Re: Underlying Implementation of VARCHAR data types

From: Tanel Põder <change_to_my_first_name_at_integrid.info>
Date: Sat, 24 Apr 2004 10:05:39 +0300
Message-ID: <408a11c4$1_1@news.estpak.ee>

> I know for table t there are 3 bytes(fb, lb, cc) overhead in row
> header, so I get the conclusion
> that value length <= 250, the overhead is 1, value length > 250, the
> overhead is 3. Char type has
> same behavior.
>
> I did this test on 9.2.0.3.
>
> Please let me know if something wrong in my test.

Nothing wrong in the test, with column length > 250 the first byte's value is 254 (or was it 253) and from that Oracle understands that the column length is stored in next 2 bytes. But with shorter columns, only one byte is used for length.

Tanel. Received on Sat Apr 24 2004 - 02:05:39 CDT