几个视图的功能，来自官方文档

v$sqltextV$SQLTEXT displays the text of SQL statements belonging to shared SQL cursors in the SGA.V$SESSIONV$SESSION displays session information for each current session.v$wait_chains

V$WAIT_CHAINS displays information about blocked sessions. A wait chain is comprised of sessions that are blocked by one another. Each row represents a blocked and blocker session pair. If a wait chain is not a cyclical wait chain, then the last row for the chain does not have a blocker. 找到造成等待的SQL

1. select * from v$sqltext 
2.     where 
3.         (hash_value,address) in 
4.     ( 
5.         SELECT DECODE(sql_hash_value, 0, prev_hash_value, sql_hash_value), 
6.             DECODE(sql_hash_value, 0, prev_sql_addr,sql_address) 
7.         FROM v$session 
8.             where sid in (select sid from v$wait_chains) 
9. );