[pgpool-hackers: 4304] Re: Proposal: Add user_redirect_preference_list

[Tatsuo Ishii]

> Hello,
> 
>> > I would like to add a new GUC parameter "user_redirect_preference_list" to 4.5
>> > to allow routing queries to a specific backend node for a specific user connection.
>> > 
>> > Currently, we have database_redirect_preference_list and app_name_redirect_preference_list,
>> > which allow routing queries to a specific backend node for a specific database connection or
>> > a specific client application connection.
>> > 
>> > I think the use case, which uses a connection user based load balance, is also needed.
>> > 
>> > For example, an application has GUI management console and server daemon,
>> > which connect to the same database. GUI management console mainly issues SELECT
>> > and server daemon mainly issues INSERT.
>> > In such case, users may want to route all queries issued by GUI management console
>> > to standby servers to reduce the load on primary server.
>> > 
>> > To handle such case, normally we can use app_name_redirect_preference_list.
>> > However, in some applications the application name may not be configurable.
>> > 
>> > That is the reason why I want to add this feature.
>> > 
>> > Any comments?
>> 
>> Sounds like a useful feature. However, if it's implemented, now we
>> have
>> database_redirect_preference_list. app_name_redirect_preference_list
>> and user_redirect_preference_list. I feel a little bit redudant. I
>> think we can unify all of them. For example:
>> 
>> redirect_preference_list = 'selector:user,user0:primary,user[1-4]:1,user[5-9]:standby'
>> 
>> where "selector" is one of "user", "app_name" and "database". In the
>> example above, it means that:
>> 
>> - user0 is redirected to primary
>> - user1 to user4 are redirected to db node 1
>> - user5 to user9 are redirected to one of standby servers
>> 
>> What do you think?
> 
> Thank you!
> 
> Yes. I think it is a good idea to unify them.
> 
> If we add this new parameter like "redirect_preference_list",
> I think we should also keep the backward compatibility to make sure
> the old parameters can work with the new major version.

+1.

Best reagards,
--
Tatsuo Ishii
SRA OSS LLC
English: http://www.sraoss.co.jp/index_en/
Japanese:http://www.sraoss.co.jp