作为DBA需要对oracle的连接情况和内存使用情况了如指掌，不能等出问题的时候再去排除问题，平时也需要做好监控。下面分享下怎么通过sql去查看oracle的连接情况和内存使用情况。

1、查看连接oracle的所有机器的连接数

select machine,count(*) from v$session group by machine;

2、查看连接oracle的所有机器的连接数和状态

select machine,status,count(*)from v$sessiongroup by machine,statusorder by status;

3、oracle的PGA、SGA和process count

select 'SGA' AS NAME,ROUND(sum(value)/1024/1024,2)||'M' AS "SIZE(M)" from v$sga;

select 'PGA' AS NAME,ROUND(value/1024/1024,2)||'M' AS "SIZE(M)" from v$pgastatwhere name='total PGA allocated';

select 'TOTAL' AS NAME,((SELECT ROUND(sum(value)/1024/1024,2)from v$sga)+(select ROUND(value/1024/1024,2)from v$pgastatwhere name='total PGA allocated'))||'M' AS "SIZE(M)" FROM DUAL;

SELECT NAME,TO_CHAR(VALUE)FROM V$PGASTATWHERE NAME='process count';

4、查看oracle进程消耗的内存

SELECT * FROM V$PROCESS_MEMORY;

5、查看oracle进程的使用

SELECT PROGRAM, PGA_USED_MEM, PGA_ALLOC_MEM, PGA_FREEABLE_MEM, PGA_MAX_MEM FROM V$PROCESS;

大家有什么好的sql也可以一起分享下哦，共勉。

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