[pgpool-hackers: 661] Re: Review: pgpool-II 3.5 road map

[Ahsan Hadi]

Thanks Tatsuo for your feedback. Please see my response in-line..

On Wed, Nov 12, 2014 at 10:22 AM, Tatsuo Ishii <ishii at postgresql.org> wrote:

> Ahasan,
>
> I have reviewed you proposal of 9.5 road map (#8, #9 #10 are my
>

Do you mean 3.5 road map?


> additions).  It seems #4, #8, #10 are feasible. I think others need to
> be studied or elaborated more.
>

Are you proposing 4,8,10 for pgpool 3.5? I don't think this would be enough
from a feature perspective for a major pgpool release, we need to include a
feature or two form the performance or HA type of features.

You are right we need RND on some of the important items however i feel
that we should start that RND work in the current team if no one else picks
it up.


>
> 1)  performance issue with prepared protocol.
>     - testing pgpool for query latency and find out where we can make
> improvement.
>
>     This is already on the TODO list for years now but nobody comes up
>     with an idea to implement it. I think we will wait for someone
>     thinks of nice idea.
>

Yeah this is very important, we should really get someone to look at this
for 3.5.  The testing of query latency will also give ideas for other
performance improvements.


>
> 2) Next steps for HA...Is there a way to provide automatic and
>    seamless failover for active sessions.
>
>    I have no idea how to implement it. Suppose failover happens while
>    client is receiving SELECT result data from pgpool-II. We need to
>    find a way to remember what data has been already sent and not to
>    switch to different backend and to continue the session.
>
>
I believe Usama is planning to do some RND on watchdog soon. He will study
the techniques and architecture used by cloud and other systems for HA and
propose some enhancements that we can implement for watchdog in pgpool II.


> 3) multi master communication. two independent pairs of pgpool needed
>    to communicate.
>
>    Can you please elaborate what needed for pgpool-II? Sounds vague to me.
>

Yeah i agree the requirements is a bit vague. Basically we had a customer
who was running two pairs of pgpool in two different countries. He wanted
to have some sort of multi master communication between the pairs so if a
node goes down in one pair, a message is sent to other pair. The clients
connecting to one pair

Usama, Can you give some further clarifications on this since you also
looked into the customer query...

Here is the snippet form the user's email :

As you know, we have a pair of PG-Pool boxes in both of our 2 sites.

Each pair uses watchdog to communicate and to manage the VIP. Each
pair is configured
to
use all 4 of the back-end DBs ­ 2 in each site. I have set LB weighting so
that
the queries are sent to the local DBs in the vast majority of cases.

What I think we need to do is make the 2 pairs of PG-Pool communicate so
that
if a node is detached at one side, this info is passed through to the other
PG-Pool pair. I have tried to setup watchdog between all 4 of the PG-Pool
boxes
and although I can see that the additional WD packets are being sent
they don¹t seem to be processed at the far end.



>
> 4) parser integration with latest pg version
>
>    Yes, we should integrate PostgreSQL 9.5's parser for pgpool-II 3.5.
>
>
> 5) Ability to re-issue queries when it failover to the stand-by node.
>    Currently the user has re-issue queries
>
>    Looks identical to #2.
>

Hmm...I believe 2 is about doing a seamless failover for active sessions...

This one came from Bruce...

Bruce, do you think 5 and 2 are identical?


> 6) Would like to see pgpool in separate sub modules that can be
>    installed separately for each feature, along with a common-libs
>    sub-package or so.
>
>    I have no idea what this actually means. We will wait until someone
>    comes up with more concrete idea.
>
> 7) Adding transaction based pooling to pgpool
>
>    Probably we should try pgbouncer + pgpool-II combo first to see if
>    it's actually useful.
>
> 8) Enhance pcp commands
>
>    http://pgpool.net/mediawiki/index.php/TODO#Enhance_pcp_commands
>
> 9) create separate process for health checking
>
>
> http://pgpool.net/mediawiki/index.php/TODO#Create_separate_process_for_health_checking
>
> 10) Create yum repository
>
> Best regards,
> --
> Tarts Ishii
> SRA OSS, Inc. Japan
> English: http://www.sraoss.co.jp/index_en.php
> Japanese:http://www.sraoss.co.jp
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>



-- 
Ahsan Hadi
Snr Director Product Development
EnterpriseDB Corporation
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