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Re: Which one is faster?

From: Ed prochak <ed.prochak_at_magicinterface.com>
Date: 7 Jul 2004 12:39:01 -0700
Message-ID: <4b5394b2.0407071139.3a441a1@posting.google.com>


"Oracle Newbie" <f93c0532_at_yahoo.com> wrote in message news:<2l1dfuF7cgu4U1_at_uni-berlin.de>...
> "Sybrand Bakker" <sybrandb_at_hccnet.nl> wrote in message
> news:phvme0p53ds1h41i8efbgmlqjqj034d6pq_at_4ax.com...
> > On Wed, 7 Jul 2004 09:32:24 +0500, "Oracle Newbie"
> > <f93c0532_at_yahoo.com> wrote:
> >
> > >I have a string of thousands of characters and I want to check if it ends
> > >with '>>' There are 2 ways of doing it ( or more maybe)
> > >
> > >If big_str like '%>>' Then
> > >
> > >OR
> > >
> > >If substr(big_str , length(big_str) - 1 , 2 ) = '>>' Then
> > >
> > >Which one is faster? obviously the 1st one is simpler.
> > >
> > >Or is there a better way?
> > >
> > >thx
> > >
> >
> > The second looks faster to me.
>
> Why? ( esp. when it contains two functions )

while the first one results in a state machine, it has to search the string (ie check each character) from the beginning. The function-based one merely counts the characters.
>
> > BTW: any reason you didn't try it yourself?
>
> How can I test for speed? I'm using Toad 7.6
>
> thx
> > --
> > Sybrand Bakker, Senior Oracle DBA

The real question is: why do you care about the speed?

I suggest you learn to write queries that produce the right answers before concerning yourself with performance issues. No matter how fast the wrong answer comes back, it's still wrong.

HTH,
   ed Received on Wed Jul 07 2004 - 14:39:01 CDT

Original text of this message

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