问Oracle查询执行第一次完成，但在第二次运行时挂起。

EN

$ sqlplus sys/system as sysdba;
SQL> SELECT * FROM v$version;

BANNER
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Oracle Database 11g 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

SQL> alter session set current_schema = DB_2017_2018;

SQL> alter session set NLS_DATE_FORMAT = 'YYYY-MM-DD';

SQL> select 1 from complex_view where company_id = 1 and invoice_month = 1 and invoice_year = 2018;
-- runs in 33 sec

SQL> select 1 from complex_view where company_id = 1 and invoice_month = 1 and invoice_year = 2018;
-- hangs up.. Ctrl + C after 3 minutes

SQL> select * from complex_view where company_id = 1 and invoice_month = 1 and invoice_year = 2018;
-- runs in 1m 30 sec

SQL> select * from complex_view where company_id = 1 and invoice_month = 1 and invoice_year = 2018;
-- hangs up.. Ctrl + C after 5 - 10 minutes

-- ALL THESE COMMANDS / QUERIES RUN IN SAME SESSION

SQL> alter system flush shared_pool;
SQL> alter system flush buffer_cache;

SQL> ALTER SYSTEM KILL SESSION '12,256' IMMEDIATE;