增強plsql developer的session工具
一, 過濾器
Pl/sql developer工具默認爲session工具提供三種過濾器: all sessions. User session, active sessions. 這裏, 作者將新增一種過濾器: 所有正在等待的鏈接.
1.1 all session.
select
b.SADDR,b.SID,b.SERIAL#,b.AUDSID,b.PADDR,b.USER#,b.USERNAME,b.COMMAND,b.OWNERID,b.TADDR,
b.LOCKWAIT,b.STATUS,b.SERVER,b.SCHEMA#,b.SCHEMANAME,b.OSUSER,b.PROCESS,b.MACHINE,b.TERMINAL,b.PROGRAM,
b.TYPE,b.SQL_ADDRESS,b.SQL_HASH_VALUE,b.PREV_SQL_ADDR,b.PREV_HASH_VALUE,b.MODULE,b.MODULE_HASH,b.ACTION,
b.CLIENT_INFO,b.FIXED_TABLE_SEQUENCE,b.ROW_WAIT_OBJ#,b.ROW_WAIT_FILE#,b.ROW_WAIT_BLOCK#,b.ROW_WAIT_ROW#,
b.LOGON_TIME ,a.EVENT,a.P1TEXT,a.P1,a.P1RAW,a.p2text,a.p2,a.p2raw,a.p3text,
a.p3, a.p3raw,a.wait_time,a.seconds_in_wait,a.state
from v$session_wait a,v$session b
where a.sid = b.sid
and b.username is not null
order by logon_time desc, sid
這裏給出了所有的session, 包括oracle後臺session和用戶session. 並額外給出了所有session的當前等待事件. 包括正在空閒等待用戶輸入的session.
注意, 給定的sql語句後面不能加分號.
1.2 user sessions
這裏使用到了pl sql 的全局變量user, 這個值爲當前使用pl/sql developer登錄到oracle服務器的用戶名.
select
b.SADDR,b.SID,b.SERIAL#,b.AUDSID,b.PADDR,b.USER#,b.USERNAME,b.COMMAND,b.OWNERID,b.TADDR,
b.LOCKWAIT,b.STATUS,b.SERVER,b.SCHEMA#,b.SCHEMANAME,b.OSUSER,b.PROCESS,b.MACHINE,b.TERMINAL,b.PROGRAM,
b.TYPE,b.SQL_ADDRESS,b.SQL_HASH_VALUE,b.PREV_SQL_ADDR,b.PREV_HASH_VALUE,b.MODULE,b.MODULE_HASH,b.ACTION,
b.CLIENT_INFO,b.FIXED_TABLE_SEQUENCE,b.ROW_WAIT_OBJ#,b.ROW_WAIT_FILE#,b.ROW_WAIT_BLOCK#,b.ROW_WAIT_ROW#,
b.LOGON_TIME ,a.EVENT,a.P1TEXT,a.P1,a.P1RAW,a.p2text,a.p2,a.p2raw,a.p3text,
a.p3, a.p3raw,a.wait_time,a.seconds_in_wait,a.state
from v$session_wait a,v$session b
where a.sid = b.sid
and b.username = user
order by logon_time desc, sid
1.3 active sessions
使用過濾條件status=’ACTIVE’得到所有活動的session.
