RE: Wow - has anyone used ROW_NUMBER() to get around using a UNION statement when UNION ALL doesn't work??

  • From: "Taylor, Chris David" <ChrisDavid.Taylor@xxxxxxxxxxxxxxx>
  • To: 'Wolfgang Breitling' <breitliw@xxxxxxxxxxxxx>
  • Date: Fri, 5 Aug 2011 15:15:49 -0500

Doh!  It is doing a HASH GROUP BY

(In the previous email I sent with the row source operations, it's in there...I 
looked at the first SORT UNIQUE, not the GROUP BY.

  --->21369    HASH GROUP BY (cr=318486 pr=183848 pw=45 time=23546310 us)


Chris Taylor
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Email: chris.taylor@xxxxxxxxxxxxxxx<mailto:chris.taylor@xxxxxxxxxxxxxxx>

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From: Wolfgang Breitling [mailto:breitliw@xxxxxxxxxxxxx]
Sent: Friday, August 05, 2011 2:53 PM
To: Taylor, Chris David
Cc: 'oracle-l@xxxxxxxxxxxxx'
Subject: Re: Wow - has anyone used ROW_NUMBER() to get around using a UNION 
statement when UNION ALL doesn't work??

Do you by chance have hash_group_by disabled - because of legacy code which 
expects group by to render rows in order without an explicit order by ?

In case the answer is yes, how does the union perform if you enable it for this 
session / sql ?

On 2011-08-05, at 1:30 PM, Taylor, Chris David wrote:


My bad...appears it is a SORT UNIQUE.

Some info for the UNION statement for those interested.

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