Horton

RE: How can end users know the cause of LR slot sync delays?

Hayato Kuroda (Fujitsu) <kuroda.hayato@fujitsu.com>

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From: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>
To: 'Shlok Kyal' <shlok.kyal.oss@gmail.com>
Cc: Amit Kapila <amit.kapila16@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Ashutosh Sharma <ashu.coek88@gmail.com>
Date: 2025-10-01T02:56:30Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Rename column slotsync_skip_at to slotsync_last_skip.

  2. Add slotsync_skip_reason column to pg_replication_slots view.

  3. Fix test failure caused by commit 76b78721ca.

  4. Fix a BF failure caused by commit 76b78721ca.

  5. Add slotsync skip statistics.

Attachments

Dear Shlok,

> Thanks for updating the patch. Here are my comments.

I found one more comment.

```
+       /*
+        * If found_consistent_snapshot is not NULL and a consistent snapshot is
+        * found set the slot sync skip reason to none. Else, if consistent
+        * snapshot is not found the stats will be updated in the function
+        * update_and_persist_local_synced_slot
+        */
+       if (!found_consistent_snapshot || *found_consistent_snapshot)
+               update_slot_sync_skip_stats(slot, SS_SKIP_NONE);
```

I think the condition is confusing; in code level there is a path that
found_consistent_snapshot is NULL but synchronization happened. (Not sure it is
possible though).

I think it is better to put update_slot_sync_skip_stats() near the sync part.
If the snapshot exists from the beginning, it can be done unconditionally,
otherwise we can check again. Attached .diffs file implements it.

Best regards,
Hayato Kuroda
FUJITSU LIMITED