Re: Parallel Inserts in CREATE TABLE AS

For set_append_rel_size(), it seems this is the difference
between query_level != 1 and query_level == 1:

+ (root->parent_root->parse->CTASParallelInsInfo &
CTAS_PARALLEL_INS_IGN_TUP_COST_APPEND) &&

Maybe extract the common conditions into its own expression / variable so
that the code is easier to read.

Cheers

On Mon, Dec 14, 2020 at 4:50 AM Hou, Zhijie <houzj(dot)fnst(at)cn(dot)fujitsu(dot)com>
wrote:

> Hi
>
> > Attaching v11 patch set. Please review it further.
>
> Currently with the patch, we can allow parallel CTAS when topnode is
> Gather.
> When top-node is Append and Gather is the sub-node of Append, I think we
> can still enable
> Parallel CTAS by pushing Parallel CTAS down to the sub-node Gather, such
> as:
>
> Append
> ------>Gather
> --------->Create table
> ------------->Seqscan
> ------>Gather
> --------->create table
> ------------->Seqscan
>
> And the use case seems common to me, such as:
> select * from A where xxx union all select * from B where xxx;
>
> I attatch a WIP patch which just show the possibility of this feature.
> The patch is based on the latest v11-patch.
>
> What do you think?
>
> Best regards,
> houzj
>
>
>
>
>
>