Re: [HACKERS] Custom compression methods

From: Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
To: Ildus K <i(dot)kurbangaliev(at)postgrespro(dot)ru>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: [HACKERS] Custom compression methods
Date: 2017-11-21 20:42:37
Message-ID: 58c00f6a-8315-dc5d-1e2b-10861a86200f@2ndquadrant.com
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On 11/21/2017 09:28 PM, Ildus K wrote:
>> Hmmm, it still doesn't work for me. See this:
>>
>> test=# create extension pg_lz4 ;
>> CREATE EXTENSION
>> test=# create table t_lz4 (v text compressed lz4);
>> CREATE TABLE
>> test=# create table t_pglz (v text);
>> CREATE TABLE
>> test=# insert into t_lz4 select repeat(md5(1::text),300);
>> INSERT 0 1
>> test=# insert into t_pglz select * from t_lz4;
>> INSERT 0 1
>> test=# drop extension pg_lz4 cascade;
>> NOTICE: drop cascades to 2 other objects
>> DETAIL: drop cascades to compression options for lz4
>> drop cascades to table t_lz4 column v
>> DROP EXTENSION
>> test=# \c test
>> You are now connected to database "test" as user "user".
>> test=# insert into t_lz4 select repeat(md5(1::text),300);^C
>> test=# select * from t_pglz ;
>> ERROR: cache lookup failed for compression options 16419
>>
>> That suggests no recompression happened.
>
> I will check that. Is your extension published somewhere?
>

No, it was just an experiment, so I've only attached it to the initial
review. Attached is an updated version, with a fix or two.

regards

--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Attachment Content-Type Size
pg_lz4.tgz application/x-compressed-tar 1.5 KB

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