Re: Proposal: pg_rewind to skip config files

> 5 сент. 2017 г., в 15:42, Chris Travers <chris(dot)travers(at)adjust(dot)com> написал(а):
>
> On Tue, Sep 5, 2017 at 2:40 PM, Vladimir Borodin <root(at)simply(dot)name <mailto:root(at)simply(dot)name>> wrote:
>
>> 5 сент. 2017 г., в 14:04, Michael Paquier <michael(dot)paquier(at)gmail(dot)com <mailto:michael(dot)paquier(at)gmail(dot)com>> написал(а):
>>
>>> For example, in archive_command we put WALs for archiving from
>>> pg_xlog/pg_wal into another directory inside PGDATA and than another cron
>>> task makes real archiving. This directory ideally should be skipped by
>>> pg_rewind, but it would not be handled by proposed change.
>>
>> I would be curious to follow the reasoning for such a two-phase
>> archiving (You basically want to push it in two places, no? But why
>> not just use pg_receivexlog then?). This is complicated to handle from
>> the point of view of availability and backup reliability + durability.
>
> We do compress WALs and send them over network. Doing it via archive_command in single thread is sometimes slower than new WALs are written under heavy load.
>
> How would this work when it comes to rewinding against a file directory?

Very bad, of course. Sometimes we get 'could not remove file "/var/lib/postgresql/9.6/data/wals/00000001000000C3000000C6": No such file or directory’ while running pg_rewind ($PGDATA/wals is a directory where archive_command copies WALs). That’s why I want to solve the initial problem. Both proposed solutions (using only needed files and skipping files through glob/regex) are fine for me, but not the initial patch.

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