non-equi self-join optimization

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От George Pavlov
Тема non-equi self-join optimization
Дата
Msg-id CCB89282FCE1024EA3DCE687A96A51640445D978@ehost010-6.exch010.intermedia.net
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Ответы Re: non-equi self-join optimization
Список pgsql-sql
I have a table of names with two subsets of entities. I want to find
those names from set 1 that are substrings of names from set 2 from the
same table. Basically the pared down query I want is something like
this:
select t1.myname, t2.myname  from mytable t1     inner join mytable t2      on position (t1.myname in t2.myname) > 0
wheret1.flag = 1    and t2.flag = 2   
;

I have gone through a few variations on the theme, but none perform too
well. Any advice on the best way to optimize a query like this would be
appreciated.

Thanks!

George


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