V$WAITSTAT视图

V$WAITSTAT displays block contention statistics. This table is only updated when timed statistics are enabled.ColumnDatatypeDescriptionCLASSVARCHAR2(18)Class of the blockCOUNTNUMBER        Number of waits by this OPERATION for this CLASS of blockTIMENUMBER        Sum of all wait times for all the waits by this OPERATION for this CLASS of block

[oracle@test ~]$ sqlplus / as sysdbaSQL*Plus: Release 10.2.0.5.0 - Production on Mon Jul 10 09:17:37 2017Copyright (c) 1982, 2010, Oracle.  All Rights Reserved.Connected to an idle instance.SQL> startupORACLE instance started.Total System Global Area  281018368 bytesFixed Size    2095672 bytesVariable Size  150996424 bytesDatabase Buffers  121634816 bytesRedo Buffers    6291456 bytesDatabase mounted.Database opened.SQL> desc v$waitstat ; Name   Null?    Type ----------------------------------------- -------- ---------------------------- CLASS    VARCHAR2(18) COUNT    NUMBER TIME    NUMBERSQL> set pages 300SQL> select * from v$waitstat;  CLASSCOUNT    TIME------------------ ---------- ----------data block   12      16sort block    0       0save undo block     0       0segment header    0       0save undo header    0       0free list    0       0extent map    0       01st level bmb    0       02nd level bmb    0       03rd level bmb    0       0bitmap block    0       0bitmap index block    0       0file header block    2       1unused    0       0system undo header    0       0system undo block    0       0undo header    0       0undo block    0       018 rows selected.SQL> select * from v$waitstat order by class;CLASSCOUNT    TIME------------------ ---------- ----------1st level bmb    0       02nd level bmb    0       03rd level bmb    0       0bitmap block    0       0bitmap index block    0       0data block   12      16extent map    0       0file header block    2       1free list    0       0save undo block     0       0save undo header    0       0segment header    0       0sort block    0       0system undo block    0       0system undo header    0       0undo block    0       0undo header    0       0unused    0       018 rows selected.SQL>