Re: [PATCH] pg_stat_statements: add last_execution_start column

Hi,

It would be really great to get this field in, but I think the current
implementation still suffers from the same issue that is mentioned
here [1]. We cannot rely on GetCurrentStatementStartTimestamp()
in-line because ExecutorEnd is deferred to the next execution in the
case of extended query protocol. I think we need to add it to track the
start timestamp in queryDesc. What do you think?

```
select pg_stat_statements_reset();

BEGIN;
select now() as now, clock_timestamp() as clock_timestamp,
pg_sleep($1) \bind 10 \g

\! sleep 10

SELECT now() as now, clock_timestamp() as clock_timestamp, $1 \bind 1 \g
END;

select last_execution_start, total_exec_time, substr(query, 1, 150) as
query from pg_stat_statements;
```
Notice how the last_execution_start reflects when the
"SELECT now() as now, clock_timestamp() as clock_timestamp, $1 " runs

--
Sami

[1] [https://www.postgresql.org/message-id/CAA5RZ0sxPWP2xm8fxhscE%2BcUqC2VSFi9UZ9882BdGZ0MbGQNUA%40mail.gmail.com]