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RE: [INTERFACES] JDBC and character sets

From: Peter Mount <petermount(at)it(dot)maidstone(dot)gov(dot)uk>
To: "'t-ishii(at)sra(dot)co(dot)jp'" <t-ishii(at)sra(dot)co(dot)jp>, David Warnock <david(at)sundayta(dot)co(dot)uk>
Cc: pgsql-interfaces(at)postgresql(dot)org
Subject: RE: [INTERFACES] JDBC and character sets
Date: 1999-06-22 15:08:37
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-interfaces
If I understand this correctly, if I make sure the driver converts the
strings (in the correct methods) into UTF-8, then unicode support will

I'm wondering, as I haven't delved into Unicode with the driver yet. If
this is the case, it will be a simple thing to implement.


Peter Mount
Enterprise Support
Maidstone Borough Council
Any views stated are my own, and not those of Maidstone Borough Council.

-----Original Message-----
From: Tatsuo Ishii [mailto:t-ishii(at)sra(dot)co(dot)jp]
Sent: Tuesday, June 22, 1999 3:14 PM
To: David Warnock
Cc: t-ishii(at)sra(dot)co(dot)jp; pgsql-interfaces(at)postgreSQL(dot)org
Subject: Re: [INTERFACES] JDBC and character sets 

>I think I saw from the list of developers that you wrote a lot of the
>multiu-byte code. Is that correct? If so my grateful thanks.

Yes, I'm responsible for the code multi-byte.

>Are there any limitations or gotchas about using unicode everywhere?
>1. Column length. Is this measured in unicode characters or do I need
>increase the length of Varchars? ie is a varchar(10) certain to hold 10
>unicode characters?

When you define varchar(n), n should be counted in bytes, not
We assume Unicode is input as UTF-8 encoding. In UTF-8, 10 ASCII chars
take 10 bytes. So varchar(10) will hold 10 Unicode chars if they are
all ASCII. However, if you use ISO8859 chars they will take 2 bytes
for each letter. If you use KANJI, 3 bytes for each letter. You could
use octet_length() to measure the size of a Unicode string in bytes.

>2. Indexing. What sort order will I get from an index or an order by
>unicode characters.

It will sorted in the order of Unicode code point.

>Can this be customised.

Currently no.

>Generally I try to do any
>really important sorting in Java where I can use the correct sort order
>for the locale.

>3. Upper/lowercase. I have been using separate columns for uppercase
>versions of names etc again so that the case changes can be done by the
>client which will know the correct rules for the locale where the data
>is entered. What do upper/lower case functions in Postgresql do with

I think it will related to locale. I'm not sure but I've heard about
Unicode locale. If it really exists, you could do:

configure --with-mb=UNICODE --with-locale

so that upper/lower works for Unicode.

>4. Are there any limitations on what I use to write triggers? Can all
>the different ways work reliably with unicode?

I'm not sure but it should work with triggers.
Tatsuo Ishii


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Subject: Re: [INTERFACES] JDBC and character sets
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