_gby_hash_aggregation_enabled=false
- From: "Allen, Brandon" <Brandon.Allen@xxxxxxxxxxx>
- To: <oracle-l@xxxxxxxxxxxxx>
- Date: Thu, 29 Nov 2007 15:10:03 -0700
Has anyone else tried setting this hidden parameter and found it didn't
disable the HASH GROUP BY feature? It's suggested in Metalink 387958.1
as a workaround to the "wrong results" bug (4604970) with the new HASH
GROUP BY feature, so I just set it as follows:
SQL> alter system set "_gby_hash_aggregation_enabled"=false;
System altered.
Then I ran a 10046 trace on a query known to have the HASH GROUP BY
operation in its explain plan:
SQL> alter session set sql_trace=true;
Session altered.
SQL> @dts1
. . .
2310 rows selected.
But, in the trace file, it still shows that HASH GROUP BY is being used:
STAT #1 id=2 cnt=952 pid=1 pos=1 obj=0 op='HASH GROUP BY (cr=2395 pr=0
pw=0 time=49601 us)'
Next, I tried setting optimizer_features_enable="10.1.0" as recommended
in the same Metalink article and that worked as expected - the trace
file showed SORT GROUP BY instead of the HASH GROUP BY.
I've already got an SR open, so we'll see what they say but I'm curious
if others have encountered the same thing. I don't want to set
optimizer_features_enable to 10.1.0 at the system level so if the hidden
parameter doesn't really work, then I'll have to install patchset
10.2.0.3 instead.
Thanks,
Brandon
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:
