| From: | Aleksander Alekseev <aleksander(at)tigerdata(dot)com> |
|---|---|
| To: | pgsql-hackers(at)lists(dot)postgresql(dot)org |
| Cc: | Zsolt Parragi <zsolt(dot)parragi(at)percona(dot)com> |
| Subject: | Re: Write skew observed under serializable isolation |
| Date: | 2026-09-23 22:39:53 |
| Message-ID: | CAJ7c6TMCQmm-7akUPPE0GoAwYdeN5E==KU87=E8g9yjArVHXMQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
Hi Zsolt,
> That's a way to fix it, but I am not sure that it is the proper way to
> do it because it locks way more than needed.
>
> [...]
This looks like the same concern Matthias expressed above.
Let's be mindful of the fact that SIREAD locks despite the name are
not actually locks. Also our SERIALIZABLE implementation allows
false-positives by design [1].
Perhaps there is a smart way of minimizing false positives but
personally I don't instantly see them. Firstly we should fix the
broken feature and optimizations can be discussed as a separate patch.
Users concerned with rollbacks can always choose other isolation
levels.
[1]: https://arxiv.org/abs/1208.4179
--
Best regards,
Aleksander Alekseev
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