Re: Allow CLUSTER, VACUUM FULL and REINDEX to change tablespace onthe fly

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От Alexey Kondratov
Тема Re: Allow CLUSTER, VACUUM FULL and REINDEX to change tablespace onthe fly
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Msg-id f4881081-14cd-46d2-8e81-75003a7a7c83@postgrespro.ru
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Ответ на Re: Allow CLUSTER, VACUUM FULL and REINDEX to change tablespace onthe fly  (Robert Haas <robertmhaas@gmail.com>)
Ответы Re: Allow CLUSTER, VACUUM FULL and REINDEX to change tablespace onthe fly  (Michael Paquier <michael@paquier.xyz>)
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On 19.09.2019 16:21, Robert Haas wrote:
> On Thu, Sep 19, 2019 at 12:43 AM Michael Paquier <michael@paquier.xyz> wrote:
>> It seems to me that it would be good to keep the patch as simple as
>> possible for its first version, and split it into two if you would
>> like to add this new option instead of bundling both together.  This
>> makes the review of one and the other more simple.  Anyway, regarding
>> the grammar, is SET TABLESPACE really our best choice here?  What
>> about:
>> - TABLESPACE = foo, in parenthesis only?
>> - Only using TABLESPACE, without SET at the end of the query?
>>
>> SET is used in ALTER TABLE per the set of subqueries available there,
>> but that's not the case of REINDEX.
> So, earlier in this thread, I suggested making this part of ALTER
> TABLE, and several people seemed to like that idea. Did we have a
> reason for dropping that approach?

If we add this option to REINDEX, then for 'ALTER TABLE tb_name action1, 
REINDEX SET TABLESPACE tbsp_name, action3' action2 will be just a direct 
alias to 'REINDEX TABLE tb_name SET TABLESPACE tbsp_name'. So it seems 
practical to do this for REINDEX first.

The only one concern I have against adding REINDEX to ALTER TABLE in 
this context is that it will allow user to write such a chimera:

ALTER TABLE tb_name REINDEX SET TABLESPACE tbsp_name, SET TABLESPACE 
tbsp_name;

when they want to move both table and all the indexes. Because simple

ALTER TABLE tb_name REINDEX, SET TABLESPACE tbsp_name;

looks ambiguous. Should it change tablespace of table, indexes or both?


-- 
Alexey Kondratov

Postgres Professional https://www.postgrespro.com
Russian Postgres Company




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