Stefan Hinz wrote:
>Sergei,
>
>
>
>>>any other guru who can explain why 10 = 11?
>>>
>>>
>
>
>
>>It's because of NULLs.
>>Extra byte is used to mark, if the column is NULL or not.
>>
>>
>
>Thanks alot for the explanation. Thanks to Gerald Clark, too, who told
>me the same.
>
>
>
>>(in fact it's a bitmap, that is it would be one byte for up to 8
>>columns, then it'll be 2 bytes, etc.)
>>
>>
>
>If so, this table should have an average row length of 92, not 91,
>
It does on mine.
>shouldn't it (9 cols * 10 bytes + 2 bytes)?
>
>MySQL>DESCRIBE myrowisam;
>+-------+----------+------+-----+---------+-------+
>| Field | Type | Null | Key | Default | Extra |
>+-------+----------+------+-----+---------+-------+
>| col1 | char(10) | | | | |
>| col2 | char(10) | | | | |
>| col3 | char(10) | | | | |
>| col4 | char(10) | | | | |
>| col5 | char(10) | | | | |
>| col6 | char(10) | | | | |
>| col7 | char(10) | | | | |
>| col8 | char(10) | | | | |
>| col9 | char(10) | | | | |
>+-------+----------+------+-----+---------+-------+
>MySQL>SELECT * FROM myrowisam;
>+------+------+------+------+------+------+------+------+------+
>| col1 | col2 | col3 | col4 | col5 | col6 | col7 | col8 | col9 |
>+------+------+------+------+------+------+------+------+------+
>| foo | foo | foo | foo | foo | foo | foo | foo | foo |
>+------+------+------+------+------+------+------+------+------+
>MySQL>SHOW TABLE STATUS LIKE 'myrowisam';
>+-----------+--------+------------+------+----------------+
>| Name | Type | Row_format | Rows | Avg_row_length |
>+-----------+--------+------------+------+----------------+
>| myrowisam | MyISAM | Fixed | 1 | 91 |
>+-----------+--------+------------+------+----------------+
>
>Regards,
>--
> Stefan Hinz <hinz@stripped>
> Geschäftsführer / CEO iConnect GmbH <http://iConnect.de>
> Heesestr. 6, 12169 Berlin (Germany)
> Tel: +49 30 7970948-0 Fax: +49 30 7970948-3
>
>----- Original Message -----
>From: "Sergei Golubchik" <serg@stripped>
>To: "Stefan Hinz" <hinz@stripped>
>Cc: "Keith C. Ivey" <keith@stripped>; <mysql@stripped>
>Sent: Thursday, January 16, 2003 9:16 PM
>Subject: Re: Avg_row_length
>
>
>
>
>>Hi!
>>
>>On Jan 16, Stefan Hinz wrote:
>>
>>
>>>Keith,
>>>
>>>thanks once again! Well, anyone here from the MySQL developer team?
>>>
>>>
>Or
>
>
>>>any other guru who can explain why 10 = 11?
>>>
>>>Here's the problem once again:
>>>
>>>mysql> DESCRIBE myrowisam;
>>>+-------+----------+------+-----+---------+-------+
>>>| Field | Type | Null | Key | Default | Extra |
>>>+-------+----------+------+-----+---------+-------+
>>>| col | char(10) | YES | MUL | NULL | |
>>>+-------+----------+------+-----+---------+-------+
>>>mysql> SHOW TABLE STATUS LIKE 'myrowisam';
>>>+-----------+--------+------------+------+----------------+
>>>| Name | Type | Row_format | Rows | Avg_row_length |
>>>+-----------+--------+------------+------+----------------+
>>>| myrowisam | MyISAM | Fixed | 109 | 11 |
>>>+-----------+--------+------------+------+----------------+
>>>
>>>Regards,
>>>--
>>> Stefan Hinz <hinz@stripped>
>>> Gesch?ftsf?hrer / CEO iConnect GmbH <http://iConnect.de>
>>> Heesestr. 6, 12169 Berlin (Germany)
>>> Tel: +49 30 7970948-0 Fax: +49 30 7970948-3
>>>
>>>
>>It's because of NULLs.
>>Extra byte is used to mark, if the column is NULL or not.
>>
>>(in fact it's a bitmap, that is it would be one byte for up to 8
>>columns, then it'll be 2 bytes, etc.)
>>
>>Regards,
>>Sergei
>>
>>--
>>MySQL Development Team
>> __ ___ ___ ____ __
>> / |/ /_ __/ __/ __ \/ / Sergei Golubchik <serg@stripped>
>> / /|_/ / // /\ \/ /_/ / /__ MySQL AB, http://www.mysql.com/
>>/_/ /_/\_, /___/\___\_\___/ Osnabrueck, Germany
>> <___/
>>
>>
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