On 1/19/21 7:23 AM, Amit Langote wrote:
> On Tue, Jan 19, 2021 at 2:06 PM tsunakawa.takay@fujitsu.com
> <tsunakawa.takay@fujitsu.com> wrote:
>> From: Amit Langote <amitlangote09@gmail.com>
>>> I apologize in advance for being maybe overly pedantic, but I noticed
>>> that, in ExecInitModifyTable(), you decided to place the call outside
>>> the loop that goes over resultRelations (shown below), although my
>>> intent was to ask to place it next to the BeginForeignModify() in that
>>> loop.
>>
>> Actually, I tried to do it (adding the GetModifyBatchSize() call after BeginForeignModify()), but it failed.
BecausepostgresfdwGetModifyBatchSize() wants to know if RETURNING is specified, and ResultRelInfo->projectReturning is
createdafter the above part. Considering the context where GetModifyBatchSize() implementations may want to know the
environment,I placed the call as late as possible in the initialization phase. As for the future(?) multi-target DML
statements,I think we can change this together with other many(?) parts that assume a single target table.
>
> Okay, sometime later then.
>
> I wasn't sure if bringing it up here would be appropriate, but there's
> a patch by me to refactor ModfiyTable result relation allocation that
> will have to remember to move this code along to an appropriate place
> [1]. Thanks for the tip about the dependency on how RETURNING is
> handled. I will remember it when rebasing my patch over this.
>
Thanks. The last version (v12) should be addressing all the comments and
seems fine to me, so barring objections I'll get that pushed shortly.
One thing that seems a bit annoying is that with the partitioned table
the explain (verbose) looks like this:
QUERY PLAN
-----------------------------------------------------
Insert on public.batch_table
-> Function Scan on pg_catalog.generate_series i
Output: i.i
Function Call: generate_series(1, 66)
(4 rows)
That is, there's no information about the batch size :-( But AFAICS
that's due to how explain shows (or rather does not) partitions in this
type of plan.
regards
--
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
