On 2008-02-07 18:45, Romulo Goncalves wrote:
> Update of /cvsroot/monetdb/MonetDB5/src/optimizer
> In directory sc8-pr-cvs16.sourceforge.net:/tmp/cvs-serv22937
>
> Modified Files:
> opt_joinpath.mx
> Log Message:
> Revert Martin code because it does not work. The code will remain, but
> commented
> for future improvements as Martin suggested...
A better way to comment larger sections of code is to use #if 0/#endif.
That nests.
>
>
>
> Index: opt_joinpath.mx
> ===================================================================
> RCS file: /cvsroot/monetdb/MonetDB5/src/optimizer/opt_joinpath.mx,v
> retrieving revision 1.21
> retrieving revision 1.22
> diff -u -d -r1.21 -r1.22
> --- opt_joinpath.mx 7 Feb 2008 16:57:18 -0000 1.21
> +++ opt_joinpath.mx 7 Feb 2008 17:44:59 -0000 1.22
> @@ -231,22 +231,30 @@
> The join path optimizer takes a join sequence and
> attempts to minimize the intermediate result.
> The choice depends on a good estimate of intermediate
> -results.SAMPLE_THRESHOLD_lOG
> +results.
> For the time being, we use a simplistic model, based
> on the assumption that most joins are foreign key joins anyway.
> +
> We use a sample based approach for sizeable tables.
> -The model is derived from the select statement.
> +The model is derived from the select statement. However, we did not succeed.
> +The code is now commented for future improvement.
> +Final conclusion from this exercise is:
> +The difference between the join input size and the join output size is not
> +the correct (or unique) metric which should be used to decide which order
> +should be used in the joinPath.
> +
> @c
> -#define SAMPLE_THRESHOLD_lOG 17
> +/*#define SAMPLE_THRESHOLD_lOG 17*/
> size_t
> ALGjoinCost(BAT *l, BAT *r)
> {
> - size_t lc, rc, lsize,rsize;
> - BAT *lsample, *rsample, *j;
> + size_t lc, rc;
> +/* size_t lsize,rsize;
> + BAT *lsample, *rsample, *j; */
>
> lc = BATcount(l);
> rc = BATcount(r);
> - if( lc > 100000 || rc > 100000){
> +/* if( lc > 100000 || rc > 100000){
> lsize= MIN(lc/100, (1<<SAMPLE_THRESHOLD_lOG)/3);
> lsample= BATsample(l,lsize);
> BBPreclaim(lsample);
> @@ -257,7 +265,7 @@
> lsize= BATcount(j);
> BBPreclaim(j);
> return lsize;
> - }
> + }*/
> if( l->ttype== TYPE_oid || r->htype== TYPE_oid )
> return MIN(lc,rc);
> return lc * rc;
>
>
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--
Sjoerd Mullender
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