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Re: svn commit: r1081484 - in /subversion/trunk/subversion/libsvn_wc: wc-queries.sql wc_db.c

From: Stefan Sperling <stsp_at_elego.de>
Date: Mon, 28 Mar 2011 15:30:55 +0200

On Mon, Mar 28, 2011 at 08:42:02AM -0400, Greg Stein wrote:
> On Mar 28, 2011 8:32 AM, "Stefan Sperling" <stsp_at_elego.de> wrote:
> >
> > On Mon, Mar 28, 2011 at 07:49:22AM -0400, Greg Stein wrote:
> > > On Mar 28, 2011 7:41 AM, "Greg Stein" <gstein_at_gmail.com> wrote:
> > > > Think about how the query optimizer/planner would work. Consider
> whether a
> > > result set needs to be constructed.
> > > >
> > > > ... a LIMIT 1 provides a ton of help to the SQL engine about what
> needs to
> > > be fetched (or not).
> > > >
> > > > There is also a semantic element to it. Readers of the code will see
> that
> > > you're looking for basic presence rather than a set of results.
> > > >
> > > > If/when you need a query containing the set of nodes with mods, then
> you
> > > can consider another query. Until that time, the LIMIT is helpful/best.
> > > >
> > > > Cheers,
> > > > -g
> > >
> > > In fact, you can switch from selecting local_relpath to a simple 1:
> > >
> > > --STMT_ANY_NODES_WITH_PROP_MODS
> > > SELECT 1 FROM ...
> > >
> > > (note stmt name change, too)
> >
> > Fair enough. Does r1086208 look better?
>
> I like the new names, but the LIMIT didn't make it into the commit :-)

Didn't you imply that SELECT 1 has the same effect as LIMIT 1?
Or did I misunderstand?
Received on 2011-03-28 15:31:31 CEST

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