Re: WIP Patch: Pgbench Serialization and deadlock errors

Hello everyone!

There's the second version of my patch for pgbench. Now transactions
with serialization and deadlock failures are rolled back and retried
until they end successfully or their number of attempts reaches maximum.

In details:
- You can set the maximum number of attempts by the appropriate
benchmarking option (--max-attempts-number). Its default value is 1
partly because retrying of shell commands can produce new errors.
- Statistics of attempts and failures is printed in progress, in
transaction / aggregation logs and in the end with other results (all
and for each script). The transaction failure is reported here only if
the last retry of this transaction fails.
- Also failures and average numbers of transactions attempts are printed
per-command with average latencies if you use the appropriate
benchmarking option (--report-per-command, -r) (it replaces the option
--report-latencies as I was advised here [1]). Average numbers of
transactions attempts are printed only for commands which start
transactions.

As usual: TAP tests for new functionality and changed documentation with
new examples.

Patch is attached. Any suggestions are welcome!

[1]
https://www.postgresql.org/message-id/alpine.DEB.2.20.1707031321370.3419%40lancre

--
Marina Polyakova
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company