[Monetdb-developers] join performance issue!

Stefan Manegold Stefan.Manegold at cwi.nl
Tue Jul 25 22:24:16 CEST 2006


On Tue, Jul 25, 2006 at 10:02:16PM +0200, Arjen P. de Vries wrote:
> Wasn't the property checking always determined by debug flag 8?

in general: yes.
for join: no, at least not any more since the following checkin:
===================================================================
2003/08/06 - sjoerd: src/gdk/gdk_relop.mx,1.38
DDI Merge.

This is the big one!

Before tag: BeforeDDImerge, after tag: AfterDDImerge.

The DDI merge is now made the official main branch; the CWI_DDI_merge branch
is not to be used anymore.
===================================================================

Well, Sjoerd just did the checking; the origin is most probabaly Peter.
As I said, there are indeed good reasons to do the BATpropcheck (even with
debug=0) for *arbitrary* joins, where we can hardly predict any result
properties --- maybe, we should consider to not do it in those cases
(especially fetchjoin), where we can predict the join result properties
pretty well...

Stefan

> On 25/07/06, Martin Kersten <Martin.Kersten at cwi.nl> wrote:
> >
> >
> >
> >Stefan Manegold wrote:
> >> Dear all,
> >>
> >>
> >> - We should consider making this BATpropcheck in BATjoin and BATleftjoin
> >>   configurable from the outside, e.g., by adding an extra optional
> >argument
> >>   to join() to request to skipping the BATpropcheck.
> >>
> >Instead of pollution of the calling interface, I think we should inject
> >an explicit request to check/enforce properties. This one might also be
> >focussed on those properties of interest according to the optimizer at
> >that point.
> >
> >In M5:
> >   b:= algebra.join(BAT,BAT);
> >   bat.setProperties(b);
> >
> >   ...
> >   bat.checkDenseProperty(b);
> >   bat.checkOrderProperty(b);
> >   bat.checkKeyProperty(b);
> >
> >But first, assess the use of the join(bat,bat) in our controlled
> >code base. Please report on this.
> >
> >regards, Martin
> >
> >
> 
> 
> -- 
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> ===================== http://www.cwi.nl/~arjen/ ====================

-- 
| Dr. Stefan Manegold | mailto:Stefan.Manegold at cwi.nl |
| CWI,  P.O.Box 94079 | http://www.cwi.nl/~manegold/  |
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