| From: | Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com> |
|---|---|
| To: | Евгений Шишкин <itparanoia(at)gmail(dot)com> |
| Cc: | Ildus Kurbangaliev <i(dot)kurbangaliev(at)postgrespro(dot)ru>, Andres Freund <andres(at)anarazel(dot)de>, Robert Haas <robertmhaas(at)gmail(dot)com>, Oleg Bartunov <obartunov(at)gmail(dot)com>, Craig Ringer <craig(at)2ndquadrant(dot)com>, Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: [HACKERS] Custom compression methods |
| Date: | 2017-11-20 16:31:45 |
| Message-ID: | 641e18b7-1bb6-ba8d-fddb-d0259f970897@2ndquadrant.com |
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| Lists: | pgsql-hackers |
On 11/20/2017 04:43 PM, Евгений Шишкин wrote:
>
>
>> On Nov 20, 2017, at 18:29, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com> wrote:
>>
>>>
>>> What about instead of dropping column we leave data uncompressed?
>>>
>>
>> That requires you to go through the data and rewrite the whole table.
>> And I'm not aware of a DROP command doing that, instead they just drop
>> the dependent objects (e.g. DROP TYPE, ...). So per PLOS the DROP
>> COMPRESSION METHOD command should do that too.
>
> Well, there is no much you can do with DROP TYPE. But i'd argue that compression
> is different. We do not drop data in case of DROP STATISTICS or DROP INDEX.
>
But those DROP commands do not 'invalidate' data in the heap, so there's
no reason to drop the columns.
> At least there should be a way to easily alter compression method then.
>
+1
regards
--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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