| Subject | Very slow select Index with null date |
|---|---|
| Author | Hugo Eyng |
| Post date | 2018-10-09T14:46:40Z |
Hello.
I created an index on a table where de column is datetime type. The problem seems to be related to the NULL value.
This SQL is very SLOW (about 7 seconds for a table containing 360.000 records). Returns around 400 records
SELECT
A.cd_xxx, A.dt_1, A.dt_2, A.dt_3, A.dt_4, A.dt_5, A.dt_index
FROM DM251 A
WHERE A.DT_INDEX IS NULL
This SQL is very FAST (less than 0.5 seconds for a table containing 360.000 records). Returns around 359.600 records
SELECT
A.cd_xxx, A.dt_1, A.dt_2, A.dt_3, A.dt_4, A.dt_5, A.dt_index
FROM DM251 A
WHERE A.DT_INDEX IS NOT NULL
Atenciosamente,
+ + Hugo Eyng + +