Re: [HACKERS] WIP Patch: Pgbench Serialization and deadlock errors

Hello, hackers!

Here there's a seventh version of the patch for error handling and 
retrying of transactions with serialization/deadlock failures in pgbench 
(based on the commit a08dc711952081d63577fc182fcf955958f70add). I added 
the option --max-tries-time which is an implemetation of Fabien Coelho's 
proposal in [1]: the transaction with serialization or deadlock failure 
can be retried if the total time of all its tries is less than this 
limit (in ms). This option can be combined with the option --max-tries. 
But if none of them are used, failed transactions are not retried at 
all.

Also:
* Now when the first failure occurs in the transaction it is always 
reported as a failure since only after the remaining commands of this 
transaction are executed we find out whether we can try again or not. 
Therefore add the messages about retrying or ending the failed 
transaction to the "fails" debugging level so you can distinguish 
failures (which are retried) and errors (which are not retried).
* Fix a report on the latency average because the total time includes 
time for both errors and successful transactions.
* Code cleanup (including tests).

[1] 
https://www.postgresql.org/message-id/alpine.DEB.2.20.1803292134380.16472%40lancre

> Maybe the max retry should rather be expressed in time rather than 
> number
> of attempts, or both approach could be implemented?

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