Thread

1. Re: log_checkpoints: count WAL segment creations from all processes

   Hüseyin Demir <huseyin.d3r@gmail.com> — 2026-05-16T17:22:35Z

   Hi,
   
   Thanks for the patch. The idea is good and can we introduce a new
   counter to pg_stat_checkpointer ? For example, we can add
   wal_segments_created to this view and it would be useful for capacity
   planning and load estimations.
   
   Additionally I have a few questions
   
   - Should we make walSegsCreatedLastCheckpoint atomic ? In the future
   we can also add this to views maybe. It's an auxiliary suggestion.
   - ckpt_segs_added is defined as int but overflow threshold is 2^32 in
   comments. Shouldn't we use 2^31 for int ?
   - Maybe it's a bad idea but should we extend the tests with the
   wal_level set to minimal ?
   
   PS: I created a patch to expose wal_segments_created to
   pg_stat_checkpointer view. You can review it and enhance your patch if
   you need. I created it to explain my idea better so it can be
   destroyed after your review. But I couldn't create a patch for
   preceding questions.
   
   Regards,
   Demir.
   
   
   Xuneng Zhou <xunengzhou@gmail.com>, 25 Mar 2026 Çar, 03:10 tarihinde şunu yazdı:
   >
   > On Wed, Mar 25, 2026 at 9:11 AM Xuneng Zhou <xunengzhou@gmail.com> wrote:
   > >
   > > Hi Japin,
   > >
   > > Thanks for looking into this.
   > >
   > > On Tue, Mar 24, 2026 at 10:01 PM Japin Li <japinli@hotmail.com> wrote:
   > > >
   > > >
   > > > Hi, Xuneng
   > > >
   > > > On Tue, 24 Mar 2026 at 19:17, Xuneng Zhou <xunengzhou@gmail.com> wrote:
   > > > > Hi Zsolt,
   > > > >
   > > > > On Tue, Mar 24, 2026 at 1:55 PM Zsolt Parragi <zsolt.parragi@percona.com> wrote:
   > > > >
   > > > >  Hello!
   > > > >
   > > > >  This is a simple patch, but shouldn't it include at least some basic
   > > > >  tests verifying the new behavior?
   > > > >
   > > > > Thanks for looking into this. I've added a test for it. Please take a look.
   > > >
   > > > Thanks for updating the patch. A few comments on v2:
   > > >
   > > > 1.
   > > > +       (The probes listed next fire in sequence during checkpoint processing.)
   > > > +       arg0 is the number of buffers written. arg1 is the total number of
   > > >
   > > > These changes seem unnecessary. Additionally, there appears to be an
   > > > indentation issue.
   > >
   > > Yeah, I've removed these and fixed the indentation issue.
   > >
   > > > 2.
   > > > +    current = pg_atomic_read_u64(&XLogCtl->walSegmentsCreated);
   > > > +    CheckpointStats.ckpt_segs_added = (int)
   > > > +        (current - XLogCtl->walSegsCreatedLastCheckpoint);
   > > > +    XLogCtl->walSegsCreatedLastCheckpoint = current;
   > > >
   > > > Is integer overflow a concern here? It seems unlikely in practice.
   > >
   > > I don’t think overflow is a concern here, but it might still be
   > > helpful to add some comments to mention it.
   > >
   >
   > v4 fixed the inaccurate overflow numbers in comments.
   >
   > --
   > Best,
   > Xuneng
   

2. Re: log_checkpoints: count WAL segment creations from all processes

   Hüseyin Demir <huseyin.d3r@gmail.com> — 2026-05-17T09:10:36Z

   Hi,
   
   Thanks for the patch. The idea is good and can we introduce a new
   counter to pg_stat_checkpointer ? For example, we can add
   wal_segments_created to this view and it would be useful for capacity
   planning and load estimations.
   
   Additionally I have a few questions
   
   - Should we make walSegsCreatedLastCheckpoint atomic ? In the future
   we can also add this to views maybe. It's an auxiliary suggestion.
   - ckpt_segs_added is defined as int but overflow threshold is 2^32 in
   comments. Shouldn't we use 2^31 for int ?
   - Maybe it's a bad idea but should we extend the tests with the
   wal_level set to minimal ?
   
   PS: I created a patch to expose wal_segments_created to
   pg_stat_checkpointer view. You can review it and enhance your patch if
   you need. I created it to explain my idea better so it can be
   destroyed after your review. But I couldn't create a patch for
   preceding questions.
   
   Regards,
   Demir.