Expert Oracle Exadata - Parent Directory

CHAPTER 10 EXADATA WAIT EVENTSWAIT #1: nam='kfk: async disk IO' ela= 24 count=1 intr=0 timeout=4294967295 obj#=66856WAIT #1: nam='kfk: async disk IO' ela= 8 count=1 intr=0 timeout=4294967295 obj#=66856WAIT #1: nam='direct path read' ela= 1410 file number=6 first dba=1304064 block cnt=128obj#=66856WAIT #1: nam='kfk: async disk IO' ela= 24 count=1 intr=0 timeout=4294967295 obj#=66856WAIT #1: nam='kfk: async disk IO' ela= 21 count=1 intr=0 timeout=4294967295 obj#=66856WAIT #1: nam='kfk: async disk IO' ela= 24 count=1 intr=0 timeout=4294967295 obj#=66856WAIT #1: nam='kfk: async disk IO' ela= 23 count=1 intr=0 timeout=4294967295 obj#=66856WAIT #1: nam='kfk: async disk IO' ela= 23 count=1 intr=0 timeout=4294967295 obj#=66856WAIT #1: nam='kfk: async disk IO' ela= 23 count=1 intr=0 timeout=4294967295 obj#=66856WAIT #1: nam='kfk: async disk IO' ela= 32 count=1 intr=0 timeout=4294967295 obj#=66856WAIT #1: nam='kfk: async disk IO' ela= 28 count=1 intr=0 timeout=4294967295 obj#=66856WAIT #1: nam='kfk: async disk IO' ela= 21 count=1 intr=0 timeout=4294967295 obj#=66856WAIT #1: nam='kfk: async disk IO' ela= 25 count=1 intr=0 timeout=4294967295 obj#=66856WAIT #1: nam='kfk: async disk IO' ela= 31 count=1 intr=0 timeout=4294967295 obj#=66856WAIT #1: nam='kfk: async disk IO' ela= 7 count=1 intr=0 timeout=4294967295 obj#=66856WAIT #1: nam='direct path read' ela= 16725 file number=6 first dba=1303171 block cnt=125obj#=66856WAIT #1: nam='kfk: async disk IO' ela= 24 count=1 intr=0 timeout=4294967295 obj#=66856WAIT #1: nam='kfk: async disk IO' ela= 27 count=1 intr=0 timeout=4294967295 obj#=66856WAIT #1: nam='kfk: async disk IO' ela= 8 count=1 intr=0 timeout=4294967295 obj#=66856Again we see the repeating pattern of a single direct path read event followed by several kfk:async disk IO events. The cell smart index scan event replaces both of these events. The enq: KO –fast object checkpoint events for flushing dirty blocks prior to starting the direct path reads are stillpresent (although not shown in this excerpt because they occur in the query coordinator process, not inthe parallel slave processes).ParametersJust as with the cell smart table scan event, the parameters for cell smart index scan do not containa lot of details. The cell hash number and the object ID of the segment being scanned are the onlyinformation provided.P1 - Cell hash numberP2 - Not usedP3 - Not usedobj# - The object number of the index being scannedcell single block physical readThis event is equivalent to the db file sequential read event used on non-Exadata platforms. Singleblock reads are used most often for index access paths (both the index block reads and the table blockreads via rowids from the index lookups). They can also be used for a wide variety of other operationswhere it makes sense to read a single block.328