X $ BH.CLASS Classification, in turn, record SQL> Select * from V $ Version; banner -------------------------------------------------------------------------------------------- ----------------------------------------- Oracle9i Enterprise Edition Release 9.2.0.1.0 - ProductionPL / SQL Release 9.2.0.1.0 - ProductionCORE 9.2.0.1.0 ProductionTNS for 32-bit Windows: Version 9.2.0.1.0 - ProductionNLSRTL Version 9.2.0.1.0 - ProductionSQL> SQL> select * from v $ waitstat; Class Count Time -------------------------- ---------- Data Block 2 1Sort Block 0 0save undo block 0Segment Header 1 0save undo header 0 0 01st Level BMB 0 02nd Level BMB 0 03rd Level BMB 0 0Bitmap Block 0 0class Count Time ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ---------- --------- Bitmap Index Block 0 0 0x iystem undo header 0 0System undo block 0 0Undo Header 0 0undo Block 0 0 Selected 18 rows. SQL> SQL> SELECT DISTINCT CLASW $ BH ORDER BY CLAS; Class ---------- 148912131517 From here to undo header / undo block 181920Class ---------- 21293031Class- --------- 3233343536 27 lines have been selected. SQL> Oracle 7 Non-system returning segment starts from 9, 8i starts from 13, basically understand, V $ WaitStat is a waiting for all types of blocks in Data Buffer
