[Pgpool-hackers] Admin interface, statistics views, etc

[Guillaume Lelarge]

Le 19/07/2010 04:53, Tatsuo Ishii a écrit :
>> I've been thinking about the new release. I've always wanted to add
>> something in pgAdmin that could discover the "pgpool" server. There are
>> two ways to do it: with a "SHOW pool_status", and with the
>> inet_server_addr() stored function. There should be a third in 9.1 with
>> the pg_stat_get_backend_server_port() stored function.
>>
>> I would like to see two kinds of informations: configuration (which we
>> already have with the "SHOW pool_status" statement), and statistics
>> (which, AFAICT, aren't available). It would be great to have something
>> like pg_stat_activity but at the pgpool level. I mean, the
>> pg_stat_activity stat view only display the IP address of the pgpool
>> server. So, it would be great to know where the real client is.
>> Something like:
>>
>> SELECT * FROM pool_stat_activity;
>>
>> -[ RECORD 1 ]----+--------------------------------
>> pool_pid         |
>> pool_id          |
>> pool_start       |
>> pgsql_hostname   | 127.0.0.1
>> pgsql_port       | 5432
>> pgsql_pid        |
>> working          | f
>>
>> pool_pid would be the PID of the pgPool child connected to the real
>> client. pool_id would by the pool number (connectionid could be a better
>> name). pool_start would be the timestamp wrt to the start of pgPool
>> child process. pgsql_hostname, pgsql_port would identify the PostgreSQL
>> server it is connected to. pgsql_pid would be the PID of the postgres
>> backend process (this information would help to cross the information
>> with pg_stat_activity). working would be a boolean value telling which
>> pool_id is really working at the moment.
>>
>> There could be other interesting informations as the list of servers
>> (pool_stat_servers) which could tell us how many servers are available,
>> which one are really available, how many queries were executed on each, etc.
>>
>> Seems it would be a great project to add to the 3.0 release, don't you
>> think?
>>
>> Other comments?
> 
> It seems like infomation you want is almost there if you use
> pcp_proc_count and pcp_proc_info:
> $ pcp_proc_count 10 localhost 9898 postgres hogehoge
> 3815
> 
> $ pcp_proc_info 10 localhost 9898 postgres hogehoge 3815
> postgres_db postgres 1150769932 1150767351 3 0 1
> 
> The result is in the following order:
> 1. connected database name
> 2. connected username
> 3. process start-up timestamp
> 4. connection created timestamp
> 5. protocol major version
> 6. protocol minor version
> 7. connection-reuse counter
> 
> So only missing data is pgsql_pid.  (pgsql_hostname and pgsql_port can
> be obtained from pool_status)
> 
> I'm looking forward to add pgsql_pid to pcp_proc_info. What do you
> think?

Could be interesting, but not in my case. I want to make this kind of
information available in pgAdmin. And I don't see how I can have that
with the pcp_* commands. I can grab the code of the pcp_* commands, but
I will need to make another connection to something quite different from
a PostgreSQL database. And nothing garanties that it will work the same
in other releases. Does the language between pgpool and pcp change
between release? I suppose so, but probably not to make them
incompatible? If it feels like it would be compatible, that's something
I can try, yes.


-- 
Guillaume
 http://www.postgresql.fr
 http://dalibo.com