I have a table (T1) with ca. 500000 records:

```
    ID1    Relation  ID2
    4      Rel41      3
    5      Rel21      7
    13     Rel2       4

```

What is the efficient way to retrieve the records that the value 4 exist in:

The result should be: 

```
 4 Rel41 3
 13 Rel2 4  

```

I tried multiple-column index as follows:

```
create table T1 (
    ID1 varchar(5), 
    Relation varchar(50), 
    ID2 varchar(5), 
    PRIMARY KEY (ID1,ID2)
); 

```

and then I used select statement as follows:

```
 select * from T1 WHERE ID1=4 OR ID2=4 ;

```

This was even slower than using no multiple-column index.

which type of index should be used here?