How about
with par_ as (select * from product_parent where parent_name like 'aa%' )
select distinct product_code from product p_
inner join par_ on p_.parent_id=par_.id
limit 2
?
2012/4/3 Istvan Endredy
<istvan.endredy@gmail.com> Hi,
i've ran into a planning problem.
select distinct product_code from product p_
inner join product_parent par_ on p_.parent_id=par_.id
where par_.parent_name like 'aa%' limit 2
If effective_cache_size is smaller (32MB), planning is ok and query is fast. (10ms)
In the worst case (effective_cache_size=6GB) the speed depends on the value of 'limit' (in select): if it is smaller, query is slower. (12ms)
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Best regards,
Vitalii Tymchyshyn