| From: | shihao zhong <zhong950419(at)gmail(dot)com> |
|---|---|
| To: | Shlok Kyal <shlok(dot)kyal(dot)oss(at)gmail(dot)com> |
| Cc: | yangboyu <yangboyu(dot)yby(at)alibaba-inc(dot)com>, pgsql-hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>, rhaas <rhaas(at)postgresql(dot)org> |
| Subject: | Re: logical decoding: skip unnecessary snapshot distribution. |
| Date: | 2026-09-05 03:36:43 |
| Message-ID: | CAGRkXqT-FY_Y8Bp_ueN7jbxSE2DgNFpZhMkxPvC=7uTaWLf5WA@mail.gmail.com |
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| Lists: | pgsql-hackers |
Hi Boyu,
I ran your patch with your reproducer on current master and got
the same result you reported. I have about 19 MB of spill without the
patch, and 0 with it.
Also, FYI: there is another thread working on the same problem
from a different direction:
"Lazy snapshot distribution in logical decoding"
https://www.postgresql.org/message-id/flat/578D6ABA-FC6B-4E08-955F-3493BA6FACA1%40gmail.com
That patch does not skip any snapshots; it waits to hand one out
until a transaction actually needs it. Your patch skips the work
completely when the commit came from another database. Both change
the same code, so the two threads should know about each other.
I plan to take a closer look at your patch for Sholok's case this weekend.
Thanks,
Shihao
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