RE: "direct path read" and "db file sequential read" used for full table scans in 11g

  • From: "Allen, Brandon" <Brandon.Allen@xxxxxxxxxxx>
  • To: "oracle-l@xxxxxxxxxxxxx" <oracle-l@xxxxxxxxxxxxx>
  • Date: Thu, 30 Aug 2012 21:47:29 +0000

Question #3 is open again
According to the docs the answer I thought I'd found would only explain what 
I'm seeing if I had the parameter parallel_degree_policy=AUTO, but I just 
checked and it is set to MANUAL, so the parallel queries should still be using 
direct path reads according to the doc:


NAME                                 TYPE        VALUE
------------------------------------ ----------- ------
parallel_degree_policy               string      MANUAL

From: Allen, Brandon

I found the answer to question #3 - apparently it's a new feature called 
"In-Memory Parallel Execution" as documented at the links below.  I'm still 
looking for answers on #1 and 2 though if anyone has any ideas.

From: Allen, Brandon

1)      How can I force production to use the direct path reads?

2)      Why is it using "db file sequential read" for a full table scan instead 
of "db file scattered read"?

3)      I also tried setting PARALLEL to 2 on the table in question and it did 
force Oracle to use a parallel execution plan, but it still used "db file 
sequential read" instead of "direct path read" - any idea why this could be?


Privileged/Confidential Information may be contained in this message or 
attachments hereto. Please advise immediately if you or your employer do not 
consent to Internet email for messages of this kind. Opinions, conclusions and 
other information in this message that do not relate to the official business 
of this company shall be understood as neither given nor endorsed by it.


Other related posts: