The attached patch try to replace 'heap_open' with 'LockRelationOid' when
locking parent table.
It improved dropping a table with 7000 partitions.

2017-04-25 15:07 GMT+08:00 Amit Langote <langote_amit...@lab.ntt.co.jp>:

> $SUBJECT, if the table has, say, 2000 partitions.
>
> The main reason seems to be that RelationBuildPartitionDesc() will be
> called that many times within the same transaction, which perhaps we
> cannot do much about right away.  But one thing we could do is to reduce
> the impact of memory allocations it does.  They are currently leaked into
> the caller's context, which may not be reset immediately (such as
> PortalHeapMemory).  Instead of doing it in the caller's context, use a
> temporary context that is deleted before returning.  Attached is a patch
> for that.  On my local development VM, `drop table
> table_with_2000_partitions` finished in 27 seconds with the patch instead
> of more than 20 minutes that it currently takes.
>
> Thoughts?
>
> Adding this to the open items list.
>
> Thanks,
> Amit
>
> PS: this was actually mentioned by Ragnar Ouchterlony who reported some
> bugs back in declarative partitioning in January [1]
>
> [1]
> https://www.postgresql.org/message-id/17d89e08-874b-c1b1-
> aa46-12d5afb26235%40agama.tv
>
>
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Attachment: 0001-Don-t-building-a-relcache-entry-since-we-don-t-need-.patch
Description: Binary data

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