ZBX-7821 is a great improvement - well, at least when it gets fixed

It would be nice when it will also be possible to optionally make use of the timestamp of the parsed log file as measurement time.

Not well-thought-out but what I currently think of is something like that (just to get the idea):

When two subexpressions are given for log keys with numeric type:

log["/var/log/example.log","^([0-9]{4}-[0-9]{2}-[0-9]{2} [0-9]{2}:[0-9]{2}:[0-9]{2}) txn count: ([0-9]+)",,,,\1 \2]

Then the second subexpression is taken as value and the first subexpression gets converted to timestamp by using a log time format:
Log time format: yyyy-MM-dd hh:mm:ss

Beside having absolutely exact relation between value and time it would allow to parse files with high intervals and still keeping the right time.

Of course, as always one has to keep performance in mind.
Even if it's optionally the conversion might probably be better placed in the agent.