Re: max_connections proposal - Mailing list pgsql-general

From Edison So
Subject Re: max_connections proposal
Date
Msg-id BANLkTikYXp4PH36d9ESYhPmnwcFPcwcR_A@mail.gmail.com
Whole thread Raw
In response to max_connections proposal  (Craig Ringer <craig@postnewspapers.com.au>)
Responses Re: max_connections proposal
List pgsql-general
Can anyone tell me that if the max_connections is above 100, the server will use pooling instead?
 
For all participants in this particular dsicuss, what is the reasonable value for max_connections without causing any harm to the Postgres 9.0 server.
 
I am a nonvice Postgres user so any advice is always welcomed.
 
Thanks,

On Wed, May 25, 2011 at 10:58 PM, Craig Ringer <craig@postnewspapers.com.au> wrote:
There might be a very cheap and simple way to help reduce the number of people running into problems because they set massive max_connections values that their server cannot cope with instead of using pooling.

In the default postgresql.conf, change:

max_connections = 100                   # (change requires restart)
# Note:  Increasing max_connections costs ~400 bytes of shared memory
# per connection slot, plus lock space (see max_locks_per_transaction).

to:

max_connections = 100                   # (change requires restart)
# WARNING: If you're about to increase max_connections above 100, you
# should probably be using a connection pool instead. See:
#     http://wiki.postgresql.org/max_connections
#
# Note:  Increasing max_connections costs ~400 bytes of shared memory
# per connection slot, plus lock space (see max_locks_per_transaction).
#


... where wiki.postgresql.org/max_connections (which doesn't yet exist) explains the throughput costs of too many backends and the advantages of configuring a connection pool instead.

Sure, this somewhat contravenes the "users don't read - ever" principle, but we can hope that _some_ people will read a comment immediately beside the directive they're modifying.

--
Craig Ringer

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Edison

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