maria-discuss team mailing list archive

[Peter Laursen <peter_laursen@xxxxxxxxxx>]

That is fine then!  Only a little confusing thing is that as far as I know
TIMESTAMP(14) is supported in MySQL 5.1 (and abandoned in MySQL 5.5) - so
probably still in MariaDB as well.  So maybe N should rather have been 17 or
20 (the byte length)?

-- Peter

On Wed, Sep 21, 2011 at 16:39, Philip Stoev <pstoev@xxxxxxxxxxxx> wrote:

> Hello,
>
> By default, the existing precision is used. Only if a column is defined as
> TIME|TIMESTAMP(N) with N being either 3 or 6 , then millisecond or
> microsecond precision will be used.
>
> Philip Stoev
>
> ----- Original Message ----- From: "Peter Laursen" <
> peter_laursen@xxxxxxxxxx>
>
> To: <maria-discuss@xxxxxxxxxxxxxxxxxxx>; <
> maria-developers@xxxxxxxxxxxxxxxxxxx>
> Sent: Wednesday, September 21, 2011 5:33 PM
> Subject: [Maria-developers] Microseconds support in MariaDB 5.3.
>
>
>
>  I noticed: http://askmonty.org/blog/the-2-year-old-mariadb/ "The support
>> for
>> microseconds in TIMESTAMP, DATETIME, and TIME".
>>
>> I fully agree the 'full seconds support only' has been a sever limitation
>> in
>> MySQL. But I have two concerns with ths:
>>
>> 1)
>> 'noisyness'. On not very fast systems the last digits of a TIME in
>> microseconds should not be considered too much important.  It depends on
>> what else the system is doing at the time. I think for lots of users
>> milliseconds and not microseconds would be better/more relevant.  It is
>> not
>> always a lot of digits can be proven true.  When we went to school we were
>> all taught not to present results in natural sciences more accurate than
>> the
>> accuracy of data sources and measurements. Providing too many digits in a
>> resuslt actually caused a lower score in my highschool!
>>
>> 2)
>> Compability.  There is a problem with UPDATES. A client/application
>> written
>> for MySQL may assume 'full seconds support only' and may generate the
>> current MySQL format byte format in the WHERE clause (typically if the
>> client reserves a 14 byte buffer for TIMERSTAMPS etc).  In SQL:
>>
>> UPDATE table SET column = 'something' WHERE  time_column = '01:01:01':
>> .. this update will fail if the currently stored value is
>> '01:01:01:010001'; and the rigth query in the context would be.
>> UPDATE table SET column = 'something' WHERE  time_column =
>> '01:01:01:010001';
>>
>>
>> Ideally I think there should be a configuration parameter and a global
>> variable to SET time_accuracy = full_second|millisecond|microsecond.
>>
>>
>> Did somebody have considerations about same? I definitely think that lots
>> of
>> applications using a TIME|TIMESTAMP|DATETIME column in the WHERE-clause of
>> an UPDATE statement will need some rewrite to be upgradable to MariaDB 5.3
>>
>>
>> -- Peter
>>
>>
>
>
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