Re: pg_dump -Fd and compression level

From: Marc Mamin <M(dot)Mamin(at)intershop(dot)de>
To: Andrew Dunstan <andrew(at)dunslane(dot)net>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>
Cc: "'michael(dot)paquier(at)gmail(dot)com'" <michael(dot)paquier(at)gmail(dot)com>
Subject: Re: pg_dump -Fd and compression level
Date: 2015-07-24 21:22:39
Message-ID: B6F6FD62F2624C4C9916AC0175D56D8828C1800E@jenmbs01.ad.intershop.net
Views: Raw Message | Whole Thread | Download mbox | Resend email
Thread:
Lists: pgsql-hackers


>> After our last upgrade, we've noticed a 10-20% size increase of our dump size.
>> This comes from our backup scripts were pg_dump was called without setting -Z
>>
>> So it seems, that this fix did modify the default compression to use:
>> http://michael.otacoo.com/postgresql-2/pg_dump-directory-format-compression/
>>
>> not sure if this is expected or if this commit accidently changed the default compression, setting it too low.
>>
>> moreover, the doc is somewhat unclear here as it mentions all formats but the directory one:
>>
>> -Z 0..9
>> --compress=0..9
>>
>> Specify the compression level to use. Zero means no compression.
>> For the custom archive format, this specifies compression of individual
>> table-data segments, and the default is to compress at a moderate level.
>> For plain text output, setting a nonzero compression level causes the entire
>> output file to be compressed, as though it had been fed through gzip;
>> but the default is not to compress.
>> The tar archive format currently does not support compression at all.
>>
>> shouldn't that be changed to
>>
>> - For the custom archive format
>> + For the directory and custom archive formats
>>
>>
>
>What did you upgrade from/to?

9.3.6 to 9.3.9

this is bound to this 9.3.7 fix:
"In pg_dump, fix failure to honor -Z compression level option together with -Fd (Michael Paquier)"

I understand that the modification is wishfull, but the change has nevertheless a non negligable impact.
This had increased our backup repository of about 1TB within a few weeks if we hadn't noticed it.

regards,

Marc mamin

In response to

Responses

Browse pgsql-hackers by date

  From Date Subject
Next Message Tom Lane 2015-07-24 22:36:21 Re: TABLESAMPLE patch is really in pretty sad shape
Previous Message Joe Conway 2015-07-24 19:58:12 Re: RLS fails to work with UPDATE ... WHERE CURRENT OF