Enable Parallel DML or Not?
- From: Kellyn Pedersen <kjped1313@xxxxxxxxx>
- To: oracle Freelists <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 7 Oct 2009 08:20:13 -0700 (PDT)
I have to say as much as I learn about parallel processing everyday, the more
questions I have...:)
I have numerous CTAS operations that load tables with large parallel degrees in
both the insert as well as the select, (see example below...)
create table member_0_ordersum2 compress pctfree 0 tablespace MARTLARGE
parallel(degree 16) as
SELECT/*+ parallel (i 16) parallel (s 16)*/ o1.ibid
,recency_key
, ROUND(NVL(AVG(o1.nrt_gap_days), 0), 0) AS adbo
, ROUND(NVL(AVG(o1.onl_gap_days), 0), 0) AS adbo_o...
When I view these through OEM, it is not receiving the parallel on the table
creation(insert) and is, of course, using a huge amount of temp space for the
hash/sort processes, so I'm seeing large waits on direct read and writes to my
temp tablespace group, along with sequential reads on the partitions in
question, (but I find this to be an actual index from the data dictionary
causing it to be a sequential read wait, not the actual partition, BTW.)
I've read misleading information view the web on CTAS being a parallel_DML
statement, which I didn't think it was and if it is, would require me to enable
parallel DML before the create table statement.
QUESTION- Is this just a mistake by some educated folks out there or are CTAS
considered a parallel DML statement along with merge, insert, update and delete
when using parallel?
Thanks!
Kellyn Pedersen
Multi-Platform DBA
I-Behavior
Other related posts:
