Setting SIZE SIZE should be set to the average amount of space required to hold all rows for any given hash key. If the hash cluster is to contain multiple tables, SIZE can be set to the average amount of space required to hold all rows associated with a representative hash value. If you expect frequent collisions on inserts, the likelihood of overflow blocks being allocated to store rows is high. To reduce the possibility of overflow blocks and maximize performance when collisions are frequent, you should increase SIZE as shown in the following chart. You decide to load the EMP table into a hash cluster.
Most queries retrieve employee records by their employee number.
You estimate that the maximum number of rows in the EMP table at any given time is 10000 and that the average row size is 55 bytes. Since this column contains integers that are unique, the internal hash function can be bypassed. In this case, however, rows are usually retrieved by department number. At most, there are 1000 departments with an average of 10 employees per department. Since this column contains integers that are uniformly distributed, the internal hash function can be bypassed.