On 9-10-2018 16:46, Hugo Eyng [email protected] [firebird-support] wrote: > 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
What version Firebird are you using (full version please), and what is the column type? Mark -- Mark Rotteveel
