oracle 11g RAC 等待一例 gc current request 和 enq: US - contention

测试环境，11G R2 RAC。

有个脚本执行的时候，挂住了。检查一下：

SQL> select * from GV$SESSION_WAIT where sid = 2848 ;

INST_ID SID SEQ# EVENT P1TEXT P1 P1RAW P2TEXT
P2 P2RAW P3TEXT P3 P3RAW WAIT_CLASS_ID WAIT_CLASS# WAIT_CLASS WAIT_TIME SECONDS_IN_WAIT STATE WAIT_TIME_MICRO
TIME_REMAINING_MICRO TIME_SINCE_LAST_WAIT_MICRO

---------- ---------- ---------- ---------------------------------------------------------------- ---------------------------------------------------------------- ---------- ---------------- ---------------------------------------------------------------- ----------
---------------- ---------------------------------------------------------------- ---------- ---------------- ------------- ----------- ---------------------------------------------------------------- ---------- --------------- ------------------- ---------------
-------------------- --------------------------

1 2848 85 gc current request file# 4 0000000000000004 block#
128 0000000000000080 id# 16777253 0000000001000025 3871361733 11 Cluster 0 767 WAITING
766899151 -1 0

2 2848 17 enq: US - contention name|mode 1431502854 0000000055530006 undo segment #
17 0000000000000011 0 0 00 1893977003 0 Other 0 139240 WAITING 139240348081
-1 0

SQL>

第一个事件：

SQL> select name,parameter1,parameter2,parameter3 from v$event_name where name='gc current request';

NAME PARAMETER1 PARAMETER2 PARAMETER3

---------------------------------------------------------------- ---------------------------------------------------------------- ---------------------------------------------------------------- ----------------------------------------------------------------

gc current request file# block# id#

SQL> SELECT tablespace_name, file_name FROM dba_data_files WHERE file_id = 4;

TABLESPACE_NAME FILE_NAME

------------------------------ --------------------------------------------------------------------------------

UNDOTBS2 +XXX/xxx/undotbs02.dbf

SQL>

第二个也是说明UNDO的争用。

SQL> col file_name format a50

SQL> set lines 100

SQL> select file_name,bytes/1024/1024 from dba_data_files order by file_name;

那就扩空间吧。