to be replaced with CONSTANT.

> Those are the parts I was basing my guess as to the intended application
> here on.  If this is just intended to improve relaying SELECT statements
> over to another node, why would you need to replace anything with
> constants or other values?
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp