> > > Hi
> > >
> > > > > I may be wrong, and if I miss sth in previous mails, please give
> > > > > me some
> > > > hints.
> > > > > IMO, serial insertion with underlying parallel SELECT can be
> > > > > considered for foreign table or temporary table, as the
> > > > > insertions only
> > > > happened in the leader process.
> > > > >
> > > >
> > > > I don't think we support parallel scan for temporary tables. Can
> > > > you please try once both of these operations without Insert being
> > > > involved? If you are able to produce a parallel plan without
> > > > Insert then we can see why it is not supported with Insert.
> > >
> > > Sorry, may be I did not express it clearly, I actually means the case
> when insert's target(not in select part) table is temporary.
> > > And you are right that parallel select is not enabled when temporary
> table is in select part.
> > >
> >
> > I think Select can be parallel for this case and we should support this
> case.
> >
>
> So I think we're saying that if the target table is a foreign table or
> temporary table, it can be regarded as PARALLEL_RESTRICTED, right?
>
Yes
IMO, PARALLEL_RESTRICTED currently enable parallel select but disable parallel
insert.
So, the INSERT only happen in leader worker which seems safe to insert into
tempory/foreigh table.
In addition, there are some other restriction about parallel select which seems
can be removed:
1.- Target table has a parallel-unsafe trigger, index expression, column default
expression or check constraint
2.- Target table is a partitioned table with a parallel-unsafe partition key
expression or support function
If the Insert's target table is the type listed above, Is there some reasons
why we can not support parallel select ?
It seems only leader worker will execute the trigger and key-experssion which
seems safe.
(If I miss something about it, please let me know)
Best regards,
houzj
