Need to use indexes in SELECT * without using where, How to do that ?

2CODE

Hello,

I've a table like that

Table name : table1

a_id,a_name,a_code,a_number,a_date,a_type,a_quant,a_by

And I use indexes in (a_name,a_id (Primary key), a_code,a_number)

Now I want to make select * from table1 to get all of the data

However no indexes are use in explain query, How I can tell the query to use index without using the where clause for sure as I don't want to specific the values.

Also I tried use index and force index and nothing changed 🙁

Weedpacket

There's no point using an index because the entire table will have to be scanned anyway.

2CODE

I also tried to specific the select query (selecting about 70% of the table) and also no luck, No way to get a key appears in the explain.

Also tried the force index and use index after specific the query data.

Any suggestions ? I've made the query more specific by selecting some columns however I also can't get an index to be used in the query.

NogDog

It might help to see some examples of the queries, but as stated in the first reply: if you don't have a where clause, then no indexes will be used. Even if you have a where clause, index usage isn't guaranteed, depending on what is in that where clause, or at least an order by on and indexed column. (E.g.: if your where clause would select 70% of the records, the DBMS may decide it can actually run faster by just reading all the rows anyway, rather than doing index processing.)

Weedpacket

2CODE wrote:
I've made the query more specific by selecting some columns however

Columns or rows? Restricting which columns are selected wouldn't make a difference because you'd still be scanning every row in the table.