How Improve table database design

Question

Im planning my database scheme design for my project website.
This is video table:

In "car" tag page, I retrieve from table in this way (PHP query):

sql = "SELECT * FROM `video` WHERE keyword='car'";
$result = $db->query($sql);
if (!$result) {
}

<?php     while ($row = $result->fetch_assoc()) { ?>

<?php echo  $row['website']; ?><br>

<?php echo  $row['url']; ?><br><br>

<?php } ?>  

This is question: if I store milions of rows in video table, for i.e. 50 milions of rows, is this table scheme design good or I need create something different?

thanks for any suggestion

Answer 1

Good question. Your observation about storing a large number of similar values is valid.

A solution to optimise your design is to use relational table schema. With relational tables, you take common values in fields and move them to another table, then create a link to the table.

As an (unrelated) example, instead of storing the country name in a field a million times, create a field that points to a list of countries. The benefits will be that you will store (a million times) a few bytes for a number compared to (a million times) a few hundred bytes for the name.

The benefits are greater than storage, as it is more efficient to compare numbers than strings. For example, it takes a computer ONE comparison to check if ($val == 10), compared to one check for every letter in a string (imagine running check if ($val = 'a very long string') a million times.

http://en.wikipedia.org/wiki/Relational_database

As an example. assume you have a limited number of keywords.

    CREATE TABLE video
    (
      video_id int(11) NOT NULL auto_increment,
      keyword_id int(11),
      website  varchar(255),
      url   string,
      PRIMARY KEY (video_id)
    );

    CREATE TABLE keywords
    (
     keyword_id int(11) NOT NULL auto_increment,
     keyword_name varchar(255),
     PRIMARY KEY (keyword_id)
    );

Notice that the video table has a field keyword_id, instead of keyword_name, so this will store a number, instead of a string. Examples of your data will be

 - video
id    keyword_id      url
1     1               http://domain1/path1/
2     2               http://domain2/path1/
3     2               http://domain3/path4/
   : 
 - keywords
keyword_id       keyword_name
1                short keyword
2                a long key that has many, many, many characters

If you know the keyword id, then it is easy to search for the videos.

SELECT keyword FROM keywords WHERE keyword_name = 'car';
    : 
SELECT * FROM video where keyword_id = ':keyword_id';

or

SELECT keyword_name, website, url
  FROM video
  JOIN keyword ON keyword_id
 WHERE keyword_name = 'car'

I also came across a few posts on SO.

Relational Database Design Patterns?

Relational Database and Normalization for Relational Tables

Best way with relation tables

Answer 2

With a proper index on the keyword column this design should be fine. But if you intend to be storing such a huge volumes of data in the table, you should definitely consider introducing paging in your SQL queries.