Re: proposal: prefix function

pá 21. 9. 2018 v 12:37 odesílatel Chris Travers <chris(dot)travers(at)adjust(dot)com>
napsal:

>
>
> On Fri, Sep 21, 2018 at 10:09 AM Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
> wrote:
>
>> Hi
>>
>> can we implement prefix function for fast test if substr is prefix of
>> some string?
>>
>> create or replace function prefix(str text, substr text)
>> returns boolean as $$
>> select substr(str, 1, length(substr)) = substr
>> $$ language sql;
>>
>> This function can be very effective in C language. Now it should be
>> implemented with like or regexp, what is significantly more expensive.
>>
>>
> These would just be wrappers around already existing internal functions,
> right?
>

maybe, I didn't do any research. If not, the implementation is on few lines.

Regards

Pavel

>
>
>> Regards
>>
>> Pavel
>>
>
>
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> Best Regards,
> Chris Travers
> Head of Database
>
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