Re: [HACKERS] [PATCH] Use $ parameters as replacement characters forpg_stat_statements

On Sat, Mar  4, 2017 at 10:52:44AM -0800, Peter Geoghegan wrote:
> On Sat, Mar 4, 2017 at 8:02 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> > Meh ... we've generally regretted it when we "solved" a backwards
> > compatibility problem by introducing a GUC that changes query semantics.
> > I'm inclined to think we should either do it or not.
> 
> In my opinion, we expose query id (and dbid, and userid) as the
> canonical identifier for each pg_stat_statements entry, and have done
> so for some time. That's the stable API -- not query text. I'm aware
> of cases where query text was used as an identifier, but that ended up
> being hashed anyway.

Speaking of hash values for queries, someone once asked me if we could
display a hash value for queries displayed in pg_stat_activity and
pg_stat_statements so they could take a running query and look in
pg_stat_statements to see how long is usually ran.  It seemed like a
useful idea to me.

I don't think they can hash the query manually because of the constants
involved.

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com

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