From: | hamann(dot)w(at)t-online(dot)de |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: question about alternate ordering of results |
Date: | 2012-04-10 16:50:54 |
Message-ID: | wolfgang-1120410185054.A0115484@amadeus3.local |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-general |
Hi Tom,
declaring another operator class helped. At first, however,
results were sorted deifferent than expected. A little gdb session revealed that
if fact only the FUNCTION 1 entry in the operator class is used
Regards
Wolfgang Hamann
>>
>> hamann(dot)w(at)t-online(dot)de writes:
>> > Now, in versions 8 and later the "using <&-" is rejected,
>> > the ordering op "needs to be < or > member of a btree operator class".
>> > What is needed to create the old behaviour again
>> > - create a complete operator class, including new names for the unchanged equals/not equals function?
>>
>> Yes. It sounds like you have pretty much all the spare parts you need,
>> you just have to collect them together into an opclass for each
>> ordering you want.
>>
>> > Is this relevant to performance?
>>
>> Somewhat, in that it helps the planner optimize ordering considerations.
>> But IIRC the main argument for tightening it up was to catch mistakes
>> wherein somebody says "ORDER BY x USING &&", or some other operator that
>> doesn't produce a consistent sort order.
>>
>> regards, tom lane
From | Date | Subject | |
---|---|---|---|
Next Message | Joshua D. Drake | 2012-04-10 17:55:13 | PgNext CFP still open |
Previous Message | Fujii Masao | 2012-04-10 15:07:41 | Re: [streaming replication] 9.1.3 streaming replication bug ? |