Hi All,
We are using Oracle 11g RAC
One of our datawarehouse report queries took 1000 seconds to run during our performance tests. This surprised all below is the event that we got . Suprisigly there was no data for query to return still it took 1000 seconds usually it comes out withing 60 seconds .
Going through AWR we saw below event. Very little information on net regrading what this event is
Most site just say " It is related to Parallel queries "
In my earlier article i had faced issue of where Query coordinator was not able to receive data, so i suspected that to be the issue here
We are using Oracle 11g RAC
One of our datawarehouse report queries took 1000 seconds to run during our performance tests. This surprised all below is the event that we got . Suprisigly there was no data for query to return still it took 1000 seconds usually it comes out withing 60 seconds .
Going through AWR we saw below event. Very little information on net regrading what this event is
Most site just say " It is related to Parallel queries "
In my earlier article i had faced issue of where Query coordinator was not able to receive data, so i suspected that to be the issue here
PX Deq Credit: send blkd---- Query coordinator
receives data from lot of parallel processes and must process that information.
Suppose a process P3 has send information to query coordinator , before query
coordiantor accepts new information from this process it must finish processing
the earlier request. So now P3 is
blocked until QC finishes processing the data it last sent
Bottom line -- If you see this event check your Foreground and Background events for events related to parallel query processing.
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