Consider a table products which has product details including its category. One product may belong to multiple category so I’m keeping it as a comma separated list of category IDs.
I know this is not normalized approach.
Can any MYSQL expert tell me that which approach will be faster for selecting products of a particular category.
Obviously we have to JOIN products table and products_category_relation table if take normalized approach.
AND
In my approach we have to write a like query to find the products (assume we are searching for category id 10)
SELECT p.*
FROM products p
WHERE p.category like '10'
OR p.category like '10,%'
OR p.category like '%,10'
OR p.category like '%,10,%'
Can any one tell me if this approach is faster or the JOIN approach will be faster?
I know about normalization. I know about other risks involved in my approach. But they do not matter in my case. So, I’m concerned with speed.
Any theoretical explanation about its speed or a practical test result are welcome.
UPDATE
I’m using myISAM engine
product table has Primary Key product_id
FullText index on category column of products table
A database conforming to the first normal form will be much faster. Your example query cannot use any index and requires a full table scan to resolve. Worse, it must scan the entire text field for all the rows and text work is almost always more expensive than integer work for the computer.
A normalized table can easily use an index on the category column to speed up the query.
Text storage may also require more space on disk since numbers are usually more expensive when saved as characters than as the correct integer type (of course there’s some overhead involved in row storage as well).