Re: Adding support for Default partition in partitioning

Hi Robert,

>> > 0007:
> >> > This patch introduces code to check if the scanning of default
> partition
> >> > child
> >> > can be skipped if it's constraints are proven.
> >>
> >> If I understand correctly, this is actually a completely separate
> >> feature not intrinsically related to default partitioning.
> >
> > I don't see this as a new feature, since scanning the default partition
> > will be introduced by this series of patches only, and rather than a
> > feature this can be classified as a completeness of default skip
> > validation logic. Your thoughts?
>
> Currently, when a partitioned table is attached, we check whether all
> the scans can be checked but not whether scans on some partitions can
> be attached. So there are two separate things:
>
> 1. When we introduce default partitioning, we need scan the default
> partition either when (a) any partition is attached or (b) any
> partition is created.
>
> 2. In any situation where scans are needed (scanning the partition
> when it's attached, scanning the default partition when some other
> partition is attached, scanning the default when a new partition is
> created), we can run predicate_implied_by for each partition to see
> whether the scan of that partition can be skipped.
>
> Those two changes are independent. We could do (1) without doing (2)
> or (2) without doing (1) or we could do both. So they are separate
> features.
>
>
In my V25 series(patch 0005) I have only addressed half of (2) above
i.e. code to check whether the scan of a partition of default partition
can be skipped when other partition is being added. Amit Langote
has submitted[1] a separate patch(0003) to address skipping the scan
of the children of relation when it's being attached as a partition.

[1]
https://www.postgresql.org/message-id/4cd13b03-846d-dc65-89de-1fd9743a3869%40lab.ntt.co.jp

Regards,
Jeevan Ladhe