Re: Automatic function replanning

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От Lukas Smith
Тема Re: Automatic function replanning
Дата
Msg-id 43AB1727.3030902@pooteeweet.org
обсуждение исходный текст
Ответ на Re: Automatic function replanning  (Bruce Momjian <pgman@candle.pha.pa.us>)
Ответы Re: Automatic function replanning  ("Jim C. Nasby" <jnasby@pervasive.com>)
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Bruce Momjian wrote:

> It is an issue for all databases.  We gave a TODO about it:
> 
>     * Flush cached query plans when the dependent objects change,
>       when the cardinality of parameters changes dramatically, or
>       when new ANALYZE statistics are available

Ok, just so I understand this correctly. In the mentioned case the 
cardinality does not really change in regards to the table stats, its 
just thatI happen to use a value that has a different selectivity and 
therefore I may need a different plan. So I do not really see how this 
use case is handled with the above todo, nor do I really see how its 
handled with what Jim suggested earlier. The fact of the matter is that 
for this use case you need to use different query plans for the same 
prepared statements.

regards,
Lukas


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