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Re: IB: trx_t:: start_time and start_time_micro


Hi Aleksey,

I think that we should remove trx_t::start_time, and always use

I shortly discussed this with Vladislav Vaintroub, and he mentioned that
the microsecond timestamp in THD::start_utime is updated at the start of
each statement.
I also looked at his MDEV-12345 performance fix
It looks like trx_start_low() is already doing the right thing, except that
the trx_t::start_time should be removed.

I'd welcome a contributed patch that removes trx_t:.start_time. Or if that
really is too tricky, convert start_time_micro to start_time.


On Thu, Nov 16, 2017 at 11:29 AM, Aleksey Midenkov <midenok@xxxxxxxxx>

> Hello!
> Different semantics of these 2 members doesn't look good:
> time_t start_time; /*!< time the state last time became
> ib_uint64_t start_time_micro; /*!< start time of transaction in
> microseconds */
> Either `start_time_micro` should be drawn to the base of `start_time`
> or it should be explicitly commented that it has nothing to do with
> `start_time`. I.e. there is nothing wrong on algorithmic level, but
> such data members may (and certainly would) lead developers to misuse
> of `start_time_micro`.
> --
> All the best,
> Aleksey Midenkov
> @midenok
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Marko Mäkelä, Lead Developer InnoDB
MariaDB Corporation



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