| From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | Jonathan Bartlett <johnnyb(at)eskimo(dot)com> |
| Cc: | holger(at)wizards(dot)de, pgsql-general(at)postgresql(dot)org |
| Subject: | Re: What is WAL used for? |
| Date: | 2003-12-01 21:17:29 |
| Message-ID: | 200312012117.hB1LHT520496@candle.pha.pa.us |
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| Thread: | |
| Lists: | pgsql-general |
Jonathan Bartlett wrote:
> > WAL with ext3's data journaling is quite unnecessary because the WAL
> > sort of IS the database's journal.
>
> I believe you are mistaken. ext3 data journalling only does the
> filesystem. It has no concept of the structure of the database itself.
> WAL is still necessary to keep consistency on the table itself.
What he means is that PostgreSQL doesn't need the file contents restore
pristine on crash recovery, just the directory structure and WAL can
recreate the file contents.
--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
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