| From: | Heikki Linnakangas <hlinnaka(at)iki(dot)fi> |
|---|---|
| To: | Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru>, Andrey Borodin <x4mmm(at)yandex-team(dot)ru> |
| Cc: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Shubham Barai <shubhambaraiss(at)gmail(dot)com>, Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Andrew Borodin <amborodin86(at)gmail(dot)com>, Kevin Grittner <kgrittn(at)gmail(dot)com> |
| Subject: | Re: [HACKERS] GSoC 2017: weekly progress reports (week 6) |
| Date: | 2018-04-09 06:23:21 |
| Message-ID: | fe55ac37-576d-d806-d1b7-c745b0a4892a@iki.fi |
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| Thread: | |
| Lists: | pgsql-hackers pgsql-www |
On 16/03/18 00:26, Alexander Korotkov wrote:
> On Tue, Mar 13, 2018 at 3:26 PM, Andrey Borodin <x4mmm(at)yandex-team(dot)ru> wrote:
>> On 13/03/18 14:02, Alexander Korotkov wrote:
>>> And what happen if somebody concurrently set (fastupdate = on)?
>>> Can we miss conflicts because of that?
>>
>> No, AccessExclusiveLock will prevent this kind of problems with enabling
>> fastupdate.
>
> True. I didn't notice that ALTER INDEX SET locks index in so high mode.
> Thus, everything is fine from this perspective.
Nope, an AccessExclusiveLock is not good enough. Predicate locks stay
around after the transaction has committed and regular locks have been
released.
Attached is a test case that demonstrates a case where we miss a
serialization failure, when fastupdate is turned on concurrently. It
works on v10, but fails to throw a serialization error on v11.
- Heikki
| Attachment | Content-Type | Size |
|---|---|---|
| predicate-gin-fastupdate-fail-demo.patch | text/x-patch | 2.7 KB |
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