pá 21. 9. 2018 v 12:37 odesílatel Chris Travers <chris.trav...@adjust.com> napsal:
> > > On Fri, Sep 21, 2018 at 10:09 AM Pavel Stehule <pavel.steh...@gmail.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 >> > > > -- > Best Regards, > Chris Travers > Head of Database > > Tel: +49 162 9037 210 | Skype: einhverfr | www.adjust.com > Saarbrücker Straße 37a, 10405 Berlin > >
