Re: pg_stat_wal_write statistics view

On Tue, Feb 7, 2017 at 11:47 AM, Haribabu Kommi
<kommi(dot)haribabu(at)gmail(dot)com> wrote:
> Hi Hackers,
>
> I just want to discuss adding of a new statistics view that provides
> the information of wal writing details as follows
>

+1. I think it will be useful to observe WAL activity.

> postgres=# \d pg_stat_wal_writer
> View "pg_catalog.pg_stat_wal_writer"
> Column | Type | Collation | Nullable |
> Default
> -----------------------+--------------------------+-----------+----------+---------
> num_backend_writes | bigint | |
> |
> num_total_writes | bigint | | |
> num_blocks | bigint | | |
> total_write_time | bigint| | |
> stats_reset | timestamp with time zone | | |
>
> The columns of the view are
> 1. Total number of xlog writes that are called from the backend.
> 2. Total number of xlog writes that are called from both backend
> and background workers. (This column can be changed to just
> display on the background writes).
> 3. The number of the blocks that are written.
> 4. Total write_time of the IO operation it took, this variable data is
> filled only when the track_io_timing GUC is enabled.

So, here is *write_time* the total time system has spent in WAL
writing before the last reset?

I think there should be a separate column for write and sync time.

> Or it is possible to integrate the new columns into the existing
> pg_stat_bgwriter view also.
>

I feel separate view is better.

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com