| From: | Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)lists(dot)postgresql(dot)org |
| Subject: | Re: Isn't partition drop code seriously at risk of deadlock? |
| Date: | 2017-11-28 00:43:25 |
| Message-ID: | d52e8cc7-b3e3-8d57-1ca6-e90a18003df2@lab.ntt.co.jp |
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| Lists: | pgsql-hackers |
On 2017/11/28 9:04, Tom Lane wrote:
> The complaint in bug #14927 that heap_drop_with_catalog is not bothering
> to check for SearchSysCache lookup failure (in code evidently newly added
> for the partition feature) seems to me to be only scratching the surface
> of what's wrong with that code. In particular, I do not understand how
> it can possibly be deadlock-free to be trying to grab AccessExclusiveLock
> on a partition's parent table when we already have such a lock on the
> partition. Which we do, or at least had better, long before we get to
> heap_drop_with_catalog.
We do that as of 258cef12540fa1 [1]. The lock on the parent is taken in
RangeVarCallbackForDropRelation() before the partition itself is locked.
Thanks,
Amit
[1]
https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=258cef12540fa1
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