I want to select distinct values from the table

Question

My table has 2 million records. I want to select distinct values from the table. If I use select distinct... it may take more time. What would be another option to select distinct values in less time.

Answer 1

If you've done proper indexing, then SELECT DISTINCT should be the fastest way here.

Answer 2

GROUP BY? or having another table with just distinct values modified by triggers on insert, delete, update to the original table?

Answer 3

If you want to select distinct, you have to select distinct.

Here are few things you can do to make it faster:

1. Index the columns you are selecting distinct upon.
2. Use a clustered index if possible.
3. Partition your data so make searching faster.

2 million rows is big but not at all unheard of for a database.