Re: to_date_valid()

2016-07-05 4:33 GMT+02:00 David G. Johnston <david(dot)g(dot)johnston(at)gmail(dot)com>:

> On Mon, Jul 4, 2016 at 8:39 PM, Andreas 'ads' Scherbaum <
> adsmail(at)wars-nicht(dot)de> wrote:
>
>> On 04.07.2016 18:37, Pavel Stehule wrote:
>>
>>>
>>> I don't know if the name "strict" is best, but the name "validate" is
>>> not good too. Current to_date does some validations too.
>>>
>>
>> Obviously not enough, because it allows invalid dates. I'd say that the
>> current to_date() merely validates the input format for string parsing, and
>> that the date is in range. But there is not much validation on the date
>> itself.
>>
>> So the name can't be "strict" because of the conflict with "NULL"
>> handling, and you don't like "valid" - what other options do you offer?
>
>
> ​We don't have to change the name...we could do something like how
> RegularExpressions work - like (?i) - and just add a new modifier ​code.
>
> ​'~YYYY-MI-DD' --that's a leading tilde, could be anything - even
> something like "HMYYYY-MI-DD" for "historical mode"
>
> ​Also, see this thread of a few weeks ago for related material:
>
>
> https://www.postgresql.org/message-id/1873520224.1784572.1465833145330.JavaMail.yahoo%40mail.yahoo.com
>
> It seems that fixing it is back on the table, possibly even for 9.6 since
> this is such a hideous bug - one that closely resembles a cockroach ;)
>
> WRT to the 2014 "reject out-of-range dates" thread, I'm kinda surprised
> that we didn't just set the date to be the minimum or maximum allowable
> date back in 9.2 instead of rejecting it...
>
> I'd be more inclined to add another argument if it was basically an enum.
>
> to_date(text, format, format_style)
>
> This at least opens the door for future enhancements that are associated
> with named styles. I could imagine an "exact" format that also allows for
> something like regexp character classes so that one can write:
> "YYYY[:SEP:]MM[:SEP:]DD" to keep exact matches but accommodate variations
> on what people type as a separator e.g. [.-/]
>
> format_style=>historical would invoke today's behaviors
>

this is compatibility break - the question is "can we break it?"

Pavel

>
> David J.
>
>