SQL Server Select Query Is Slow

Question

I have approx 820,000 records in my SQL Server table and it is taking 5 seconds to select the data from the table. The table has one clustered index on a time column that could be NULL (as of now it does not contain any NULL value). Why is it taking 5 to 6 seconds to fetch only this much records?

Answer 1

What did you mean by 'select the data'? If you are fetching so many records in management studio (displaying all the records) most of this 6 seconds is consumed by showing you all the rows. If it is the case just insert the records to a temp table. It will be much faster.

Answer 2

I recomend you this:

1.Check if you are using Clustered and Non-Clustered in you columns (best way I think with a sp_help NameTable).
2.When you using comand "select" specific always all name columns (never use Select * From ..... ).
3.If you are using SSMS check in tools SQL Execution Plan , with this tool you can make simple review your TSQL (you can see cost
each query you make.
4.Dont use "convert(...." in clause WHERE , for example .. Where Convert(int,NameColum)=100.