[Cl-perec-devel] Optimization question

[Mihai Bazon]

Ah.. Clear enough now, my bad for not thinking backquote. :-)

Thanks!
-Mihai

Levente Mészáros <levente.meszaros at gmail.com> wrote:
> I think I wasn't clear enough, obviously you can use `, in place of '
> 
> (let ((class-name 'foo)) ;; it's not hardcoded
>   (execute-query (make-query `(select-instances (o) (where (typep o
> ,class-name)))))
> 
> Also if you look at the generated SQL it does select prefetched slots
> too. This code fragment calls the query compiler runtime unless the
> exact same query is already compiled. In that case it looks up the
> resulting lambda from the cache.
> 
> Cheers,
> levy
> 
> 2009/10/9 Mihai Bazon <mihai at bazon.net>:
> > You hard-coded the type, which is what I want to avoid.  That works,
> > but consider the following:
> >
> >        (defvar tmp 'foo)  ;*** the type is in a variable
> >        (with-transaction
> >           (execute-query
> >            (make-query '(select-instances
> >                          (o) (where (typep o tmp)))))))
> >
> > It results in:
> >
> > ; BEGIN
> > ; SELECT _o._oid FROM _foo_ai _o
> > ; COMMIT
> >
> > (so it doesn't select all data, only the OID; the result is a list of
> > objects, but individual SELECT-s will run for each of them to retrieve
> > the value of 's when it's needed).
> >
> > BTW: I'm setting compiled-query-cache like this:
> >
> >   (let ((prc::*compiled-query-cache* (site-query-cache ,site)) ...
> >
> > where site-query-cache is an accessor for the following slot:
> >
> >   (query-cache :accessor site-query-cache
> >                :initform (prc::make-compiled-query-cache))
> >
> > It seems to work, and definitely improves performance (about 2x
> > faster).  Hope it's a clean way...
> >
> > Tomorrow I'll try to understand how to use the macro that Attila
> > suggested--again, sorry for I'm trying to learn too much in too little
> > time...
> >
> > Cheers,
> > -Mihai
> >
> > Levente Mészáros <levente.meszaros at gmail.com> wrote:
> >> I suggest to build a query form dynamically and execute that. Query
> >> cache will prevent calling the query compiler each time and you can
> >> build free queries with this.
> >>
> >> TEST> (defpclass* foo ()
> >>         ((s :type boolean)))
> >> #<PERSISTENT-CLASS FOO>
> >>
> >> TEST> (with-transaction
> >>         (make-instance 'foo :s t))
> >>
> >> ; BEGIN
> >> ; SELECT NEXTVAL('_instance_id')
> >> ; $1 = 475775 as BIGINT, $2 = TRUE as BOOL
> >> ; INSERT INTO _foo (_oid, _s) VALUES ($1::BIGINT, $2::BOOL)
> >> ; COMMIT
> >> #<FOO :persistent #t 7>
> >>
> >> TEST> (with-transaction (execute-query (make-query '(select-instances
> >> (o) (where (typep o 'foo))))))
> >> ; BEGIN
> >> ; SELECT _o._oid, _o._s FROM _foo_ap _o
> >> ; COMMIT
> >> (#<FOO :persistent #t 4> #<FOO :persistent #t 5> #<FOO :persistent #t 6>
> >>  #<FOO :persistent #t 7>)
> >>
> >> Be sure to bind this variable high enough:
> >>
> >> TEST> hu.dwim.perec::*compiled-query-cache*
> >> #<HASH-TABLE :TEST EQUAL :COUNT 2 {10084C4BB1}>
> >>
> >> levy
> >>
> >> --
> >> There's no perfectoin
> >>
> >> On Fri, Oct 9, 2009 at 3:00 PM, Mihai Bazon <mihai at bazon.net> wrote:
> >> > Hi folks,
> >> >
> >> > Here are two variants, I'd say equivalent, to select some objects:
> >> >
> >> >   (select-instances (o) (where (typep o 'db-group)))
> >> >
> >> >   (defvar tmp 'db-user)
> >> >   (select-instances (o) (where (typep o tmp)))
> >> >
> >> > Both work the same, but the first one is better because it results in a
> >> > single select that fetches the data as well.  Here's what I see using
> >> > start-sql-recording:
> >> >
> >> > 1st version:
> >> >
> >> > ; SELECT _o._oid, _o._edition, _o._name, _o._description FROM _db_group_ap _o
> >> >
> >> > 2nd version:
> >> >
> >> > ; SELECT _o._oid FROM _db_group_ai _o
> >> > ; $1 = 69012 as BIGINT
> >> > ; SELECT _edition, _name, _description FROM _db_group_dd WHERE (_oid = $1::BIGINT)
> >> > ; $1 = 134548 as BIGINT
> >> > ; SELECT _edition, _name, _description FROM _db_group_dd WHERE (_oid = $1::BIGINT)
> >> > ; $1 = 200084 as BIGINT
> >> > ; SELECT _edition, _name, _description FROM _db_group_dd WHERE (_oid = $1::BIGINT)
> >> >
> >> > I presume there's some compile-time magic that happens in case 1 and not
> >> > in case 2.  I can't hard-code the type so I'd like to use the second
> >> > variant, but is it possible to optimize it so that it results in a
> >> > single select like the first one?
> >> >
> >> > Thanks for any hints!
> >> > -Mihai
> >> > _______________________________________________
> >> > Cl-perec-devel mailing list
> >> > Cl-perec-devel at common-lisp.net
> >> > http://common-lisp.net/cgi-bin/mailman/listinfo/cl-perec-devel
> >> >
> 
> 
> 
> -- 
> There's no perfectoin