Expert Oracle Exadata - Parent Directory

CHAPTER 10 EXADATA WAIT EVENTSLOAD AS SELECT 3LOAD TABLE CONVENTIONAL 1UPDATE 1You’ll notice that on this particular system, the cell smart file creation event was occasionallygenerated by a DELETE statement. The fact that a DELETE could cause this event might be a littlesurprising. But remember that this event is actually timing a section of code that does block formatting,not file creation.ParametersThe only parameter of interest for this event is P1, which shows which cell was being accessed when thisevent was generated.P1 - Cell hash numberP2 - Not usedP3 - Not usedcell statistics gatherThe cell statistics gather event records time spent reading from various V$ and X$ tables. Althoughthe event is grouped in the User I/O category, it does not refer to I/O in the sense of reading and writingto and from disk.Event MeaningTime is clocked to this event when a session is reading from V$CELL, V$CELL_THREAD_HISTORY(X$KCFISOSSN), V$CELL_REQUEST_TOTALS (X$KCFISOSST), and a few other X$ tables in the same family. Theevent is miscategorized in our opinion and does not really belong in the User I/O category.ParametersThe parameters for this event provide no additional information. In fact, values are not even set for theparameters in this event. Here are the parameter definitions:P1 - Cell hash number (always 0)P2 - Not usedP3 - Not usedExadata Wait Events in the System I/O ClassThe Exadata wait events that are assigned to the System I/O class are of less importance and do notgenerally show up as major consumers of time. The backup events are the most interesting as theyrecord time for sections of code that have been optimized on the Exadata platform. The others are333