| From: | "Drouvot, Bertrand" <bdrouvot(at)amazon(dot)com> |
|---|---|
| To: | Andres Freund <andres(at)anarazel(dot)de> |
| Cc: | Ibrar Ahmed <ibrar(dot)ahmad(at)gmail(dot)com>, Amit Khandekar <amitdkhan(dot)pg(at)gmail(dot)com>, <fabriziomello(at)gmail(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, tushar <tushar(dot)ahuja(at)enterprisedb(dot)com>, "[pgdg] Robert Haas" <robertmhaas(at)gmail(dot)com>, Rahila Syed <rahila(dot)syed(at)2ndquadrant(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Minimal logical decoding on standbys |
| Date: | 2021-08-06 11:27:46 |
| Message-ID: | 7094ac62-340f-9b23-3af6-e24fe08c8697@amazon.com |
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| Lists: | pgsql-hackers |
Hi,
On 8/2/21 6:01 PM, Andres Freund wrote:
> While working on this I found a, somewhat substantial, issue:
>> If so, do you already have in mind a way to handle this? (I thought you
>> already had in mind a way to handle it so the question)
> Yes. I think we need to add a condition variable to be able to wait for
> WAL positions to change. Either multiple condition variables (one for
> the flush position, one for the replay position), or one that just
> changes more often. That way one can wait for apply without a race
> condition.
>
Thanks for the feedback.
Wouldn't a condition variable on the replay position be enough? I don't
get why the proposed one on the flush position is needed.
>> if not, what kind of additional
tests would you like to see?
> A few catalog rows being removed (e.g. due to DELETE and then VACUUM
> *without* full) and a standby without hot_standby_feedback catching
> that.
Test added in v23 attached.
Thanks
Bertrand
| Attachment | Content-Type | Size |
|---|---|---|
| v23-0005-Doc-changes-describing-details-about-logical-dec.patch | text/plain | 2.1 KB |
| v23-0004-New-TAP-test-for-logical-decoding-on-standby.patch | text/plain | 19.9 KB |
| v23-0003-Allow-logical-decoding-on-standby.patch | text/plain | 17.2 KB |
| v23-0002-Handle-logical-slot-conflicts-on-standby.patch | text/plain | 29.3 KB |
| v23-0001-Add-info-in-WAL-records-in-preparation-for-logic.patch | text/plain | 18.0 KB |
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