遇到direct path sync等待事件
在使用hvr測試 大表同步的時候，遇到direct path sync等待事件，經過查詢官方文檔，http://docs.oracle.com/cd/E11882_01/server.112/e40402/waitevents003.htm#REFRN00538
有說明如下：
direct path sync
During Direct Path write operations the data is asynchronously written to the database files. At some point the session needs to ensure that all outstanding asynchronous I/O have been completed to disk. On Unix the fsync command, which synchronizes data to disk, is issued to confirm that all the writes have completed and the data is all on disk.
Wait Time: The time taken for the fsync operation to complete, which normally is the time taken to complete the outstanding I/Os.
看上面的說明，是在等待“fsync操作寫完畢”的等待時間。
額外說一句：
該等待事件是從10.2.0.5開始有的，如下是測試：
Microsoft Windows [版本 6.1.7600] 版權所有 (c) 2009 Microsoft Corporation。保留所有權利。 C:\Users\Administrator>f: F:\>cd oracle\product\10.2.0\db_1\BIN F:\oracle\product\10.2.0\db_1\BIN>set oracle_sid=fs F:\oracle\product\10.2.0\db_1\BIN>net start oracleservicefs OracleServiceFS 服務正在啟動 .................. OracleServiceFS 服務已經啟動成功。 F:\oracle\product\10.2.0\db_1\BIN>sqlplus / as sysdba SQL*Plus: Release 10.2.0.4.0 - Production on Sat May 30 21:30:02 2015 ------>10.2.0.4 Copyright (c) 1982, 2007, Oracle. All Rights Reserved. Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options 21:30:58 sys@FS> col name format a30 21:31:05 sys@FS> col wait_class format a30 21:31:20 sys@FS> select name,wait_class from v$event_name where name like '%direct path%'; NAME WAIT_CLASS ------------------------------ ------------------------------ direct path read User I/O direct path read temp User I/O direct path write User I/O direct path write temp User I/O Elapsed: 00:00:00.00 21:31:21 sys@FS>
[oracle@lei1 ~]$ sqlplus / as sysdba SQL*Plus: Release 10.2.0.5.0 - Production on Sun May 31 05:37:11 2015 Copyright (c) 1982, 2010, Oracle. All Rights Reserved. Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production ---------->10.2.0.5 With the Partitioning, OLAP, Data Mining and Real Application Testing options SQL> set line 200 SQL> col name format a30 SQL> col wait_class format a30 SQL> select name,wait_class from v$event_name where name like '%direct path%'; NAME WAIT_CLASS ------------------------------ ------------------------------ direct path sync User I/O ------------------->有此等待事件 direct path read User I/O direct path read temp User I/O direct path write User I/O direct path write temp User I/O SQL>
