question on backends
Hi all
As I understand every time there is a request to postgres a new backend is made, and when the request is finished, even if the connection is already active the backend dies. I wonder if is there any parameter that allow backends to remain beyond a transaction. Creating a new backend every time a transaction is made means forking the code and reallocating sort_memory. Although it is not a high resource usage, on short transactions as OLTPs it is a relevant work time, I think it would be interesting that a predefined number of backends were allowed to remain active beyond the transaction.
Thanks and Regards
Just use persistent connections.
Chris
----- Original Message -----
From: Luis Alberto Amigo Navarro
To: pgsql-hackers@postgresql.org
Sent: Monday, July 29, 2002 5:32 PM
Subject: [HACKERS] question on backends
Hi all
As I understand every time there is a request to postgres a new backend is made, and when the request is finished, even if the connection is already active the backend dies. I wonder if is there any parameter that allow backends to remain beyond a transaction. Creating a new backend every time a transaction is made means forking the code and reallocating sort_memory. Although it is not a high resource usage, on short transactions as OLTPs it is a relevant work time, I think it would be interesting that a predefined number of backends were allowed to remain active beyond the transaction.
Thanks and Regards
How?
----- Original Message -----
From: Christopher Kings-Lynne
To: Luis Alberto Amigo Navarro ; pgsql-hackers@postgresql.org
Sent: Monday, July 29, 2002 12:36 PM
Subject: Re: [HACKERS] question on backends
Just use persistent connections.
Chris
----- Original Message -----
From: Luis Alberto Amigo Navarro
To: pgsql-hackers@postgresql.org
Sent: Monday, July 29, 2002 5:32 PM
Subject: [HACKERS] question on backends
Hi all
As I understand every time there is a request to postgres a new backend is made, and when the request is finished, even if the connection is already active the backend dies. I wonder if is there any parameter that allow backends to remain beyond a transaction. Creating a new backend every time a transaction is made means forking the code and reallocating sort_memory. Although it is not a high resource usage, on short transactions as OLTPs it is a relevant work time, I think it would be interesting that a predefined number of backends were allowed to remain active beyond the transaction.
Thanks and Regards
libpq has a function pconnect as opposed to connect that will do it. PHP and most other interfaces will let you use persistent connections.
Chris
----- Original Message -----
From: Luis Alberto Amigo Navarro
To: Christopher Kings-Lynne ; pgsql-hackers@postgresql.org
Sent: Monday, July 29, 2002 7:00 PM
Subject: Re: [HACKERS] question on backends
How?
----- Original Message -----
From: Christopher Kings-Lynne
To: Luis Alberto Amigo Navarro ; pgsql-hackers@postgresql.org
Sent: Monday, July 29, 2002 12:36 PM
Subject: Re: [HACKERS] question on backends
Just use persistent connections.
Chris
----- Original Message -----
From: Luis Alberto Amigo Navarro
To: pgsql-hackers@postgresql.org
Sent: Monday, July 29, 2002 5:32 PM
Subject: [HACKERS] question on backends
Hi all
As I understand every time there is a request to postgres a new backend is made, and when the request is finished, even if the connection is already active the backend dies. I wonder if is there any parameter that allow backends to remain beyond a transaction. Creating a new backend every time a transaction is made means forking the code and reallocating sort_memory. Although it is not a high resource usage, on short transactions as OLTPs it is a relevant work time, I think it would be interesting that a predefined number of backends were allowed to remain active beyond the transaction.
Thanks and Regards
On Mon, Jul 29, 2002 at 11:28:54PM +0800, Christopher Kings-Lynne wrote:
libpq has a function pconnect as opposed to connect that will do it.
libpq has neither function, AFAIK.
As for persistent backends, it's on the TODO list, but I'm not aware
that anyone has put any work into implementing it. At the moment,
a backend connects to a single database for its entire lifecycle -- so
you'd either need one pool of persistent backends for each database
in use, or you'd need to allow a backend to change the database it is
connected to.
