Re: Online base backup from the hot-standby

>>> I don't much like that approach. The standby would need to be able to
>>> write the backup history file to the archive at the end of backup, and
>>> we'd have to reintroduce the code to fetch it from archive and, when
>>> streaming, from the master. At the moment, the archiver doesn't even run
>>> in the standby.
>>
>> Please teach the reason for "The standby would need to be able to write
>> the backup history file to the archive at the end of backup" .
>> (I'd like to know why "to only pg_xlog" is wrong .)
>
> If the backup history file is not archived, the postgres process won't
> find it when you try to restore from the base backup. The new server has
> no access to the standby's pg_xlog directory.

Thanks for the answer .
But , it sends the backup history file to pg_xlog of new server
(=backup server) when pg_basebackup is executed to the standby server
, and so I was going to create the patch of such logic .
I think it don't become the above-mentioned movement .

>> Because there is the opinion of "Cascade replication" , I don't want to
>> realize the function with the method which the standby requests to execute
>> it on the primary server .
>>
>> (The opinion of "Cascade replication"：
>> http://archives.postgresql.org/pgsql-hackers/2011-05/msg01150.php)
>
>I don't see how this helps.

Hypothesis:
* Online base backup was realized with the method which the standby
requests to execute it on the "primary server" .
* "Cascade replication" was developed , and user is using it .
(Ex. Primary -- Standby1 -- Standby2)

Situation:
(1) Standby2 executes pg_basebackup .
(2) Then, Standby2 accesses Standby1 .
(3) But, it fails, because Standby2's primary is Standby1, not
Primary .

Result:
* I don't want to realize the function with the method which the
standby requests to execute it on the primary server .
--------------------------------------------
Jun Ishizuka
NTT Software Corporation
TEL：045-317-7018
E-Mail: ishizuka(dot)jun(at)po(dot)ntts(dot)co(dot)jp
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