The fastest way to fetch data from the database using codeigniter

Question

There is a table of communications which contains IDs of content and the corresponding keys. It is necessary to organize fast search for a filtration in keys. If value of a key equally to null, approaches any content. For example, if the post inquiry comes $ _POST == array (filter1 => 2, filter2 => 4, filter3 => 2, filter4 => null) , then result will be the array(content_ids => array(4, 7))

id | content_id | filter1| filter2 | filter3 | filter4
1 | 1 | 1 |3 |1 |NULL
2 | 2 | 2 |6 |2 |2
3 | 3 | 1 |5 |1 |NULL
4 | 5 | 1 |1 |1 |5
5 | 4 | 2 |4 |2 |7
6 | 6 | 2 |2 |2 |NULL
7 | 7 | 2 |4 |NULL |NULL

PS: The table will contain thousands of lines, and the number of filters will be equal 12

Answer 1

IMHO the question is more about SQL rather than Codeigniter.

What you can do is to build the query that looks like

SELECT content_id
  FROM table1
 WHERE (? IS NULL OR filter1 = ? OR filter1 IS NULL)
   AND (? IS NULL OR filter2 = ? OR filter2 IS NULL)
   AND (? IS NULL OR filter3 = ? OR filter3 IS NULL)
   AND (? IS NULL OR filter4 = ? OR filter4 IS NULL)

where ? are placeholder for actual filter values that you get via POST .

Output with your sample data:

| CONTENT_ID |
|------------|
|          4 |
|          7 |

Here is SQLFiddle demo

Consider creating a covering index or indices (depending on actual data access patterns) for performance reasons.