檢視會話記憶體占用情況
select server "連線型別",
s.username,
osuser,
name,
value/1024/1024 "占用記憶體mb",
s.sid "會話id",
s.serial#,
spid "作業系統程序id",
p.pga_used_mem,
p.pga_alloc_mem,
p.pga_freeable_mem,
p.pga_max_mem
from v$session s, v$sesstat st, v$statname sn, v$process p
where st.sid = s.sid
and st.statistic# = sn.statistic#
and sn.name like 'session pga memory'
and p.addr = s.paddr
order by value desc
如果想殺死指定會話alter system kill session 'sid,serial#';,記憶體沒有釋放執行如下步驟；
select a.spid,b.sid,b.serial#,b.username from v$process a,v$session b where a.addr=b.paddr and b.status='killed' ;
檢視killed狀態的會話，
windows下：orakill.exe orcl spid，其中orcl是資料庫的sid，spid是上面查詢出來的
linux下：kill -9 spid；
sql消耗資源情況查詢：
從v$sqlarea中查詢最占用資源的查詢
select b.username username,a.disk_reads reads,
a.executions exec,a.disk_reads/decode(a.executions,0,1,a.executions) rds_exec_ratio,
a.sql_text statement
from v$sqlarea a,dba_users b
where a.parsing_user_id=b.user_id
and a.disk_reads > 100000
order by a.disk_reads desc;
用buffer_gets列來替換disk_reads列可以得到占用最多記憶體的sql語句的相關資訊。
v$sql是記憶體共享sql區域中已經解析的sql語句。
列出使用頻率最高的5個查詢
select sql_text,executions
from (select sql_text,executions,
rank() over
(order by executions desc) exec_rank
from v$sql)
where exec_rank <=5;
消耗磁碟讀取最多的sql top5
select disk_reads,sql_text
from (select sql_text,disk_reads,
dense_rank() over
(order by disk_reads desc) disk_reads_rank
from v$sql)
where disk_reads_rank <=5;
找出需要大量緩衝讀取（邏輯讀）操作的查詢
select buffer_gets,sql_text
from (select sql_text,buffer_gets,
dense_rank() over
(order by buffer_gets desc) buffer_gets_rank
from v$sql)
where buffer_gets_rank<=5;
時間占用多的：
select s.sql_text,
s.sql_fulltext,
s.sql_id,
round(elapsed_time / 1000000 / (case
when (executions = 0 or nvl(executions, 1) = 1) then
1else
executions
end),
2) "執行時間's'",
s.executions "執行次數",
s.optimizer_cost "cost",
s.sorts,
s.module, --連線模式（jdbc thin client：程式）
-- s.locked_total,
--s.physical_read_bytes "物理讀",
-- s.physical_read_requests "物理讀請求",
--s.physical_write_requests "物理寫",
-- s.physical_write_bytes "物理寫請求",
s.rows_processed "返回行數",
s.disk_reads "磁碟讀",
s.direct_writes "直接路徑寫",
s.parsing_schema_name,
s.last_active_time
from **$sqlarea s
where round(elapsed_time / 1000000 / (case
when (executions = 0 or nvl(executions, 1) = 1) then
1else
executions
end),
2) > 5 --100 0000微秒=1s
and s.parsing_schema_name = user
and to_char(s.last_load_time, 'yyyy-mm-dd') =
to_char(sysdate, 'yyyy-mm-dd')
and s.command_type in (2, 3, 5, 6, 189)
order by "執行時間's'" desc;
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