Re: Update does not move row across foreign partitions in v11

(2019/03/06 15:34), Amit Langote wrote:
> On 2019/03/06 15:10, Etsuro Fujita wrote:
>> --- a/doc/src/sgml/ddl.sgml
>> +++ b/doc/src/sgml/ddl.sgml
>> @@ -3376,6 +3376,13 @@ ALTER TABLE measurement ATTACH PARTITION
>> measurement_y2008m02
>> </para>
>> </listitem>
>>
>> +<listitem>
>> +<para>
>> +<command>UPDATE</command> row movement is not supported in the cases
>> + where the old row is contained in a foreign table partition.
>> +</para>
>> +</listitem>
>>
>> ISTM that it's also a limitation that rows can be moved from a local
>> partition to a foreign partition *if the FDW support tuple routing*, so I
>> would vote for mentioning that as well here.
>
> Thanks for checking.
>
> I have updated the patch to include a line about this in the same
> paragraph, because maybe we don't need to make a new<listitem> for it.

Thanks for the patch!

The patch looks good to me, but one thing I'm wondering is: as suggested
by David, it would be better to rephrase this mention in the UPDATE
reference page, in a single commit:

"Currently, rows cannot be moved from a partition that is a foreign
table to some other partition, but they can be moved into a foreign
table if the foreign data wrapper supports it."

I don't think it needs to be completely rephrased; it's enough for me to
rewrite it to something like this:

"Currently, rows cannot be moved from a foreign-table partition to some
other partition, but they can be moved into a foreign-table partition if
the foreign data wrapper supports tuple routing."

And to make maintenance work easy, I think it might be better to just
put this on the limitations section of 5.10. Table Partitioning. What
do you think about that?

Best regards,
Etsuro Fujita