From: | Alexey Kondratov <a(dot)kondratov(at)postgrespro(dot)ru> |
---|---|
To: | Robert Haas <robertmhaas(at)gmail(dot)com>, Michael Paquier <michael(at)paquier(dot)xyz> |
Cc: | Surafel Temesgen <surafel3000(at)gmail(dot)com>, Alexander Korotkov <a(dot)korotkov(at)postgrespro(dot)ru>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Allow CLUSTER, VACUUM FULL and REINDEX to change tablespace on the fly |
Date: | 2019-09-19 14:40:41 |
Message-ID: | f4881081-14cd-46d2-8e81-75003a7a7c83@postgrespro.ru |
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Lists: | pgsql-hackers |
On 19.09.2019 16:21, Robert Haas wrote:
> On Thu, Sep 19, 2019 at 12:43 AM Michael Paquier <michael(at)paquier(dot)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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