环境:
SQL> select * from v$version;

BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
PL/SQL Release 11.2.0.3.0 - Production
CORE    11.2.0.3.0      Production
TNS for Linux: Version 11.2.0.3.0 - Production
NLSRTL Version 11.2.0.3.0 - Production

问题&解决:
SQL> select  count(*) from MV_EDR_BASE_V;

在查询物化视图时,发生了os thread startup等待事件,并一直HANG住.
 
SQL> show parameter sga

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
lock_sga                             boolean     FALSE
pre_page_sga                         boolean     TRUE
sga_max_size                         big integer 40G
sga_target                           big integer 0

将pre_page_sgaFALSE
alter system set pre_page_sga=FALSE scope=spfile;
restart instant;

再次执行SQL,等待消失...