pgbench在9.3中的一个改动

PostgreSQL v9.2及之前版本中：

• -s scale_factor

• Multiply the number of rows generated by the scale factor. For example, -s 100 will create 10,000,000 rows in the pgbench_accounts table. Default is 1.

PostgreSQL v9.3中：

• -s scale_factor

• Multiply the number of rows generated by the scale factor. For example, -s 100 will create 10,000,000 rows in the pgbench_accounts table. Default is 1. When the scale is 20,000 or larger, the columns used to hold account identifiers (aid columns) will switch to using larger integers (bigint), in order to be big enough to hold the range of account identifiers.

v9.3中支持初始化数据量scale>=20000，即2000000000条数据，相应的aid字段类型将会由intger被更改为bigint以支持大数据量。