Обсуждение: v7.1 & WAL

The 7.1 Release notes include the statement re WAL below.

"Write-ahead Log (WAL)
To maintain database consistency in case of an operating system crash,
previous releases of PostgreSQL have forced all data modifications to disk
before each transaction commit. With WAL, only one log file must be flushed
to disk, greatly improving performance. If you have been using -F in
previous releases to disable disk flushes, you may want to consider
discontinuing its use."

Have WAL changes had any impact on vacuum?

Are there other benefits gained from these changes? e.g. less likely to see
a corrupted database in the event of a system crash, performance gains, etc?

Where is the new WAL log - pg_log no longer exists?

Thanks for any and all comments.

Peter Schmidt
PRISMedia Networks, Inc.
pschmidt@prismedia.com

> The 7.1 Release notes include the statement re WAL below.
>
> "Write-ahead Log (WAL)
> To maintain database consistency in case of an operating system crash,
> previous releases of PostgreSQL have forced all data modifications to
> disk before each transaction commit. With WAL, only one log file
> must be flushed to disk, greatly improving performance. If you have been
> using -F in previous releases to disable disk flushes, you may want to
> consider discontinuing its use."
>
> Have WAL changes had any impact on vacuum?

No.

> Are there other benefits gained from these changes? e.g. less
> likely to see a corrupted database in the event of a system crash,

Yes (there was posting to -general about non-atomic disk writes).

> performance gains, etc?

Sure, in multi-user environment.

> Where is the new WAL log - pg_log no longer exists?

pg_log still exists. WAL logs are in pg_xlog dir.

Vadim