[pgpool-hackers: 2832] Re: Proposal: Add last state change timestamp to "show pool_nodes"

Tatsuo Ishii ishii at sraoss.co.jp
Wed Jun 13 09:36:31 JST 2018


Hi Usama,

In this commit, new function pool_set_backend_status_changed_time() is
added to update the last status change time stamp. However I am not so
sure about the correct timing to call it within watchdog modules. I
would appreciate if you take a look at them in this regard.

Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp

From: Muhammad Usama <m.usama at gmail.com>
Subject: Re: [pgpool-hackers: 2825] Re: Proposal: Add last state change timestamp to "show pool_nodes"
Date: Tue, 12 Jun 2018 18:18:14 +0500
Message-ID: <CAEJvTzXnphb=ZHY9qUenqUOWVGJ2X2dpyk9qHYjon+N4Fckq6w at mail.gmail.com>

> On Tue, Jun 12, 2018 at 5:59 PM Tatsuo Ishii <ishii at sraoss.co.jp> wrote:
> 
>> Ok, I have done. The new column name is "last_status_change" as
>> suggested. However pcp_node_info and pgpool_adm are not updated yet.
>>
>> Many thanks :-)
> 
> Best Regards
> Muhammad Usama
> 
> 
>> Best regards,
>> --
>> Tatsuo Ishii
>> SRA OSS, Inc. Japan
>> English: http://www.sraoss.co.jp/index_en.php
>> Japanese:http://www.sraoss.co.jp
>>
>> > Hi Ishii-San,
>> >
>> > On Tue, Jun 12, 2018 at 5:47 AM Tatsuo Ishii <ishii at sraoss.co.jp> wrote:
>> >
>> >> Hi Usama,
>> >>
>> >> > Hi Ishii-San
>> >> >
>> >> > Thanks for the patch and I totally second the Peng's comment that it
>> is a
>> >> > very useful feature
>> >> > to have and will have many practical use cases.
>> >> > I have couple of small comments on the attached patch
>> >> > One is I think it would be good idea to also include this last status
>> >> > changed column in pcp_node_info's output.
>> >>
>> >> If we do that we need to maintain pgpool_adm as well. Pgpool_adm is
>> >> already far behind from current pcp_node_info implementation since
>> >> pgpool_adm lacks "backend role" column.
>> >>
>> >>
>> > Yes that is one issue, and I believe we need to plan out something for
>> > Pgpool-adm
>> > enhancement to bring it upto Pgpool core version.
>> > I am just thinking Is it possible if  we add the last_status_change
>> column
>> > in pcp_node_info
>> > but Pgpool_adm keep ignoring it until it is updated
>> >
>> >
>> >
>> >> > and secondly what do you think about renaming the "status_changed"
>> column
>> >> > name to "last status change"  in
>> >> > show pool_nodes output?
>> >>
>> >> Maybe but "last status change" is not appropreate column name. It
>> >> should be "last_status_change" or something like that.
>> >>
>> >
>> > Sorry for the type. I actually meant "last_status_change" :-)
>> >
>> > Thanks
>> > Best regards
>> > Muhammad Usama
>> >
>> >>
>> >> > Thanks
>> >> > Best Regards
>> >> > Muhammad Usama
>> >> >
>> >> >
>> >> > On Mon, Jun 11, 2018 at 7:14 PM Tatsuo Ishii <ishii at sraoss.co.jp>
>> wrote:
>> >> >
>> >> >> > Hi Ishii-san,
>> >> >> >
>> >> >> > I think this will be useful to show the last state change
>> timestamp.
>> >> >>
>> >> >
>> >> > Totally agree. This will be a very useful feature to have.
>> >> >
>> >> >>
>> >> >> Thanks. Attached is a patch to implement this. Still documentations
>> >> >> need to be updated.
>> >> >>
>> >> >> > When pgpool-II starts, the timestamp is set to time the startup
>> >> >> > time. After that whenever the status is changed, time timestamp is
>> >> >> > recorded and shown.
>> >> >>
>> >> >> Here "status" means not only "up" and "down" etc. but primary node
>> >> >> changes. For example suppose there are two nodes 0 (primary) and 1
>> >> >> (standby). If node 0 goes down and node 1 is promoted to primary, the
>> >> >> time stamp of node 1 is updated. Though the up/down status of node 1
>> >> >> is not changed (up->up), it becomes primary from standby.
>> >> >>
>> >> >> Here is an example output of "show pool_nodes".
>> >> >>
>> >> >> test=# show pool_nodes;
>> >> >> -[ RECORD 1 ]-----+--------------------
>> >> >> node_id           | 0
>> >> >> hostname          | /tmp
>> >> >> port              | 11002
>> >> >> status            | up
>> >> >> lb_weight         | 0.500000
>> >> >> role              | standby
>> >> >> select_cnt        | 0
>> >> >> load_balance_node | true
>> >> >> replication_delay | 0
>> >> >> status_changed    | 2018-06-11 23:11:45
>> >> >> -[ RECORD 2 ]-----+--------------------
>> >> >> node_id           | 1
>> >> >> hostname          | /tmp
>> >> >> port              | 11003
>> >> >> status            | up
>> >> >> lb_weight         | 0.500000
>> >> >> role              | primary
>> >> >> select_cnt        | 0
>> >> >> load_balance_node | false
>> >> >> replication_delay | 0
>> >> >> status_changed    | 2018-06-11 23:11:45
>> >> >>
>> >> >> Best regards,
>> >> >> --
>> >> >> Tatsuo Ishii
>> >> >> SRA OSS, Inc. Japan
>> >> >> English: http://www.sraoss.co.jp/index_en.php
>> >> >> Japanese:http://www.sraoss.co.jp
>> >> >> _______________________________________________
>> >> >> pgpool-hackers mailing list
>> >> >> pgpool-hackers at pgpool.net
>> >> >> http://www.pgpool.net/mailman/listinfo/pgpool-hackers
>> >> >>
>> >>
>>


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