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  1. Fix yet another issue with step generation in partition pruning.

  2. Fix some issues with step generation in partition pruning.

  1. Yet another issue with step generation in partition pruning

    Etsuro Fujita <etsuro.fujita@gmail.com> — 2020-08-04T12:45:31Z

    Commit 13838740f fixed some issues with step generation in partition
pruning, but as I mentioned in [1], I noticed that there is yet
another issue: get_steps_using_prefix() assumes that clauses in the
passed-in prefix list are sorted in ascending order of their partition
key numbers, but the caller (i.e., gen_prune_steps_from_opexps())
doesn’t ensure that in the case of range partitioning, leading to an
assertion failure.  Here is an example causing such a failure, which
would happen with/without that commit:

create table rp_prefix_test2 (a int, b int, c int) partition by range (a, b, c);
create table rp_prefix_test2_p1 partition of rp_prefix_test2 for
values from (1, 1, 0) to (1, 1, 10);
create table rp_prefix_test2_p2 partition of rp_prefix_test2 for
values from (2, 2, 0) to (2, 2, 10);
select * from rp_prefix_test2 where a <= 1 and b <= 1 and b = 1 and c <= 0;

I don't think we write queries like this, but for this query, the
caller would create the prefix list for the last partition key “c”
{b=1, a<=1, b<=1} (the clauses are not sorted properly!), then calling
get_steps_using_prefix(), which leads to an assertion failure.
Attached is a patch for fixing this issue.

Best regards,
Etsuro Fujita

[1] https://www.postgresql.org/message-id/CAPmGK15%3Dc8Q-Ac3ogzZp_d6VsfRYSL2tD8zLwy_WYdrMXQhiCQ%40mail.gmail.com

  2. Re: Yet another issue with step generation in partition pruning

    Amit Langote <amitlangote09@gmail.com> — 2020-08-05T08:12:54Z

    Fujita-san,

Thanks a lot for your time on fixing these multi-column range
partition pruning issues.  I'm sorry that I failed to notice the
previous two reports on -bugs for which you committed a fix last week.

On Tue, Aug 4, 2020 at 9:46 PM Etsuro Fujita <etsuro.fujita@gmail.com> wrote:
> Commit 13838740f fixed some issues with step generation in partition
> pruning, but as I mentioned in [1], I noticed that there is yet
> another issue: get_steps_using_prefix() assumes that clauses in the
> passed-in prefix list are sorted in ascending order of their partition
> key numbers, but the caller (i.e., gen_prune_steps_from_opexps())
> doesn’t ensure that in the case of range partitioning, leading to an
> assertion failure.  Here is an example causing such a failure, which
> would happen with/without that commit:
>
> create table rp_prefix_test2 (a int, b int, c int) partition by range (a, b, c);
> create table rp_prefix_test2_p1 partition of rp_prefix_test2 for
> values from (1, 1, 0) to (1, 1, 10);
> create table rp_prefix_test2_p2 partition of rp_prefix_test2 for
> values from (2, 2, 0) to (2, 2, 10);
> select * from rp_prefix_test2 where a <= 1 and b <= 1 and b = 1 and c <= 0;
>
> I don't think we write queries like this, but for this query, the
> caller would create the prefix list for the last partition key “c”
> {b=1, a<=1, b<=1} (the clauses are not sorted properly!), then calling
> get_steps_using_prefix(), which leads to an assertion failure.

That analysis is spot on.

> Attached is a patch for fixing this issue.

I have looked at the patch and played around with it using the
regression tests you've added recently. I was not able to find any
results that looked surprising.

Thanks again.

--
Amit Langote
EnterpriseDB: http://www.enterprisedb.com

  3. Re: Yet another issue with step generation in partition pruning

    Etsuro Fujita <etsuro.fujita@gmail.com> — 2020-08-05T15:20:50Z

    Amit-san,

On Wed, Aug 5, 2020 at 5:13 PM Amit Langote <amitlangote09@gmail.com> wrote:
> Thanks a lot for your time on fixing these multi-column range
> partition pruning issues.  I'm sorry that I failed to notice the
> previous two reports on -bugs for which you committed a fix last week.

No problem.

> On Tue, Aug 4, 2020 at 9:46 PM Etsuro Fujita <etsuro.fujita@gmail.com> wrote:
> > Attached is a patch for fixing this issue.
>
> I have looked at the patch and played around with it using the
> regression tests you've added recently. I was not able to find any
> results that looked surprising.

That's good to hear!  Thanks for reviewing!  Will push the patch tomorrow.

Best regards,
Etsuro Fujita

  4. Re: Yet another issue with step generation in partition pruning

    Etsuro Fujita <etsuro.fujita@gmail.com> — 2020-08-07T05:55:40Z

    On Thu, Aug 6, 2020 at 12:20 AM Etsuro Fujita <etsuro.fujita@gmail.com> wrote:
> Will push the patch tomorrow.

Done.  (I didn't have time for this, because I was terribly busy with
other stuff.)

Best regards,
Etsuro Fujita

  5. Re: Yet another issue with step generation in partition pruning

    Etsuro Fujita <etsuro.fujita@gmail.com> — 2020-08-07T13:46:39Z

    On Fri, Aug 7, 2020 at 2:55 PM Etsuro Fujita <etsuro.fujita@gmail.com> wrote:
> On Thu, Aug 6, 2020 at 12:20 AM Etsuro Fujita <etsuro.fujita@gmail.com> wrote:
> > Will push the patch tomorrow.
>
> Done.  (I didn't have time for this, because I was terribly busy with
> other stuff.)

I mean I didn't have time for this *yesterday*.

Best regards,
Etsuro Fujita