[Monetdb-developers] regarding debug output in query execution

Stefan Manegold Stefan.Manegold at cwi.nl
Mon Apr 12 16:55:17 CEST 2010

On Sun, Apr 11, 2010 at 02:55:55AM +0530, anshul gangwar wrote:
> hello   Is there a cluster(column consists of many clusters) based joining. If so than is there different algo used for each cluster also. 

No. In the current open source codebase of MonetDB, all joins are
"monolithic" over the whole BAT (column).

> What is the difference between (b=tmp_2607) and b=tmpr_2610 

First, the "tmp" prefix indicates that both are unname (probably
transient, i.e., non-persistent BATs).
Second, the different IDs indicate that this are different BATs.
Third, the "r" in "tmpr_" indicates that this is a reversed view of a BAT,
i.e., with head and tail logically swapped.

> Is there any big differece between them.

Probably yes, given that they are different BATs.

> And any time real BAT ids of (id given at time of creation) columns are passed to BAT_fetchjoin i.e algos or the bat id passed are only of the clusters.

I'm not sure I completely understand what you're asking,
but as said before, joins work on the whole input BAT(s).

> In which file we can find the code where mil code(generated physical plan from pf) code given as input and algo finding process starts

This depends on how you run your XQuery, i.e., via
	mclient -lxquery
	pf | mclient -lmil
	pf | Mserver

but "eventually" the MIL plan is interpreted by the MIL interpreter in 
MonetDB4/src/monet/monet_interpreter.mx, which basically calls for each MIL
statement the C function that implements it.


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| Dr. Stefan Manegold | mailto:Stefan.Manegold at cwi.nl |
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