[Monetdb-developers] final execution plan

Stefan Manegold Stefan.Manegold at cwi.nl
Thu Mar 11 10:35:35 CET 2010


On Thu, Mar 11, 2010 at 11:13:20AM +0530, Puneet Birwa wrote:
> hello,
>          can anyone tell me how in monetdb/xquery we can see what is the final plan with the help of which query is executed i.e how can i find the plan generated at run time for query execution (which tells that which join operation is performed at particular node).

you can use 'pf', the stand-alone version of the Pathfinder XQuery compiler
to see the generated MIL plan.
See
	`pf --help`
and
	`pf --fullhelp`
for details.

Except from choosing algorithms and implementations based on the properties
of operators' actual input(s) at runtime, the physical algebra plan (MIL
program) is executed as is.

Choosing the algorithms and implementations is done inside the operators'
implementations (see e.g., the code in MonetDB/src/gdk/relop.(mx|c)), and
can only be traced by single-stepping the execution in a debugger or by
enabling debugging output via the Mserver commandline option
	--debug=2097152

(see MonetDB4/conf/MonetDB.conf[.in] or <fix>/etc/MonetDB.conf for all
available debug options.)

Stefan

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