Cheers,
Neil
--
Neil Conway <neilconway@rogers.com>
PGP Key ID: DB3C29FC
if i put debug_level=1 i get for one connect and several inserts on backend
die after each insert
----- Original Message -----
From: "Hannu Krosing" <hannu@tm.ee>
To: "Luis Alberto Amigo Navarro" <lamigo@atc.unican.es>
Cc: <pgsql-hackers@postgresql.org>
Sent: Monday, July 29, 2002 8:42 PM
Subject: Re: [HACKERS] question on backends
Show quoted text
On Mon, 2002-07-29 at 11:32, Luis Alberto Amigo Navarro wrote:
Hi all
As I understand every time there is a request to postgres a new backend
is made, and when the request is finished, even if the connection is
already active the backend dies.I think you have misunderstood it. A new backend is forked only when a
new connection is made, not for every transaction.There may be some frontends that do make a new connection for each http
request or such, but most of them allow for persistent connections,
either as an option or by default.I wonder if is there any parameter
that allow backends to remain beyond a transaction. Creating a new
backend every time a transaction is made means forking the code and
reallocating sort_memory.------------------
Hannu
On Mon, 2002-07-29 at 11:32, Luis Alberto Amigo Navarro wrote:
Hi all
As I understand every time there is a request to postgres a new backend
is made, and when the request is finished, even if the connection is
already active the backend dies.
I think you have misunderstood it. A new backend is forked only when a
new connection is made, not for every transaction.
There may be some frontends that do make a new connection for each http
request or such, but most of them allow for persistent connections,
either as an option or by default.
I wonder if is there any parameter
that allow backends to remain beyond a transaction. Creating a new
backend every time a transaction is made means forking the code and
reallocating sort_memory.
------------------
Hannu
libpq
PQsetdb(........
----- Original Message -----
From: "Hannu Krosing" <hannu@tm.ee>
To: "Luis Alberto Amigo Navarro" <lamigo@atc.unican.es>
Cc: <pgsql-hackers@postgresql.org>
Sent: Monday, July 29, 2002 9:40 PM
Subject: Re: [HACKERS] question on backends
On Mon, 2002-07-29 at 20:21, Luis Alberto Amigo Navarro wrote:
if i put debug_level=1 i get for one connect and several inserts on
backend
Show quoted text
die after each insert
What client do you use ?
----------
Hannu---------------------------(end of broadcast)---------------------------
TIP 4: Don't 'kill -9' the postmaster
On Mon, 2002-07-29 at 20:21, Luis Alberto Amigo Navarro wrote:
if i put debug_level=1 i get for one connect and several inserts on backend
die after each insert
What client do you use ?
----------
Hannu
On Mon, 2002-07-29 at 20:50, Luis Alberto Amigo Navarro wrote:
libpq
PQsetdb(........
----- Original Message -----
From: "Hannu Krosing" <hannu@tm.ee>
To: "Luis Alberto Amigo Navarro" <lamigo@atc.unican.es>
Cc: <pgsql-hackers@postgresql.org>
Sent: Monday, July 29, 2002 9:40 PM
Subject: Re: [HACKERS] question on backendsOn Mon, 2002-07-29 at 20:21, Luis Alberto Amigo Navarro wrote:
if i put debug_level=1 i get for one connect and several inserts on
backend
die after each insert
It should not happen.
I've run several websites using both php and python (which use libpq to
connect to backend), and they have been up for months connected to the
_same_ backend, doing inserts, updates, deletes and selects.
I guess there is some error in you code that manifests itself as dying
backends.
You can test this by trying to do several inserts in one transaction.
and see if the data is still there after the backend closes after the
first insert.
--------------
Hannu
Ah yes - that was me making an unfortunate exptrapolation without thinking
it through.
Of course, PHP implements persistent connections for you, etc., etc., not
the postgres client library.
Chris
Show quoted text
-----Original Message-----
From: Neil Conway [mailto:nconway@klamath.dyndns.org]
Sent: Tuesday, 30 July 2002 12:11 AM
To: Christopher Kings-Lynne
Cc: Luis Alberto Amigo Navarro; pgsql-hackers@postgresql.org
Subject: Re: [HACKERS] question on backendsOn Mon, Jul 29, 2002 at 11:28:54PM +0800, Christopher Kings-Lynne wrote:
libpq has a function pconnect as opposed to connect that will do it.
libpq has neither function, AFAIK.
As for persistent backends, it's on the TODO list, but I'm not aware
that anyone has put any work into implementing it. At the moment,
a backend connects to a single database for its entire lifecycle -- so
you'd either need one pool of persistent backends for each database
in use, or you'd need to allow a backend to change the database it is
connected to.Cheers,
Neil
--
Neil Conway <neilconway@rogers.com>
PGP Key ID: DB3C29FC