select
b.SADDR,b.SID,b.SERIAL#,b.AUDSID,b.PADDR,b.USER#,b.USERNAME,b.COMMAND,b.OWNERID,b.TADDR,
b.LOCKWAIT,b.STATUS,b.SERVER,b.SCHEMA#,b.SCHEMANAME,b.OSUSER,b.PROCESS,b.MACHINE,b.TERMINAL,b.PROGRAM,
b.TYPE,b.SQL_ADDRESS,b.SQL_HASH_VALUE,b.PREV_SQL_ADDR,b.PREV_HASH_VALUE,b.MODULE,b.MODULE_HASH,b.ACTION,
b.CLIENT_INFO,b.FIXED_TABLE_SEQUENCE,b.ROW_WAIT_OBJ#,b.ROW_WAIT_FILE#,b.ROW_WAIT_BLOCK#,b.ROW_WAIT_ROW#,
b.LOGON_TIME ,a.EVENT,a.P1TEXT,a.P1,a.P1RAW,a.p2text,a.p2,a.p2raw,a.p3text,
a.p3, a.p3raw,a.wait_time,a.seconds_in_wait,a.state
from v$session_wait a,v$session b
where a.sid = b.sid
and b.username is not null
and b.status = 'ACTIVE'
order by logon_time desc, sid
1.4 所有session 的當前等待
動態性能視圖v$session_waits中存儲了所有用戶的當前等待, 這裏我們只關注跟IO和buffer space, latch 相關的幾個常見的等待事件.
select a.EVENT,a.P1TEXT,a.P1,a.P1RAW,a.p2text,a.p2,a.p2raw,a.p3text,
a.p3, a.p3raw,a.wait_time,a.seconds_in_wait,a.state,
b.SADDR,b.SID,b.SERIAL#,b.AUDSID,b.PADDR,b.USER#,b.USERNAME,b.COMMAND,b.OWNERID,b.TADDR,
b.LOCKWAIT,b.STATUS,b.SERVER,b.SCHEMA#,b.SCHEMANAME,b.OSUSER,b.PROCESS,b.MACHINE,b.TERMINAL,b.PROGRAM,
b.TYPE,b.SQL_ADDRESS,b.SQL_HASH_VALUE,b.PREV_SQL_ADDR,b.PREV_HASH_VALUE,b.MODULE,b.MODULE_HASH,b.ACTION,
b.CLIENT_INFO,b.FIXED_TABLE_SEQUENCE,b.ROW_WAIT_OBJ#,b.ROW_WAIT_FILE#,b.ROW_WAIT_BLOCK#,b.ROW_WAIT_ROW#,
b.LOGON_TIME
from v$session_wait a,v$session b
where a.sid = b.sid
and b.username is not null
and b.type <> 'BACKGROUND'
and a.event in ('db file sequential read', 'db file scattered read',
'latch free', 'direct path read', 'direct path write',
'enqueue', 'library cache pin', 'library cache load lock',
'buffer busy waits', 'free buffer waits')
二, 詳細資料
過濾器給出的是對連接session的篩選過程. 詳細資料部分給出了指定(在過濾文本中選中)的session的詳細信息. 比如指定session的執行過程cursor及其全部sql語句. 比如session當前正在執行(active session)或者最後一次執行的sql語句(inactive session)
2.1 遊標
V$open_cursor中存儲有給定session的所有子游標及其執行過程. 但v$open_cursor視圖中給定的sql_text不完整. 所以如果需要查看完整的執行語句, 我們需要跟v$sql_text進行關聯.
select a.TYPE,b.ADDRESS,b.HASH_VALUE,c.PIECE,c.SQL_TEXT
from v$session a, v$open_cursor b, v$sqltext c
where a.sid = b.sid
and b.ADDRESS = c.ADDRESS
and b.HASH_VALUE = c.HASH_VALUE
and a.SID = :sid
order by b.ADDRESS,b.HASH_VALUE,c.PIECE
/*concatenate*/
2.2 sql文本
這裏給出的是session正在執行的sql語句(對於inactive session來說是最後一次執行的sql文本). 對應於 active session, 我們可以使用sql_hash_value和sql_address關聯v$sql_text得到我們需要的結果, 但inactive session的sql_hash_value爲0, 這時就需要使用prev_sql_addr和prev_hash_value得到我們希望的值.
select sql_text from v$sqltext_with_newlines
where address = hextoraw(decode(:sql_hash_value,0,:PREV_SQL_ADDR,:sql_address))
and hash_value = decode(:sql_hash_value,0,:prev_hash_value,:sql_hash_value)
order by piece
/* concatenate */
2.3 統計表
統計表是從v$sess_events視圖中查詢得到的session的資源利用情況. 由於一些等待事件只有在session完成後纔會更新其彙總數據, 所以這裏得到的結果可能會跟實際情況有些偏差, 明細的結果參照logoff trigger跟蹤得到的結果信息.
select names.name, stats.statistic#, stats.value
from v$sesstat stats, v$statname names
where stats.sid = :sid
and names.Statistic# = stats.Statistic#
and stats.VALUE > 0
order by stats.VALUE desc,stats.statistic#
2.4 鎖.
