Re: plan time of MASSIVE partitioning ...

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От Boszormenyi Zoltan
Тема Re: plan time of MASSIVE partitioning ...
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Msg-id 4C87B27B.3010002@cybertec.at
обсуждение исходный текст
Ответ на Re: plan time of MASSIVE partitioning ...  (Stephen Frost <sfrost@snowman.net>)
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Stephen Frost írta:
> * Robert Haas (robertmhaas@gmail.com) wrote:
>   
>> 2010/9/8 Hans-Jürgen Schönig <postgres@cybertec.at>:
>>     
>>> but, it seems the problem we are looking is not sufficiently fixed yet.
>>> in our case we shaved off some 18% of planning time or so - looking at the other top 2 functions i got the feeling
thatmore can be done to reduce this. i guess we have to attack this as well.
 
>>>       
>> Just remember that four small patches (say) are apt to get committed
>> faster than one big one.
>>     
>
> Indeed, but code like this makes me wonder if this is really working the
> way it's supposed to:
>
> +   val1 = (long)pk_left->pk_eclass;
> +   val2 = (long)pk_right->pk_eclass;
> + 
> +   if (val1 < val2)
> +       return -1;
> +   else if (val1 > val2)
> +       return 1;
>   

The original code checked for pointers being equal among
other conditions. This was an (almost) straight conversion
to a comparison function for rbtree. Do you mean casting
the pointer to long? Yes, e.g. on 64-bit Windows it wouldn't
work. Back to plain pointer comparison.

> Have you compared how big the tree gets to the size of the list it's
> supposed to be replacing..?
>   

No, but I think it's obvious. Now we have one TreeCell
where we had one ListCell.

Best regards,
Zoltán Böszörményi

-- 
----------------------------------
Zoltán Böszörményi
Cybertec Schönig & Schönig GmbH
Gröhrmühlgasse 26
A-2700 Wiener Neustadt, Austria
Web: http://www.postgresql-support.de    http://www.postgresql.at/



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