On 10/08/16 10:49, Xu,Wenjian wrote:

Hi all,

MonetDB version: 11.23.7
Ubuntu version: 14.04

I created a new optimizer pipeline by adding an additional optimization step after 'default_pipe', i.e.:
'*my_customized_pipe*'='optimizer.inline();optimizer.candidates();optimizer.remap();optimizer.costModel();optimizer.coercions();optimizer.evaluate();optimizer.pushselect();optimizer.aliases();optimizer.mitosis();optimizer.mergetable();optimizer.deadcode();optimizer.aliases();optimizer.constants();optimizer.commonTerms();optimizer.projectionpath();optimizer.deadcode();optimizer.reorder();optimizer.reduce();optimizer.matpack();optimizer.dataflow();optimizer.querylog();optimizer.multiplex();optimizer.generator();optimizer.profiler();optimizer.garbageCollector();*optimizer.customizedstep()*'

What I have done is:
1) Create an empty optimizer step:
    -- 1.1  add /opt_customizedstep.c/h/ in package /monetdb/optimizer/*/, leave function body /OPTcustomizedstepImplementation() /empty/, /i.e. with one statement */return 0*/
/    -- /1.2 register the step by modifying /opt_wrapper.c /and/optimizer.mal/
2) Add the definition of the new pipeline in /opt_pipes.c/
3) Modify the configuration file to compile the added source files.

After re-build the system, I can enable the new optimizer pipeline by *set optimizer='my_customized_pipe'*. However, I have two issues:

i) using EXPLAIN statement, I found the MAL plan different from the one generated by 'default_pipe' (which should be the same since I did nothing in the added step?). Specifically, the plan seems to be not affected by /optimizer.reorder() /step, i.e.,
bat.new() and bat.append() instructions appear in the end of the plan.

1) make sure you restarted the server.
2) plans are cached, so if you attempt the following
select count(*) from tables
set optimizer='my_customized_pipe'
select count(*) from tables

it still uses the default plan

Furthermore, the optimizer history is not saved unless you
call DEBUG select....

ii) then I entered mdb mode by DEBUG statement. But it seems that some command did not work as before. For example, *optimizer* command does not display actions performed by each optimizer step.

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