Expert Oracle Exadata - Parent Directory

CHAPTER 3 HYBRID COLUMNAR COMPRESSIONenq: US - contention 439 3.98 82.64Disk file operations I/O 110 0.00 0.02control file sequential read 720 0.17 1.64cell single block physical read 131 0.05 0.26db file single write 72 0.06 0.23KSV master wait 431 2.10 5.24ASM file metadata operation 144 0.00 0.01kfk: async disk IO 36 0.09 0.35cell smart file creation 4779 0.08 1.05CSS operation: action 1 0.00 0.00enq: CF - contention 36 0.19 0.24control file parallel write 108 0.09 0.95DFS lock handle 252 0.38 3.06undo segment extension 163 1.02 9.95L1 validation 2 0.01 0.01reliable message 50 0.00 0.05latch: row cache objects 1 0.00 0.00gc cr grant 2-way 1 0.00 0.00gc cr multi block request 4 0.00 0.00log file switch (checkpoint incomplete) 6 3.29 4.15latch: undo global data 3 0.00 0.00latch free 7 0.05 0.07latch: gc element 4 0.00 0.00wait list latch free 2 0.00 0.00log file sync 1 0.00 0.00latch: object queue header operation 3 0.00 0.00Stat NameEvents/Sec--------------------------------------- ----------HSC OLTP Space Saving 30,485HSC OLTP Compressed Blocks 10HSC Compressed Segment Block Changes 8,314STAT, HSC Heap Segment Block Changes 8,314STAT, HSC OLTP Non Compressible Blocks 10STAT, HSC OLTP positive compression 20HSC OLTP inline compression 20The second example demonstrates that a row is migrated from an HCC block when it is updated.Basically we’ll update a single row, see that its rowid has changed, verify that we can still get to therecord via its original rowid, and check to see if the TABLE FETCH CONTINUED ROW statistic gets updatedwhen we access the row via its original rowid.SYS@SANDBOX1> @table_size2Enter value for owner: KSOEnter value for table_name: SKEW_HCC3OWNER SEGMENT_NAME TOTALSIZE_MEGS COMPRESS_FOR-------------------- ------------------------------ -------------- ------------KSO SKEW_HCC3 18.6 ARCHIVE LOW--------------sum 18.686