Re: [SQL] query speed joining tables

[Tomasz Myrta]

Christopher Smith wrote:

>my mistakes, zips_max should be zips_300.
>and
>in my zip code table there are 120 million rows, example of the records >are
>
>origin destination
>===================
>
>90210 90222
>90210 90234
>90210 96753


1.try to create index on both fields on zips_300 - origin and destination
zips_300_ind(origin,destination)
2.if you have only unique pairs in zips_300, this query should noticable speed up you example:

select userid
from
user_login UL
join user_details_p UD using (userid)
join user_match_details UM using (userid)
join zips_300 Z on (Z.destination=UM.zipcode and Z.origin='90210')
where
UD.gender ='W' AND
UD.seekgender ='M' AND
UD.age between 18 and 50 and
UMD.min_age <= 30 AND
UMD.max_age >= 30 AND
UD.ethnictype = 'Caucasian (White)' AND
strpos(UMD.ethnicity,'Asian') !=0
order by user_login.last_login desc;

Next step to speed up your query is answering such question:
- How many values do I get if I ask one question.
Example:
gender='W' - 50% rows
seekgender='M' - 50% rows
ethnictype='Caucasian (White)' - 5%

Start indexing your tables on smallest values - in this situation - ethnictype. Consider using multi-column indexes.

Regards,
Tomasz Myrta


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