Have a strange problem.
A large table (>1tb), select statement of a number of columns return about 30 rows.
Key is a combination of a timestamp and an string id.
I put MAX on those columns and one of the columns causes a time out.
Have isolated this to one particular column.
MIN also gives a timeout but AVG works.
The other columns works ok.
In another database with an identical table (but not that large) it works ok.
Any ideas will be much appreciated
What is the query that returns 30 rows look like for example the where clause
select MAX(EP_COMP) AS EP_COMP
and [SMPTIME] > '2018-11-20 16:00:00'
and [SMPTIME] < '2018-11-20 17:00:00';
If I change to AVG or SUM it works ok, also with other columns (also float columns)
MAX() would require a sort, AVG and SUM would not.
Can you post the table definition, CREATE TABLE ..., including all indexes.
What happens if you try this
select MAX(EP_COMP) AS EP_COM
Where [PAID]='003411' and [SMPTIME] > '2018-11-20 16:00:00' and [SMPTIME] < '2018-11-20 17:00:00') big