[pgpool-general: 610] Re: About configuration parameters

Sat Jun 9 04:38:04 JST 2012

Ok, thank you very much for your help. 

Regards. 

----- Mensaje original -----

> > Very good this explanation, at this moment I can understand this
> > process very well.
> >
> > Now, if num_init_children = 2 and max_pool = 2, it seems that for
> > each child process could have 2 cached connections. But, if there
> > are 2 clients connected to pgpool at the same time, and a third
> > client tries to connect to pgpool and there are cached
> > connections. Why this connection should be queued if the
> > parameters of the conection like user and database are cached. If
> > I am wrong the answer are welcom.

> Because those two child process are busy for #5. Until some of them
> reaches #0, new connection requests are queued.
> --
> Tatsuo Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese: http://www.sraoss.co.jp

> > Thank you very much for your answer, time and patience.
> >
> > Regards.
> >
> > ----- Mensaje original -----
> >
> >
> > No, we frequently have had similar questions from people and I
> > think
> > the doc surely has a room to enhance. So please don't hesitate to
> > propose enhancement of the doc if you have a good idea.
> >
> > Regarding your question, a short answer is no, but I think it's
> > better
> > to explain what actually happens inside pgpool:
> >
> > 0) Wait for connection request from clients.
> >
> > 1) pgpool child receives connection request from a client.
> >
> > 2) The pgpool child looks for existing connection in the pool which
> > has requested database/user pair
> >
> > 3) If found, reuse it.
> >
> > 4) If not found, opens a new connection to PostgreSQL and registers
> > to
> > the pool. If the pool has no empty slot, closes the oldest
> > connection to PostgreSQL and reuse the slot.
> >
> > 5) Do some query processing until the client sends session close
> > request.
> >
> > 6) Close the connection to client but keeps the connection to
> > PostgreSQL for future use.
> >
> > 7) Go to #0
> > --
> > Tatsuo Ishii
> > SRA OSS, Inc. Japan
> > English: http://www.sraoss.co.jp/index_en.php
> > Japanese: http://www.sraoss.co.jp
> >
> >> Tatsuo, sorry for my questions. It is not my intention to
> >> criticize the documentation because I think the documentation of
> >> pgpool-II is very good. I just write you because I need
> >> understand some things that I do not know. Maybe my questions are
> >> not writen in a good way.
> >>
> >> When max_pool has a value such as 4. It means that the same child
> >> process can be opened 4 connections regardless of the connections
> >> that can be reused?
> >>
> >> Thank you very much for your time.
> >>
> >> Regards.
> >>
> >> ----- Mensaje original -----
> >>
> >>
> >>> 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
> >>>
> >>>
> >>> 10mo. ANIVERSARIO DE LA CREACION DE LA UNIVERSIDAD DE LAS
> >>> CIENCIAS INFORMATICAS...
> >>> CONECTADOS AL FUTURO, CONECTADOS A LA REVOLUCION
> >>>
> >>> http://www.uci.cu
> >>> http://www.facebook.com/universidad.uci
> >>> http://www.flickr.com/photos/universidad_uci
> >>
> >> 10mo. ANIVERSARIO DE LA CREACION DE LA UNIVERSIDAD DE LAS CIENCIAS
> >> INFORMATICAS...
> >> CONECTADOS AL FUTURO, CONECTADOS A LA REVOLUCION
> >>
> >> http://www.uci.cu
> >> http://www.facebook.com/universidad.uci
> >> http://www.flickr.com/photos/universidad_uci
> >>
> >>
> >>
> >>
> >>
> >> 10mo. ANIVERSARIO DE LA CREACION DE LA UNIVERSIDAD DE LAS CIENCIAS
> >> INFORMATICAS...
> >> CONECTADOS AL FUTURO, CONECTADOS A LA REVOLUCION
> >>
> >> http://www.uci.cu
> >> http://www.facebook.com/universidad.uci
> >> http://www.flickr.com/photos/universidad_uci
> >
> > 10mo. ANIVERSARIO DE LA CREACION DE LA UNIVERSIDAD DE LAS CIENCIAS
> > INFORMATICAS...
> > CONECTADOS AL FUTURO, CONECTADOS A LA REVOLUCION
> >
> > http://www.uci.cu
> > http://www.facebook.com/universidad.uci
> > http://www.flickr.com/photos/universidad_uci
> >
> >
> >
> >
> >
> > 10mo. ANIVERSARIO DE LA CREACION DE LA UNIVERSIDAD DE LAS CIENCIAS
> > INFORMATICAS...
> > CONECTADOS AL FUTURO, CONECTADOS A LA REVOLUCION
> >
> > http://www.uci.cu
> > http://www.facebook.com/universidad.uci
> > http://www.flickr.com/photos/universidad_uci

> 10mo. ANIVERSARIO DE LA CREACION DE LA UNIVERSIDAD DE LAS CIENCIAS
> INFORMATICAS...
> CONECTADOS AL FUTURO, CONECTADOS A LA REVOLUCION

> http://www.uci.cu
> http://www.facebook.com/universidad.uci
> http://www.flickr.com/photos/universidad_uci

10mo. ANIVERSARIO DE LA CREACION DE LA UNIVERSIDAD DE LAS CIENCIAS INFORMATICAS...
CONECTADOS AL FUTURO, CONECTADOS A LA REVOLUCION

http://www.uci.cu
http://www.facebook.com/universidad.uci
http://www.flickr.com/photos/universidad_uci
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