Re: [Fwd: Index Advisor]

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От Kai-Uwe Sattler
Тема Re: [Fwd: Index Advisor]
Дата
Msg-id 27F0AB56-348F-4C89-B5F4-3F56A498F0EA@tu-ilmenau.de
обсуждение исходный текст
Ответ на Re: [Fwd: Index Advisor]  (Kai-Uwe Sattler <kus@tu-ilmenau.de>)
Ответы Re: [Fwd: Index Advisor]  ("Gurjeet Singh" <singh.gurjeet@gmail.com>)
Список pgsql-hackers
Hi,
Am 15.11.2006 um 15:34 schrieb Gurjeet Singh:
> =====
> .) The SELECTs in the pg_advise are returning wrong results, when  
> the same index is suggested twice, because of the SUM() aggregates.
I don't think that this is a bug. If the same index is recommended  
for two different queries it will appear  two times in  
pg_indexadvisor. So, if you want to calculate the overall benefit of  
this index, then you have to sum up the local benefits for each query.

> .) I doubt that on a table t(a,b), for a suggestion of idx(b,a),  
> pg_advise will
>     suggest idx(a,b);
?? Not sure, if I understand you right. idx(b,a) and idx(a,b) are  
completely different indexes. Why should pg_advise suggest idx(a,b).  
But there is another bug: if there are recommendations like idx 
(a,b,c), idx(a,b) and idx(a) it would be a good idea to create just  
idx(a). I will add this to pg_advise as an optional feature.

Best,    Kai



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