[Monetdb-developers] about MAL optimize

kun ren renkun.nwpu at gmail.com
Wed Aug 11 10:23:42 CEST 2010


I read sql_optimizer setting in monetdb5.conf ,and default setting is:
sql_optimizer=default_pipe
default_pipe=inline,remap,evaluate,costModel,coercions,emptySet,aliases,mitosis,mergetable,deadcode,commonTerms,joinPath,reorder,deadcode,reduce,garbageCollector,dataflow,history,multiplex

so there are many optimizer,but why when i debug MonetDB,and dump the mal of
my  sql statement,but i can't find the optimizer mal ,and  don't enter the
optimizer? like there are no optimizer,


2010/8/11 Stefan Manegold <Stefan.Manegold at cwi.nl>

> Yes, if you write MAL "by hand" (or have some program create it) that does
> explicitly call a MAL optimizer, that MAL optimizer is indeed used to
> optimize the MAL code according to its very purpose.
>
> Stefan
>
> On Wed, Aug 11, 2010 at 03:49:47PM +0800, kun ren wrote:
> > It is only used by SQL? and how to designation the optimiser?but when I
> > write MAL,for example,
> > i:=0;
> > b:= "done";
> > barrier go:= true;
> > c:=i+1;
> > d:="step";
> > v:=d;
> > io.print(v);
> > i:=c;
> > redo go:= i<2;
> > exit go;
> > io.print(b);
> > optimizer.aliasRemoval();
> >
> > the last optimizer.aliasRemoval() is used for optimizing?
> >
> > 2010/8/11 Fabian Groffen <Fabian.Groffen at cwi.nl>
> >
> > >  On 11-08-2010 15:25:15 +0800, kun ren wrote:
> > > >    Recently,I am intersting in MAL optimize,and have read the manual
> of
> > > the
> > > > MAL optimize, but it is so long, Possible if we want to use mal
> optimize
> > > ,we
> > > > must  degignation the optimize  consideration,  such as alias
> removal,
> > > > constant expression,join path optimizer;And then I dedug the
> MonetDB,but
> > > > default it don't use any optimize.so what do you think about the mal
> > > > optimize?
> > >
> > > It is only used when you use SQL.  The sql_optimizer setting in
> > > monetdb5.conf controls which optimisers are run, which by default are
> > > quite a few.
> > >
> > >
> > >
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