Query planning read a large amount of buffers for partitioned tables

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