Hello,
I have a table with cca 400,000 rows. The table contains column "key" of varchar(20) type containing 10 distinct values. I want to get out what distinct values are present in the column. I use this simple query, which is very slow:
SELECT DISTINCT Key FROM MRTPContactValue
Here is the query plan:
| QUERY PLAN |
|---|
Unique (cost=64882.26..66964.59 rows=9 width=9) (actual time=26139.972..29593.164 rows=10 loops=1) |
-> Sort (cost=64882.26..65923.43 rows=416466 width=9) (actual time=26139.964..27975.944 rows=416466 loops=1) |
Sort Key: "key" |
-> Seq Scan on mrtpcontactvalue (cost=0.00..8669.66 rows=416466 width=9) (actual time=0.026..2460.535 rows=416466 loops=1) |
| Total runtime: 29603.159 ms |
I've tried index on the "key" column but no improvement.
Is there a way to speed the SELECT up?
Thank you for any suggestions.
--
Miroslav Šulc