Re: TODO : Allow parallel cores to be used by vacuumdb [ WIP ]

Dilip kumar wrote:

> Changes:
> 1. In current patch vacuum_one_database (for table list), have the table loop outside and analyze_stage loop inside,
soit will finish
 
> All three stage for one table first and then pick the next table. But vacuum_one_database_parallel will do the stage
loopoutside and will call run_parallel_vacuum,
 
> Which will have table loop, so for one stage all the tables will be vacuumed first, then go to next stage.
> So for merging two function both functions behaviors should be identical, I think if user have given a list of tables
inanalyze-in-stages, than doing all the table
 
> Atleast for one stage and then picking next stage will be better solution so I have done it that way.

Yeah, I think the stages loop should be outermost, as discussed upthread
somewhere -- it's better to have initial stats for all tables as soon as
possible, and improve them later, than have some tables/dbs with no
stats for a longer period while full stats are computed for some
specific tables/database.

I'm tweaking your v24 a bit more now, thanks -- main change is to make
vacuum_one_database be called only to run one analyze stage, so it never
iterates for each stage; callers must iterate calling it multiple times
in those cases.  (There's only one callsite that needs changing anyway.)

> 2. in select_loop
> For WIN32 TranslateSocketError function I replaced with
>                         if (WSAGetLastError() == WSAEINTR)
>                                 errno == EINTR;
> 
> otherwise I have to expose TranslateSocketError function from socket and include extra header.

Grumble.  Don't like this bit, but moving TranslateSocketError to
src/common is outside the scope of this patch, so okay.  (pg_dump's
parallel stuff has the same issue anyway.)

In case you're up for doing some more work later on, there are two ideas
here: move the backend's TranslateSocketError to src/common, and try to
merge pg_dump's select_loop function with the one in this new code.  But
that's for another patch anyway (and this new function needs a little
battle-testing, of course.)

> I have tested in windows also its working fine.

Great, thanks.

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Álvaro Herrera                http://www.2ndQuadrant.com/
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