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;
>>
> Rich,
>
>    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
> ip2number().

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!

Rich

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