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?

I am using MonetDB 11.21.17 (JUL2015 SP3) and my environment is Ubuntu14.04.

Thank you very much.

Best regards,

XU Wenjian