[pgpool-general: 599] Re: About configuration parameters
Tatsuo Ishii
ishii at postgresql.org
Wed Jun 6 08:23:46 JST 2012
> Hello everyone in the list. In other mails I asked about this topic, but I have some doubt with this configuration parameters. As I know, connection pooling software like pgpool-II, has a number of connections opened and reuses them whenever a new connection with the same properties comes in.
>
> About these configuration parameters:
>
> max_connections: Is the maximum concurrent connections between clients and postgresql server. (postgresql property)
>
> num_init_children: Like max_connections, it is the maximum concurrent connections between clients and pgpool-II. (pgpool property)
>
> max_pool: The maximum number of cached connections in pgpool-II children processes. pgpool-II reuses the cached connection if an incoming connection is connecting to the same database with the same username. If not, pgpool-II creates a new connection to the backend. If the number of cached connections exceeds max_pool, the oldest connection will be discarded, and uses that slot for the new connection. (According pgpool-II documentation)
>
>
> 1. Why max_connexion must satisfy this formula max_connexion >= (Nun_init_children * max_pool) and not this max_connexion >= nun_init_children?
>
> 2. A child process only opens one connection in the database server and it can be use concurrently (max_pool), or for each child process, it open a total of max_pool connections in the database server?
>
> 3. When is possible that the number of cached connections exceeds max_pool?
Have you read this section in the pgpool doc? If yes and still have
questions please clarify. I would love to hear from you to enhance our
document.
<dt><a name="MAX_POOL"></a>max_pool</dt>
<dd>
<p>The maximum number of cached connections in pgpool-II children processes.
pgpool-II reuses the cached connection if an incoming connection is
connecting to the same database with the same username.
If not, pgpool-II creates a new connection to the backend.
If the number of cached connections exceeds max_pool,
the oldest connection will be discarded, and uses that slot for the new connection.
> The answers about these questions are welcome.
> Thank you very much for your time and sorry for such insistence.
> Regards
>
>
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