Re: hyrax vs. RelationBuildPartitionDesc

Amit Langote <langote_amit_f8@lab.ntt.co.jp>

From: Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>
To: Tom Lane <tgl@sss.pgh.pa.us>, Robert Haas <robertmhaas@gmail.com>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2019-04-08T08:56:53Z
Lists: pgsql-hackers
On 2019/03/14 10:40, Amit Langote wrote:
> On 2019/03/14 5:18, Tom Lane wrote:
>> Robert Haas <robertmhaas@gmail.com> writes:
>>> On Wed, Mar 13, 2019 at 3:14 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>>>> Meanwhile, who's going to take point on cleaning up rd_partcheck?
>>>> I don't really understand this code well enough to know whether that
>>>> can share one of the existing partitioning-related sub-contexts.
>>
>>> To your question, I think it probably can't share a context.  Briefly,
>>> rd_partkey can't change ever, except that when a partitioned relation
>>> is in the process of being created it is briefly NULL; once it obtains
>>> a value, that value cannot be changed.  If you want to range-partition
>>> a list-partitioned table or something like that, you have to drop the
>>> table and create a new one.  I think that's a perfectly acceptable
>>> permanent limitation and I have no urge whatever to change it.
>>> rd_partdesc changes when you attach or detach a child partition.
>>> rd_partcheck is the reverse: it changes when you attach or detach this
>>> partition to or from a parent.
>>
>> Got it.  Yeah, it seems like the clearest and least bug-prone solution
>> is for those to be in three separate sub-contexts.  The only reason
>> I was trying to avoid that was the angle of how to back-patch into 11.
>> However, we can just add the additional context pointer field at the
>> end of the Relation struct in v11, and that should be good enough to
>> avoid ABI problems.
> 
> Agree that rd_partcheck needs its own context as you have complained in
> the past [1].
> 
> I think we'll need to back-patch this fix to PG 10 as well.  I've attached
> patches for all 3 branches.
> 
> Thanks,
> Amit
> 
> [1] https://www.postgresql.org/message-id/22236.1523374067%40sss.pgh.pa.us

Should I add this patch to Older Bugs [1]?

Thanks,
Amit

[1] https://wiki.postgresql.org/wiki/PostgreSQL_12_Open_Items




Commits

  1. Load relcache entries' partitioning data on-demand, not immediately.

  2. Prevent memory leaks associated with relcache rd_partcheck structures.

  3. Don't copy PartitionBoundInfo in set_relation_partition_info.

  4. Further reduce memory footprint of CLOBBER_CACHE_ALWAYS testing.

  5. Fix some oversights in commit 2455ab488.

  6. Defend against leaks into RelationBuildPartitionDesc.

  7. Allow ATTACH PARTITION with only ShareUpdateExclusiveLock.