On Wed, Oct 7, 2020 at 12:40 AM Bharath Rupireddy
<bharath.rupireddyforpostgres@gmail.com> wrote:
>
> In parallel, we are not doing anything(due to the same reason
> explained in above comment) to find whether there is a foreign
> partition or not while deciding to go with parallel/non-parallel copy,
> we are just throwing an error during the first tuple insertion into
> the partition.
>
> errmsg("cannot perform PARALLEL COPY if partition has BEFORE/INSTEAD
> OF triggers, or if the partition is foreign partition"),
> errhint("Try COPY without PARALLEL option")));
>
I may well need to do something similar for parallel INSERT, but I'm
kind of surprised it can't be detected earlier (?).
Will need to further test this.
>
> Allowing the leader to execute before statement triggers at Gather
> node level before invoking the parallel plan and then parallel inserts
> makes sense. But if there are any after statement triggers, there may
> come transition tables, see Amit's findings under Case-1 in [1] and we
> must disable parallelism in that case.
>
> [1] -
https://www.postgresql.org/message-id/flat/CAA4eK1%2BANNEaMJCCXm4naweP5PLY6LhJMvGo_V7-Pnfbh6GsOA%40mail.gmail.com
>
The patch I last posted for parallel INSERT does detect use of
transition tables in this case (trigdesc->trig_insert_new_table) and
disables INSERT parallelism (I tested it against Amit's example), yet
still otherwise allows AFTER STATEMENT triggers for parallel INSERT.
Regards,
Greg Nancarrow
Fujitsu Australia