Because the RANDOM function is evaluated for each selected row, a condition on an index column that includes the RANDOM function results in an all-AMP operation.
For example, consider the following table definition:
CREATE TABLE t1 (c1 INTEGER ,c2 VARCHAR(9)) PRIMARY INDEX ( c1 );
The following SELECT statement results in an all-AMP operation:
SELECT * FROM t1 WHERE c1 = RANDOM(1,12);