Re: [PATCH] Expose checkpoint timestamp and duration in pg_stat_checkpointer

Hi,

On Fri, Nov 28, 2025 at 10:23:54AM +0530, Soumya S Murali wrote:
> I have updated the code based on the feedback received to my earlier
> mails and prepared a patch for further review.

I think the logging change and the pg_stat_checkpointer changes are
different enough that they should be separate patches. If not just
because the logging change seems to not have had any non-positive
feedback.

> In this patch, I have renamed the checkpoint_total_time to
> last_checkpoint_duration, stats_reset has been kept as the last column
> following the usual pattern, last_checkpoint_duration and
> last_checkpoint_time will now be overwritten per checkpoint and also
> have removed unnecessary lines as per the usual format. I had
> successfully verified the checkpointer duration with different write
> loads and I am attaching the observations for further reference.

I am still not convinced of the usefulness of those changes to
pg_stat_checkpointer, but some feedback on the patch:

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 9217508917..4a45f4f708 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6778,7 +6778,7 @@ LogCheckpointEnd(bool restartpoint, int flags)


/* Store in PendingCheckpointerStats */
- PendingCheckpointerStats.checkpoint_total_time += (double) total_msecs;
+ PendingCheckpointerStats.last_checkpoint_duration = (double) total_msecs;
PendingCheckpointerStats.last_checkpoint_time = CheckpointStats.ckpt_end_t;

[...]

diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index a8eb1f8add..73688041c8 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -263,7 +263,7 @@ typedef struct PgStat_CheckpointerStats
PgStat_Counter sync_time;
PgStat_Counter buffers_written;
PgStat_Counter slru_written;
- PgStat_Counter checkpoint_total_time; /* new: total ms of last checkpoint */
+ PgStat_Counter last_checkpoint_duration; /* new: total ms of last checkpoint */
TimestampTz last_checkpoint_time; /* new: end time of last checkpoint */
TimestampTz stat_reset_timestamp;
} PgStat_CheckpointerStats;

This looks like an incremental patch based on your original one? It is
customary to send the full, updated, patch again.

Michael