How to avoid the query using the index?

Question

select *from cstb_cut ;
cust_id      cust_name
10001        xxxx
10002        yyyy
10003        zzzz
Please find the above table and 10000 records are there in that table and also one index was there on cust_id.
but my query don't want to use the index?how it will be done?

Answer 1

Hi,
DEVI suvarna wrote:
select *from cstb_cut ;
cust_id      cust_name
10001        xxxx
10002        yyyy
10003        zzzz
Please find the above table and 10000 records are there in that table and also one index was there on cust_id.
but my query don't want to use the index?how it will be done?
The index doesn't help for this query, so it's not used.
The main purpose of indexes is the help find a small number (like 1) of rows quickly.  You're asking for all rows; getting each one through the index would be slower than just getting all of them directly.
Sometimes (but not here) the index can be used instead of the table, when the index contains all the data you need from the table.  An index on cust_id doesn't tell you anything about any other column, such as cust_name.  Since you asked to have all columns displayed, it has to fetch data from the table, not the index.