Horton

Re: unnesting multirange data types

Jonathan S. Katz <jkatz@postgresql.org>

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From: "Jonathan S. Katz" <jkatz@postgresql.org>
To: Alexander Korotkov <aekorotkov@gmail.com>, Justin Pryzby <pryzby@telsasoft.com>
Cc: Alvaro Herrera <alvherre@alvh.no-ip.org>, Tom Lane <tgl@sss.pgh.pa.us>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2021-06-12T22:16:24Z
Lists: pgsql-hackers 
On 6/12/21 5:57 PM, Alexander Korotkov wrote:
> On Sat, Jun 12, 2021 at 2:44 AM Alexander Korotkov <aekorotkov@gmail.com> wrote:
>> ()On Sat, Jun 12, 2021 at 2:30 AM Justin Pryzby <pryzby@telsasoft.com> wrote:
>>> On Fri, Jun 11, 2021 at 11:37:58PM +0300, Alexander Korotkov wrote:
>>>> On Fri, Jun 11, 2021 at 1:04 AM Justin Pryzby <pryzby@telsasoft.com> wrote:
>>>>>
>>>>> +{ oid => '1293', descr => 'expand mutlirange to set of ranges',
>>>>>
>>>>> typo: mutlirange
>>>>
>>>> Fixed, thanks.
>>>>
>>>> The patch with the implementation of both unnest() and cast to array
>>>> is attached.  It contains both tests and docs.
>>>
>>> |+   The multirange could be explicitly cast to the array of corresponding
>>> should say: "can be cast to an array of corresponding.."
>>>
>>> |+ * Cast multirange to the array of ranges.
>>> I think should be: *an array of ranges
>>
>> Thank you for catching this.
>>
>>> Per sqlsmith, this is causing consistent crashes.
>>> I took one of its less appalling queries and simplified it to this:
>>>
>>> select
>>> pg_catalog.multirange_to_array(
>>>     cast(pg_catalog.int8multirange() as int8multirange)) as c2
>>> from (select 1)x;
>>
>> It seems that multirange_to_array() doesn't handle empty multiranges.
>> I'll post an updated version of the patch tomorrow.
> 
> A revised patch is attached.  Now empty multiranges are handled
> properly (and it's covered by tests).  Typos are fixed as well.

Tested both against my original cases using both SQL + PL/pgSQL. All
worked well. I also tested the empty multirange case as well.

Overall the documentation seems to make sense, I'd suggest:

+  <para>
+   The multirange can be cast to an array of corresponding ranges.
+  </para>

becomes:

+  <para>
+   A multirange can be cast to an array of ranges of the same type.
+  </para>

Again, I'll defer to others on the code, but this seems to solve the use
case I presented. Thanks for the quick turnaround!

Jonathan

Commits

  1. Fix small inconsistencies in catalog definition of multirange operators

  2. Revert 29854ee8d1 due to buildfarm failures

  3. Copy-edit text for the pg_terminate_backend() "timeout" parameter.

  4. Add missing pg_description strings for pg_type entries.

  5. Fix pg_description entries for jsonb_to_record() and jsonb_to_recordset().

  6. docs: clarify JSONB operator descriptions

  7. Set procost to 10 for each of the pg_foo_is_visible() functions.

  8. Make use of LATERAL in information_schema.sequences view.

  9. Add pg_trigger_depth() function

  10. Add database comments to template0 and postgres databases, and improve