Re: Function in WHERE performance issue
Date: Mon, 13 Jul 2009 10:25:32 -0500
The only concern I'd have with Dan Tow's solution for Oracle -- adding AND ROWNUM=1 -- is that it doesn't shortstop the range scan in a not-found condition, which can definitely happen in the original data set. The nested subquery solution I posted before does.
Rerunning the earlier query I had for 184.108.40.206 (which isn't in the data set):
with rownum = 1, no subquery - 28109 CG's
with rownum = 1, with subquery - 6 CGs
without rownum = 1, with subquery - 6 CGs
It's an 8.8 million row IOT I'm searching, so telling it to stop when it can't find a match anymore is an excellent idea. I think it should be able to stop once the search_ip > end_ip, but it doesn't seem to on its own.
On Mon, Jul 13, 2009 at 9:30 AM, Bobak, Mark<Mark.Bobak_at_proquest.com> wrote:
> I had a similar problem a while back. Dan Tow provided me an excellent solution, and also wrote it up as an articel, here:
> I think it's worth your time to read.
> From: oracle-l-bounce_at_freelists.org [oracle-l-bounce_at_freelists.org] On Behalf Of Rich Jesse [rjoralist_at_society.servebeer.com]
> Sent: Monday, July 13, 2009 10:25
> To: Oracle L
> Subject: Re: Function in WHERE performance issue
> Hey Stephane,
>>> select /*+ first_rows(1) */ aa.*
>>> from geo_location aa,
>>> geo_blocks b
>>> where aa.locid = b.locid
>>> and ip2number('192.168.1.1') between b.startipnum and b.endipnum;
>> It's a question of bounds.
>> Just add the additional condition
>> and b.startipnum >= to_number(substr('&ip_addr', 1,
>> instr('&ip_addr'), '.') - 1)) * 16777216
>> and you should feel the difference. No need to create a FBI on
> But I haven't created an FBI. And while the addition of the above to the
> WHERE clause does cause a sub-second return, reworking the statement to:
> select /* first_rows(1) */ aa.*
> from geo_location aa,
> geo_blocks b
> where aa.locid = b.locid
> -- and ip2number(:p_ipaddr) between b.startipnum and b.endipnum
> and to_number(substr(:p_ipaddr, 1,instr(:p_ipaddr, '.') - 1)) * 16777216
> between b.startipnum and b.endipnum
> ...does not. While somewhat faster at ~5s, it's not sub-second.
>> And, please, remove the hint, it's ugly.
> I'd love to. I only have one hint on one query on this system and it's for
> an outline. However, without the hint I get an FTS, which I know isn't
> necessary, based on the sub-second response times I can get by changing the
> predicate. Removing it would certainly be ideal.
> I'll probably be running this statement in PL, where I can parse the IP via
> the function and then pass the result to the SQL via bind, so my question is
> more academic. But I'm having a mental issue of generalizing the situation
> so that I can apply it to other future issues like this.
> Thanks for the ideas!
-- Adam Musch ahmusch_at_gmail.com -- http://www.freelists.org/webpage/oracle-lReceived on Mon Jul 13 2009 - 10:25:32 CDT