When you say "hanging" to you mean it's blocked and waiting, or is it
burning CPU?
Although you've used the "Outline Information into SQL Plan Profile" trick,
SQL Plan Profiles (and SQL Plan Baselines) don't always manage to reproduce
the plan (especially in the earlier releases). Do you have adaptive plans
enabled, and have you tried running the 10053 trace? It's possible given
the symptoms you've described that Oracle is spending a huge amount of time
calculating inflections points for adaptive joins.
Here's an example I wrote about a couple of years ago: Adaptive Joins |
Oracle Scratchpad (wordpress.com)
<https://jonathanlewis.wordpress.com/2022/04/13/adaptive-joins/>
Regards
Jonathan Lewis
On Fri, 15 Mar 2024 at 17:49, Laurentiu Oprea <laurentiu.oprea06@xxxxxxxxx>
wrote:
Thanks a lot Mark. Release is 12.1. Query is running on the same node
(parallel force local is true). I tried to block every decision of the
optimizer by creating a profile containing a full outline of a known good
plan. But parsing can either fail with ORA-04021 (one of the slaves raises
this error) or it completes and the query starts to run after all after
about 40 minutes.
În vin., 15 mar. 2024 la 19:05, Mark W. Farnham <mwf@xxxxxxxx> a scris:
For this one precise release and patch information will be at least
useful (if not essential).
There have been several bugs serially killed where the plans generated
for different parallel children didn’t match up. There was a failure mode
where it just kept trying to come up with a matched plan until it timed out
(which could be very long).
Running with parallel forced to a single node may avoid some of those
that were rooted in different node/instance specific plan differences.
I thought that the last vampire version of this bug had been staked in
the heart circa 2018, but I could be wrong.
mwf
*From:* oracle-l-bounce@xxxxxxxxxxxxx [mailto:
oracle-l-bounce@xxxxxxxxxxxxx] *On Behalf Of *Laurentiu Oprea
*Sent:* Friday, March 15, 2024 11:58 AM
*To:* ORACLE-L (oracle-l@xxxxxxxxxxxxx)
*Subject:* query hanged in parsing
Dear all,
Maybe you can give me an idea, I have a query running in parallel hanging
in parsing phase for very long time, I did a flamegraph and seems like
stack is looking like this (qesmaUpdatePlanSig is in top of flamegraph)
qkaComputePlanSignature
qkaTraverseQknDescendents
qknApplyCallback
qkaPlanSignatureCB
qesmaUpdatePlanSig
Any ideas what could be the reason for this??
Appreciate your help.
