pgbench - allow to store select results into variables

Fabien COELHO <coelho@cri.ensmp.fr>

From: Fabien COELHO <coelho@cri.ensmp.fr>

To: PostgreSQL Developers <pgsql-hackers@postgresql.org>

Date: 2016-07-09T08:20:39Z

Lists: pgsql-hackers

Attachments

pgbench-into-1.patch (text/x-diff) patch
into.sql (application/x-sql)
into-err-1.sql (application/x-sql)
into-err-2.sql (application/x-sql)
into-err-3.sql (application/x-sql)
into-err-4.sql (application/x-sql)
into-err-5.sql (application/x-sql)
into-err-6.sql (application/x-sql)

Hello devs,

I mentionned my intention to add some features to pgbench back in March:
https://www.postgresql.org/message-id/alpine.DEB.2.10.1603301618570.5677@sto

The attached patch adds an \into meta command to store results of 
preceding SELECTs into pgbench variables, so that they can be reused 
afterwards.

The feature is useful to make more realistic scripts, currently pgbench 
script cannot really interact with the database as results are discarded.

The chosen syntax is easy to understand and the implementation is quite 
light, with minimal impact on the code base. I think that this is a 
reasonnable compromise.

The SELECTs must yield exactly one row, the number of variables must be 
less than the number of columns.

Also attached a set of test scripts, especially to trigger various error 
cases.

-- 
Fabien.

Commits

pgbench: Remove \cset
- 25ee70511ec2 12.0 landed
pgbench: add \cset and \gset commands
- 6260cc550b0e 12.0 landed
Adjust pgbench to allow non-ASCII characters in variable names.
- 9d36a386608d 11.0 landed
Refactor script execution state machine in pgbench.
- 12788ae49e19 10.0 cited
Allow empty queries in pgbench.
- 6471045230f5 10.0 cited