main log encoding problem

[yi huang <yi.codeplayer@xxxxxxxxx>]

I'm using postgresql 9.1.3 from debian squeeze-backports with zh_CN.UTF-8 locale, i find my main log (which is "/var/log/postgresql/postgresql-9.1-main.log") contains "???" which indicate some sort of charset encoding problem.

But error messages related to pgsql is fine, only other system messages have this problem, for example:

2012-05-19 16:06:12 CST ??:  ?????????? 2012-05-19 16:06:10 CST
2012-05-19 16:06:12 CST ??:  ???????????
2012-05-19 16:06:12 CST ??:  ???autovacuum
2012-05-19 16:06:12 CST ??:  ???????
2012-05-19 16:07:16 CST 错误:  角色"postgres" 已经存在    (in english: Error: role "postgres" already exists)
2012-05-19 16:07:16 CST 语句:  CREATE ROLE postgres;
2012-05-19 16:07:16 CST 错误:  语言 "plpgsql" 已经存在     (in english: Error: language "plpgsql" already exists)
2012-05-19 16:07:16 CST 语句:  CREATE PROCEDURAL LANGUAGE plpgsql;
2012-05-19 16:08:23 CST ????:  ?? "huangyi" ???
2012-05-19 16:08:52 CST ????:  ?? "huangyi" ???
2012-05-19 16:09:01 CST ??:  ???????(zlfund)????????(huangyi) ???
2012-05-19 16:09:01 CST ????:  Peer authentication failed for user "zlfund"
2012-05-19 16:09:34 CST ??:  ???????(zlfund)????????(huangyi) ???
2012-05-19 16:09:34 CST ????:  Peer authentication failed for user "zlfund"

I guess it has something to do with packaging problem rather than postgresql itself, but it would be great if you can give me some clue where the problem might be.

My best regards.

Yi Huang.