Subject Re: [ib-support] Re: Key size
Author Ann W. Harrison
At 12:44 PM 3/20/2002 +0000, ibfa2000 wrote:
>As far as I know, 255 bytes (and not 255 characters).
>
>This means :
>
>- 255 chars if you use 1-bytes chars (like charset ASCII or ISO8859_1)
>- 127 chars if you use 2-bytes chars (like charset BIG_5)
>- 84 chars if you use 3-bytes chars (like charset UNICODE_FSS)

The situation is worse than that. If you use a non-binary collating
sequence - one that sorts upper and lower case in a rational fashion,
for example, you increase the key representation. If you use a
collating sequence that includes fancy things like diacritical marks,
you increase the key representation again. So even if you use a
one byte character set, you will be limited to 84 characters if you
specify a collating sequence like FR-FR.

And it's worse than that, still. If you have a compound key, each
key is rounded up to five bytes and a tag bit is included every five
bytes.


Regards,

Ann
www.ibphoenix.com
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