Oracle查询连接数和sql快慢脚本
一、查询执行最慢的sql

select *
  from (select sa.SQL_TEXT,
               sa.SQL_FULLTEXT,
               sa.EXECUTIONS "执行次数",
               round(sa.ELAPSED_TIME / 1000000, 2) "总执行时间",
               round(sa.ELAPSED_TIME / 1000000 / sa.EXECUTIONS, 2) "平均执行时间",
               sa.COMMAND_TYPE,
               sa.PARSING_USER_ID "用户ID",
               u.username "用户名",
               sa.HASH_VALUE
          from v$sqlarea sa
          left join all_users u
            on sa.PARSING_USER_ID = u.user_id
         where sa.EXECUTIONS > 0
         order by (sa.ELAPSED_TIME / sa.EXECUTIONS) desc)
 where rownum <= 50;

二、查询次数最多的 sql

select *
  from (select s.SQL_TEXT,
               s.EXECUTIONS "执行次数",
               s.PARSING_USER_ID "用户名",
               rank() over(order by EXECUTIONS desc) EXEC_RANK
          from v$sql s
          left join all_users u
            on u.USER_ID = s.PARSING_USER_ID) t
 where exec_rank <= 100;

三、oracle 查看最大连接数

select value from v$parameter where name = 'processes' --数据库允许的最大连接数

四、oracle 查看当前连接数

select count(*) from v$process --当前的连接数