Query planning read a large amount of buffers for partitioned tables - Mailing list pgsql-performance

From bruno vieira da silva
Subject Query planning read a large amount of buffers for partitioned tables
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Msg-id CAB+Nuk9NAH8MxDK9ng9G+Vvs8XAaaV7Jc=F7FWrbF8U8WWaDEw@mail.gmail.com
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Responses Re: Query planning read a large amount of buffers for partitioned tables
Re: Query planning read a large amount of buffers for partitioned tables
List pgsql-performance
Hello All. 

On pg 17 now we have better visibility on the I/O required during query planning. 
so, as part of an ongoing design work for table partitioning I was analyzing the performance implications of having more or less partitions.
In one of my tests of a table with 200 partitions using explain showed a large amount of buffers read during planning. around 12k buffers.

I observed that query planning seems to have a caching mechanism as subsequent similar queries require only a fraction of buffers read during query planning.
However, this "caching" seems to be per session as if I end the client session and I reconnect the same query execution will require again to read 12k buffer for query planning.

Does pg have any mechanism to mitigate this issue ( new sessions need to read a large amount of buffers for query planning) ? or should I mitigate this issue by the use of connection pooling. 
How is this caching done? Is there a way to have viability on its usage? Where is it stored?

Thanks
--
Bruno Vieira da Silva

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