How to find if a SELECT is reading from buffer or disk ?

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От Balkrishna Sharma
Тема How to find if a SELECT is reading from buffer or disk ?
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Msg-id BAY149-w19CB46743B9D1EC9D68760F0E80@phx.gbl
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Ответы Re: How to find if a SELECT is reading from buffer or disk ?  ("Kevin Grittner" <Kevin.Grittner@wicourts.gov>)
Re: How to find if a SELECT is reading from buffer or disk ?  (Chirag Dave <cdave@ca.afilias.info>)
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Hi,

I am increasing the shared_buffer size in postgresql.conf and want to measure its effect on READ. In essence I want to know if the SELECT queries I am firing repeatedly is reading from the buffer or going directly to the disk.

I am expecting the first SELECT to go to disk and the subsequent call of the same SELECT to read from buffer .

Right now I am just looking at execution time of the SELECTs and trying to conclude. But there should be a direct way to see where the SELECT reads from.

How can I accomplish this ?

Thanks
Bala


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