Generating Bulk of Data for Testing Purpose

Sometimes we need to generate a huge amount of data to perform some testing. Type of data to be generated depends on the scenario you want to test. I will show here a very simple example to create a very huge table. I usually use it if I need to have a huge tablespace or table to perform some test. For example, to test backup
and recovery time of some tablespace with huge data, I would use this method to generate huge data

C:\>sqlplus "/ as sysdba" SQL*Plus: Release 12.1.0.2.0 Production on Tue Jul 21 09:41:59 2015 Copyright (c) 1982, 2014, Oracle.  All rights reserved. Connected to: Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options SQL> create tablespace my_tbs datafile 'c:\my_tbs01.dbf' size 100m autoextend on next 100m; Tablespace created. 10:27:33 SQL> create table test as select * from dba_objects; Table created. Elapsed: 00:00:00.89 10:27:55 SQL> alter table test move tablespace my_tbs; Table altered. Elapsed: 00:00:00.74 --Delete NULL from OBJECT_ID column if you want to test primary key index on this column. 10:28:08 SQL> delete from test where object_id is null; 1 row deleted. Elapsed: 00:00:00.20 10:28:17 SQL> commit; Commit complete. Elapsed: 00:00:00.00 --Repeat INSERT statement to insert TEST table’s data into itself to increase size by 2X with every insert. 10:28:18 SQL> insert into test select * from test; 91122 rows created. Elapsed: 00:00:00.17 10:28:22 SQL> insert into test select * from test; 182244 rows created. Elapsed: 00:00:00.61 10:28:25 SQL> insert into test select * from test; 364488 rows created. Elapsed: 00:00:03.35 10:28:29 SQL> insert into test select * from test; 728976 rows created. Elapsed: 00:00:07.78 10:28:38 SQL> insert into test select * from test; 1457952 rows created. Elapsed: 00:00:23.11 10:29:02 SQL> insert into test select * from test; 2915904 rows created. Elapsed: 00:00:43.86 10:29:47 SQL> insert into test select * from test; 5831808 rows created. Elapsed: 00:02:10.51 10:31:59 SQL> insert into test select * from test; 11663616 rows created. Elapsed: 00:04:14.96 10:36:20 SQL> commit; Commit complete. Elapsed: 00:00:00.02 --Check size of table and tablespace after having more than 200 million rows in TEST table 10:36:20 SQL> select bytes/1024/1024 from dba_data_files where tablespace_name='MY_TBS'; BYTES/1024/1024 ---------------            3100 Elapsed: 00:00:00.08 10:36:49 SQL> select bytes/1024/1024 from dba_segments where segment_name='TEST'; BYTES/1024/1024 ---------------            3079 Elapsed: 00:00:00.33 10:37:10 SQL> select count(*) from test;   COUNT(*) ----------   23327232 Elapsed: 00:00:30.59 10:37:52 SQL>