accessing intermediate optimizer results.

Martin Kersten martin.kersten at cwi.nl
Fri Apr 1 08:54:10 CEST 2016


On 01/04/16 07:00, Xu,Wenjian wrote:
> Hi all,
>
> I would like to see the intermediate result (i.e., MAL instructions) after each optimizer step in a optimizer pipeline.
>
> So I searched Monetdb's documents and found the following sentence in https://www.monetdb.org/Documentation/Cookbooks/SQLrecipes/OptimizerPipelines:
>
> "Alternatively, the SQL DEBUG statement modifier in combination with the 'o' command provides access to the intermediate optimizer results."
>
> I cannot figure out what this sentence means.
> What I know about SQL DEBUG statement is to use "debug <SQL statement>" to enter the debug mode and iterate through each (final) MAL instruction one by one.
> How could I use 'o' command to access intermediate optimizer results?

if you step iterate through the plan in MAL debugger you have several commands at your disposal.
For this type 'help'. One of the options is 'optimizer' or abreviated with 'o', which shows you
the optimizer steps.
Using the modified 'list' command, you can access each intermediate, e.g. 'list[3]' to illustrate
the plan after the 3rd optimizer step.

regards, Martin
>
> I am using MonetDB 11.21.17 (JUL2015 SP3) and my environment is Ubuntu14.04.
>
> Thank you very much.
>
> Best regards,
> XU Wenjian
>
>
>
>
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