Hello Masao-san,
>> Maybe. If you cannot check, you can only guess. Probably it should be
>> small, but the current version does not allow to check whether it is so.
>
> Could you elaborate what you actually want to measure the performance
> impact by adding explicit begin and commit? Currently pgbench -i issues
> the following queries. The data generation part is already executed within
> single transaction. You want to execute not only data generation but also
> drop/creation of tables within single transaction, and measure how much
> performance impact happens? I'm sure that would be negligible.
> Or you want to execute data generate in multiple transactions, i.e.,
> execute each statement for data generation (e.g., one INSERT) in single
> transaction, and then want to measure the performance impact?
> But the patch doesn't enable us to do such data generation yet.
Indeed, you cannot do this precise thing, but you can do others.
> So I'm thinking that it's maybe better to commit the addtion of "G" option
> first separately. And then we can discuss how much "(" and ")" options
> are useful later.
Attached patch v6 only provides G - server side data generation.
--
Fabien.