On 2008-08-28, at 21:31, Emi Lu wrote:
Good morning,
Tried to compare Table1 based on Table2
. update table1.col = false
if table1.pk_cols not in table2.pk_cols
For the following two ways, (2) always performs better than (1) right,
and I need your inputs.
======================================================================
==
(1) update table1
set col = false
where table1.pk_co1 || table1.pk_col2.... || table1.pk_colN
NOT IN
(select pk_co1 || pk_col2.... || pk_colN
from table2
)
(2) ResultSet(rs) =
select pk_col1||pk_col2... || pk_colN
from table1
left join table2 using (pk_col1..., pk_colN)
where table2.pk_col1 is null
Then for each rs record, do:
update table1
set col = false
where col1||... colN in rs.value
Thanks a lot!
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Pawel Socha
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