why the sql so slowly?

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now , I need to select a table per minute.
1.
the table struture:
------------------------------------------------------------ -----
CREATE TABLE `table_code` (
`timestamp` timestamp NULL default CURRENT_TIMESTAMP on update
CURRENT_TIMESTAMP,
`code` decimal(5,0) NOT NULL default '0',
PRIMARY KEY (`stock_code`)
)
------------------------------------------------------------ -----
2.
there is a trigger will insert data into the table `table_code`
the trigger is like:
------------------------------------------------------------ -----
if .... then
insert into table_code....
end if;
------------------------------------------------------------ -----
3.
I need to select the table 'table_code' per minute,and the sql is like :
select code from table_code;

now, the problem is:
in normally,the sql executed very fast (0.5-1 second), but sometimes, it
will take more than 3 minutes. I don't know
why? how to find the cause?

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Re: why the sql so slowly?

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How many records are there in this table.
What is the select statement ur running.

regards
anandkl

On Thu, Jun 17, 2010 at 10:05 AM, hewei wrote:

> now , I need to select a table per minute.
> 1.
> the table struture:
> ------------------------------------------------------------ -----
> CREATE TABLE `table_code` (
> `timestamp` timestamp NULL default CURRENT_TIMESTAMP on update
> CURRENT_TIMESTAMP,
> `code` decimal(5,0) NOT NULL default '0',
> PRIMARY KEY (`stock_code`)
> )
> ------------------------------------------------------------ -----
> 2.
> there is a trigger will insert data into the table `table_code`
> the trigger is like:
> ------------------------------------------------------------ -----
> if .... then
> insert into table_code....
> end if;
> ------------------------------------------------------------ -----
> 3.
> I need to select the table 'table_code' per minute,and the sql is like :
> select code from table_code;
>
> now, the problem is:
> in normally,the sql executed very fast (0.5-1 second), but sometimes, it
> will take more than 3 minutes. I don't know
> why? how to find the cause?
>

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Re: why the sql so slowly?

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1.How many records are there in this table.
==>6000 rows.

2.What is the select statement ur running.
==>
-------------------------------
I need to select the table 'table_code' per minute,and the sql is like :
select code from table_code;
-------------------------------

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Re: why the sql so slowly?

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you want to select all rows from the table

On Thu, Jun 17, 2010 at 2:05 PM, hewei wrote:

> 1.How many records are there in this table.
> ==>6000 rows.
>
> 2.What is the select statement ur running.
> ==>
> -------------------------------
>
> I need to select the table 'table_code' per minute,and the sql is like :
> select code from table_code;
> -------------------------------
>

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Re: why the sql so slowly?

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you want to select all rows from the table?

===> YES

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Re: why the sql so slowly?

Try Explain command before execute something
Please google how to use index


----- Original Message -----
From: "hewei"
To: "Ananda Kumar"
Cc: mysql@lists.mysql.com
Sent: Thursday, June 17, 2010 5:54:23 PM
Subject: Re: why the sql so slowly?

you want to select all rows from the table?

===> YES

--
Best Regards,
Cuongmc.

--
Nguyen Manh Cuong
Phong Ky Thuat - Cong ty Vien Thong So - VTC
Dien thoai: 0912051542
Gmail : philipscuong@gmail.com
YahooMail : philipscuong@yahoo.com

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