RE: WAL archive (archive_mode = always) ?
От | Tsunakawa, Takayuki |
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Тема | RE: WAL archive (archive_mode = always) ? |
Дата | |
Msg-id | 0A3221C70F24FB45833433255569204D1FAE5C91@G01JPEXMBYT05 обсуждение исходный текст |
Ответ на | Re: WAL archive (archive_mode = always) ? (Narayanan V <vnarayanan.email@gmail.com>) |
Список | pgsql-hackers |
From: Narayanan V [mailto:vnarayanan.email@gmail.com] > I think what Takayuki is trying to say is that streaming replication works > by sending the contents of the WAL archives to the standbys. If archive_mode > was NOT set to always, and if you wanted to archive WAL logs in the standby > you would need to rely on the process_command and make it ship the WAL logs > (to the standby). This causes the same WAL log information to be shipped > in two places, > > 1. Through Streaming Replication > 2. By the process_command > > This redundant shipping of the same information is expensive and consumes > network bandwidth. This can be avoided with the use of archive_mode=always. > > archive_mode=always makes the standby archive the WAL logs it receives, > thus avoiding the requirement of having to ship it separately. Exactly. (archive_command, not process_command) Thanks, Narayanan. Regards Takayuki Tsunakawa
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