mysql表设计建议

Question

I have a general question about MySQL database table design. I have a table that contains ~ 650 thousand records, with approximately 100 thousand added per year. The data is requested quite frequently, 1.6 times per second on average.

It has the following structure right now

id   port_id         date        product1_price    product2_price    product3_price
 1         1   2012-01-01                100.00            200.00            155.00
 2         2   2012-01-01                  NULL            150.00            255.00
 3         3   2012-01-01                300.00              NULL            355.00
 4         1   2012-01-02                200.00            250.00            355.00
 5         2   2012-01-02                400.00            230.00            255.00

Wouln't it be better to store the data in this manner?

id     port_id         date    product   price
1            1   2012-01-01          1     100
1            2   2012-01-01          1     200
1            3   2012-01-01          1     300
1            1   2012-01-02          1     240

Advantages of the alternative design:

• with the second design we don't have to store NULL values (if there is no such product in the port)
• we can add new products easily - comparing to the first design, where each new product requires a new column

Disadvantages of the alternative design:

• The number of records will increase from 650 000 to 650 000 * number_of_products minus all NULL records; that will be approximately 2.1 million records.

In both cases we have id column as PRIMARY_KEY and UNIQUE key on combination of port_id and date .

So the question is: which way to go? Disk space does not matter, the speed of the queries is the most important aspect.

Thank you for your attention.

Answer 1

It seams, that will depend on definition of product table.
If product table is statically compound of maximum three parts, then changing the current design won't help much.

Although the current design smells bad but that will be a business dependent analysis.
BTW change must be done with caution on the side effects with product table and its usages.