Re: BUG #5755: Query Optimzer Bug

On 17.11.2010 18:05, Tom Lane wrote:
> "Elliott Groszek"<elliott.groszek@navy.mil>  writes:
>> The following SQL statements produce different query plans even though
>> "phone" is not reference in the SQL!
>
>> explain update customer set login_name =
>> (select "NESSOuserName" from person,phone
>> where person.cac_cert=customer.cac_cert);
>
>> explain update customer set login_name =
>> (select "NESSOuserName" from person
>> where person.cac_cert=customer.cac_cert);
>
> That's not a bug.

Particularly, note that they produce different results if "phone" table
is empty.

--
   Heikki Linnakangas
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