Re: The way to know whether the standby has caught up with the master - Mailing list pgsql-hackers

From Tom Lane
Subject Re: The way to know whether the standby has caught up with the master
Date
Msg-id 4780.1306332441@sss.pgh.pa.us
Whole thread Raw
In response to Re: The way to know whether the standby has caught up with the master  (Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>)
Responses Re: The way to know whether the standby has caught up with the master  (Fujii Masao <masao.fujii@gmail.com>)
List pgsql-hackers
Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> writes:
> On 25.05.2011 07:42, Fujii Masao wrote:
>> To achieve that, I'm thinking to change walsender so that, when the standby
>> has caught up with the master, it sends back the message indicating that to
>> the standby. And I'm thinking to add new function (or view like
>> pg_stat_replication)
>> available on the standby, which shows that info.

> By the time the standby has received that message, it might not be 
> caught-up anymore because new WAL might've been generated in the master 
> already.

Even assuming that you believe this is a useful capability, there is no
need to change walsender.  It *already* sends the current-end-of-WAL in
every message, which indicates precisely whether the message contains
all of available WAL data.
        regards, tom lane


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