CREATE TABLE smalltable AS SELECT rownum AS num, dbms_random.string('A', 100) AS str FROM (SELECT 0 FROM dba_objects WHERE rownum <= 1000); SELECT TO_CHAR(bytes / 1024 / 1024, '9,999,990.900') AS "MB" FROM user_segments WHERE segment_name = 'SMALLTABLE'; CREATE TABLE bigtable AS SELECT t1.num * 1000000 + t2.num * 1000 + t3.num AS num, t1.str AS str1, t2.str AS str2, t3.str AS str3 FROM smalltable