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Re^2: DBD::Pg encodes Perlstring to UTF-8 bytes instead of WIN1252 regardless client encoding

by Pickwick (Beadle)
on Jan 30, 2014 at 18:57 UTC ( #1072712=note: print w/ replies, xml ) Need Help??


in reply to Re: DBD::Pg encodes Perlstring to UTF-8 bytes instead of WIN1252 regardless client encoding
in thread DBD::Pg encodes Perlstring to UTF-8 bytes instead of WIN1252 regardless client encoding

According to the docs, Postgres automatically recodes from table to client encoding and vice versa if you tell it to use a specific client encoding. So it should be pretty transparent.

That's what I thought as well, but it simply doesn't behave that way on my systems. Client encoding tells WIN1252, but UTF-8 encoded bytes are send. The only thing I have in between is DBIx::Log4perl which logs the statements send to the server and shows that UTF-8 bytes are send.


Comment on Re^2: DBD::Pg encodes Perlstring to UTF-8 bytes instead of WIN1252 regardless client encoding
Re^3: DBD::Pg encodes Perlstring to UTF-8 bytes instead of WIN1252 regardless client encoding
by moritz (Cardinal) on Jan 30, 2014 at 19:00 UTC
      I did, but that's not the point of my question why I need to at all to get it working, because depending on the client encoding DBD::Pg should properly encode the data itself.
Re^3: DBD::Pg encodes Perlstring to UTF-8 bytes instead of WIN1252 regardless client encoding
by mje (Deacon) on Jan 31, 2014 at 08:50 UTC

    DBIx::Log4perl sees the data before it is sent to the database by DBD::Pg so you cannot rely on what you see in its output as DBD::Pg can change the data.

    I took a casual glance at DBD::Pg code and all the UTF8 stuff seemed to be wrapped in pg_enable_utf8. Are you binding the data as parameters when it is inserted?

    The trouble here is there are a number of variables. You database uses 1252 encoding. What is your postgres client charset set to and what is the encoding of the data you pass to DBD::Pg when it fails and do you have pg_enable_utf8 on?

      DBIx::Log4perl sees the data before it is sent to the database by DBD::Pg so you cannot rely on what you see in its output as DBD::Pg can change the data.

      In theory, yes, but practically Log4perl was logging as expected a line before the SQL statement and the output of DBIx makes sense for the problem I described. If I encode the data to WIN1252 before passing it to DBI the logged output of DBIx change as well, therefore my strong guess that DBIx is logging what gets send to the database.

      Are you binding the data as parameters when it is inserted?

      No, the application simply creates a SQL string by concatenating different UTF-8 Perlstrings together, pushes that with a "do" and the whole string formed by SQL command and values gets encoded to UTF-8.

      What is your postgres client charset set to

      It's automatically detected as WIN1252 when the problem occurs, which makes perfectly sense on Windows and the Linux I tested. Another Ubuntu server automatically detects it as UTF-8 instead, because it has an UTF-8 locale. If I manually change it to UTF-8 everything works as expected, the database server properly encodes UTF-8 bytes to WIN1252 characters in the target database.

      and what is the encoding of the data you pass to DBD::Pg when it fails

      Valid UTF-8 Perlstrings with UTF-8 flag turned on.

      and do you have pg_enable_utf8 on?

      No, because from my understanding it is deprecated and only used in reading from the database, not writing to.

        therefore my strong guess that DBIx is logging what gets send to the database

        As the author of DBIx::Log4perl I can guarantee you that DBIx::Log4perl gets any SQL passed to do/prepare before DBI and before DBD::Pg. You seemed to be suggesting that DBD::Pg was changing the encoding on strings and I'm simply saying if it did you would not see this from a DBIx::Log4perl log.

        If you change the encoding of data passed to do/prepare I'd expect the log to change too so that doesn't tell us anything really.

        Looking at the DBD::Pg code, if you don't enable pg_enable_utf8 then it doesn't seem to change any data to or from the database.

        It seems like you are suggesting that when your client chrset is 1252 and you pass UTF8 to DBD::Pg then the data isn't right in the database? I wouldn't expect it to be since postgres thinks it is 1252 but you sent utf8.

        If you have UTF8 encoded data then set your client chrset to utf8. If you want utf8 back then set pg_enable_utf8 - I didn't see a deprecated warning anywhere and I can assure you it is used all over the DBD::Pg code.

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