At 9:47 AM -0500 5/26/99, A. Brandic wrote:
>My view was that if you use a CHAR rather than a VARCHAR, execution of a
>query is faster. Is this true, and how much faster?
>I've done some test on a few tables with 15 coulms and 15000 rows (simple
>selects and Joins) and there was a difference. I guess on bigger DBs the
>difference will be greter? Am I right (or left:)).
I'm not really sure. But you should be able to keep your table from
turning into a varible length table by creating it like this:
create table Tab1 (
Code CHAR(8),
Bank CHAR(40),
Method CHAR(2),
Name CHAR(40)
);
That way, you won't have any VARCHAR columns, and MySQL won't mess
with your definition. :-)
>
>Ajdin
>
>
>On Wed, 26 May 1999, Paul DuBois wrote:
>
>> At 8:49 AM -0500 5/26/99, kai@stripped wrote:
>> >>Description:
>> >The output of a
>> > show columns from TABLE
>> >command has problems with CHAR and VARCHAR columns. The script in the next
>> >section produces the following output:
>> >
>> >Field Type Null Key Default Extra
>> >Code varchar(8) YES NULL
>> >Bank varchar(40) YES NULL
>> >Method char(2) YES NULL
>> >Name varchar(40) YES NULL
>> >
>> >Each VARCHAR column was created as a CHAR column, and the CHAR column was
>> >created as a VARCHAR column.
>> >
>> >>How-To-Repeat:
>> >Execute the following script:
>> >
>> >#!/bin/bash
>> >set +x
>> >
>> >mysql -u root <<EOF
>> >
>> >drop database if exists bug;
>> >create database bug;
>> >use bug;
>> >
>> >create table Tab1 (
>> > Code CHAR(8),
>> > Bank CHAR(40),
>> > Method VARCHAR(2),
>> > Name CHAR(40)
>> >);
>> >
>> >show columns from Tab1;
>> >EOF
>> >
>> >>Fix:
>> > ???
>>
>>
>> MySQL silently changes CHAR(N) to VARCHAR(N) for N>=4 if you have any
>>VARCHAR
>> columns since by including such columns in your table, the records become
>> variable-length anyway.
>>
>> Reference:
>>
>>http://www.mysql.com/Manual_chapter/manual_Reference.html#Silent_column_changes
>>>>
>> --
>> Paul DuBois, paul@stripped
>> Northern League Chronicles: http://www.snake.net/nl/
>>
>> ---------------------------------------------------------------------
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--
Paul DuBois, paul@stripped
Northern League Chronicles: http://www.snake.net/nl/
