Re: Max number of WAL files in pg_xlog directory for Postgres 9.2 version
| От | Raghavendra Rao J S V |
|---|---|
| Тема | Re: Max number of WAL files in pg_xlog directory for Postgres 9.2 version |
| Дата | |
| Msg-id | CAEHH7R4K_g+Pxo-jxe5tZ7_j3UycE9tD-ke3FgAV5+Pt_jkq1w@mail.gmail.com обсуждение исходный текст |
| Ответ на | RE: Max number of WAL files in pg_xlog directory for Postgres 9.2version (Johnes Castro <johnescm@hotmail.com>) |
| Список | pgsql-general |
Hi John,
As you said, I have gone through the document. Which one is correct [(2 + checkpoint_completion_target) * checkpoint_segments + 1 or checkpoint_segments + wal_keep_segments + 1 files] for 9.2 PostgreSQL?
In my environment we have kept wal_keep_segments and checkpoint_segments as below. Will it cause any negative impact?
checkpoint_segments = 128 # in logfile segments, min 1, 16MB each
#checkpoint_timeout = 5min # range 30s-1h
#checkpoint_completion_target = 0.5 # checkpoint target duration, 0.0 - 1.0
#checkpoint_warning = 30s # 0 disables
#wal_keep_segments = 0 # in logfile segments, 16MB each; 0 disables
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
There will always be at least one WAL segment file, and will normally not be more than (2 + checkpoint_completion_target) * checkpoint_segments + 1 or checkpoint_segments + wal_keep_segments + 1 files. Each segment file is normally 16 MB (though this size can be altered when building the server). You can use this to estimate space requirements for WAL. Ordinarily, when old log segment files are no longer needed, they are recycled (renamed to become the next segments in the numbered sequence). If, due to a short-term peak of log output rate, there are more than 3 * checkpoint_segments + 1 segment files, the unneeded segment files will be deleted instead of recycled until the system gets back under this limit.
Regards,
Raghavendra Rao
On Wed, 5 Sep 2018 at 23:23, Johnes Castro <johnescm@hotmail.com> wrote:
1 wal by default occupies 16MB.
The parameter in version 9.2 that controls this is: wal_keep_segments
By setting the parameter to 10, the maximum size of the US pg_xlog will be 160MB.Best Regards,Johnes CastroDe: Johnes Castro <johnescm@hotmail.com>
Enviado: quarta-feira, 5 de setembro de 2018 15:48
Para: Raghavendra Rao J S V; pgsql-general@lists.postgresql.org
Assunto: RE: Max number of WAL files in pg_xlog directory for Postgres 9.2 versionHi,This page in the documentation can help you.https://www.postgresql.org/docs/9.2/static/wal-configuration.htmlBest Regards,Johnes Castro
Enviado: quarta-feira, 5 de setembro de 2018 15:39
Para: pgsql-general@lists.postgresql.org
Assunto: Max number of WAL files in pg_xlog directory for Postgres 9.2 versionHi All,We are using postgres 9.2 verstion database.Please let me know, how many max number of wal files in pg_xlog directory?What is the formul. I am seeing different formulas. Could you provide me which decides number of max WAL files in PG_XLOG directory for Postgres 9.2 Database,please?--Regards,
Raghavendra Rao J S V
Regards,
Raghavendra Rao J S V
Mobile- 8861161425
Raghavendra Rao J S V
Mobile- 8861161425
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Сообщение: Is there any impact if "#wal_keep_segments = 0 " and"checkpoint_segments = 128" postgresql.conf file.