Re: Introduce a new view for checkpointer related stats

Hi,

On 2022-11-22 18:08:28 +0530, Bharath Rupireddy wrote:
> diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
> index 2d8104b090..131d949dfb 100644
> --- a/src/backend/catalog/system_views.sql
> +++ b/src/backend/catalog/system_views.sql
> @@ -1105,18 +1105,22 @@ CREATE VIEW pg_stat_archiver AS
>
> CREATE VIEW pg_stat_bgwriter AS
> SELECT
> - pg_stat_get_bgwriter_timed_checkpoints() AS checkpoints_timed,
> - pg_stat_get_bgwriter_requested_checkpoints() AS checkpoints_req,
> - pg_stat_get_checkpoint_write_time() AS checkpoint_write_time,
> - pg_stat_get_checkpoint_sync_time() AS checkpoint_sync_time,
> - pg_stat_get_bgwriter_buf_written_checkpoints() AS buffers_checkpoint,
> pg_stat_get_bgwriter_buf_written_clean() AS buffers_clean,
> pg_stat_get_bgwriter_maxwritten_clean() AS maxwritten_clean,
> - pg_stat_get_buf_written_backend() AS buffers_backend,
> - pg_stat_get_buf_fsync_backend() AS buffers_backend_fsync,
> pg_stat_get_buf_alloc() AS buffers_alloc,
> pg_stat_get_bgwriter_stat_reset_time() AS stats_reset;
>
> +CREATE VIEW pg_stat_checkpointer AS
> + SELECT
> + pg_stat_get_timed_checkpoints() AS checkpoints_timed,
> + pg_stat_get_requested_checkpoints() AS checkpoints_req,
> + pg_stat_get_checkpoint_write_time() AS checkpoint_write_time,
> + pg_stat_get_checkpoint_sync_time() AS checkpoint_sync_time,
> + pg_stat_get_buf_written_checkpoints() AS buffers_checkpoint,
> + pg_stat_get_buf_written_backend() AS buffers_backend,
> + pg_stat_get_buf_fsync_backend() AS buffers_backend_fsync,
> + pg_stat_get_checkpointer_stat_reset_time() AS stats_reset;

I think we should consider deprecating the pg_stat_bgwriter columns but
leaving them in place for a few years. New stuff should only be added to
pg_stat_checkpointer, but we don't need to break old monitoring queries.

Greetings,

Andres Freund