Expert Oracle Exadata - Parent Directory

CHAPTER 10 EXADATA WAIT EVENTSWAIT #478: nam='reliable message' ela= 2005 channel context=118 channel handle=120 ...obj#=523WAIT #478: nam='enq: KO - fast object checkpoint' ela= 156 ... obj#=523 ...WAIT #478: nam='PX Deq: Join ACK' ela= 772 sleeptime/senderid=268 passes=1 p3=120 obj#=523 ...WAIT #478: nam='PX Deq: Join ACK' ela= 932 sleeptime/senderid=268 passes=8 p3=120 obj#=523 ...WAIT #478: nam='PX Deq: Join ACK' ela= 2 sleeptime/senderid=0 passes=0 p3=0 obj#=523 ...ParametersHere are the parameters for the resmgr:pq queued event.P1 - LocationP2 - Not usedP3 - Not usedobj# - NAThe location parameter is a numeric value that most likely refers to a location (function) in the Oraclecode as described above in the resmgr:cpu quantum event.SummaryThe wait interface has been expanded to cover several Exadata-specific features. In this chapter we’vecovered the new wait events. By far the most interesting of the new events are cell smart table scanand cell smart index scan. These events cover the time spent waiting on an offloadable I/O request toa storage cell. There is a lot of processing that occurs at the storage layer that is lumped together underthese events. It’s important to understand that these events replace the direct path read event and thatthe mechanism of returning the data directly to the process PGA employed by the Smart Scan events isanalogous to the way it is handled by direct path read.343