Confused about the buffer pool size - Mailing list pgsql-hackers

From MMK
Subject Confused about the buffer pool size
Date
Msg-id 375913.43189.qm@web35502.mail.mud.yahoo.com
Whole thread Raw
In response to Re: Synchronization levels in SR  (Simon Riggs <simon@2ndQuadrant.com>)
Responses Re: Confused about the buffer pool size
List pgsql-hackers
Hello All:

In the code (costsize.c), I see that effective_cache_size is set to DEFAULT_EFFECTIVE_CACHE_SIZE.

This is defined as follows in cost.h

#define DEFAULT_EFFECTIVE_CACHE_SIZE 16384

But when I say 

show shared_buffers in psql I get,

shared_buffers 
----------------
 28MB

In postgresql.conf file, the following lines appear

shared_buffers = 28MB                   # min 128kB
           # (change requires restart)
#temp_buffers = 8MB                     # min 800kB


So I am assuming that the buffer pool size is 28MB = 28 * 128 = 3584 8K pages.

So should effective_cache_size be set to 3584 rather than the 16384?

Thanks,

MMK.












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