Hi,

Let's take a select:
select * from A where A.id like 'text%'
We know the:
A is indexed on column ID with index T_A_ID
Size of table is 134000 lines

I have the situations:
if text='PH01' there are 1000 lines returned in 1 second (index is used)
if text='PH0' there are 9900 lines returned in 12 seconds (index is not used)
if text='PH0' and add the clause 'with (index (T_A_ID))' to query same 9900 line gets in 2 seconds

Why the engine is not using index in second case and loose performance?

I don't want to write in every select 'with (index...' to optimize the query, it's stupid.

Thanks.