默認的查詢語句效率不是一般的差. 稍作修改如下.
select /*+ ordered use_hash(o b)*/
b.*,
o.owner object_owner,
o.object_name
from v$lock b, dba_objects o
where b.sid = :sid
and o.object_id = b.ID1
and b.id1 = :p2
and b.id2 = :p3
and b.BLOCK = 1
2.5 解析等待事件明細
我們要定位到當前等待事件正在跟蹤的數據庫對象的話需要查詢dba_extents動態性能視圖.但Dba_extents視圖的查詢效果非常差. 使用這個視圖定位對象的時間花銷較大. 我們有兩種方式解決這個問題.
首先, 我們可以使用v$bh代替dba_extents執行查詢. V$bh中存儲當前data buffer中的所有數據對象. 但這個查詢方式存在的問題在於, 我們需要等待查詢的對象進入緩衝區之後才能得到查詢結果, 而對於那些db file sequential read和db file scattered read查詢來說, 有可能在我們執行查詢時對應仍然未在緩衝區中.
另外, 我們可以通過建立dba_extents的映像表來加速這個查詢過程, 比如, 針對我們的BI系統. 晚間的ETL執行過程完成之後, 基本不會再修改dba_extents表, 這時如果我們維護一個dba_extents的映像表代替dba_extents來完成我們的查詢過程, 將是一個非常高效的替代方案.
create table perfstat.dba_extent_his
as
select * from dba_extents;
create index perfstat.ind_dba_extent_his on perfstat.dba_extent_his(block_id,blocks);
truncate table dba_extent_his;
insert into dba_extent_his
select * from dba_extents;
下述代碼描述了怎麼根據v$session_wait視圖查詢出來的等待事件參數p1,p2,p3得到實際等待的內容.
由於過程中使用到了x$底層性能表, 所以需要一點額外的操作.
create view sys.v_$ktsso
as
select * from sys.x$ktsso;
create public synonym v$ktsso for sys.v_$ktsso; --這樣將導致所有的用戶都可以訪問這裏的數據.
create view sys.v_$kglob
as
select * from sys.x$kglob;
create public synonym v$kglob for sys.v_$kglob; --這樣將導致所有的用戶都可以訪問這裏的數據.
create view sys.v_$kglpn
as
select * from sys.x$kglpn;
create public synonym v$kglpn for sys.v_$kglpn; --這樣將導致所有的用戶都可以訪問這裏的數據.
select de.owner || '.' || de.segment_name || '----' || de.partition_name object_name,
de.segment_type object_type
from perfstat.dba_extent_his de
where de.file_id = :p1
and :p2 between de.block_id and (de.block_id + de.blocks - 1)
and :event in ('db file sequential read', 'db file scattered read')
union all
select (select segment_name || '-' || partition_name
from perfstat.dba_extent_his de
where de.file_id = :p1
and :p2 between de.block_id and (de.block_id + de.blocks - 1)
) obj_name,
(select obj_type from
(select decode(ktssosegt,
1,
'SORT',
2,
'HASH',
3,
'DATA',
4,
'INDEX',
5,
'LOB_DATA',
6,
'LOB_INDEX',
'UNDEFINED') obj_type
from v$ktsso
where inst_id = userenv('instance')
and ktssoses = :saddr
and ktssosno = :serial#)
where rownum < 2) obj_type
from dual
where :event in ('direct path read','direct path write')
union all
select name obj_name, null obj_type
from v$latchname
where latch# = :p2
and :event = 'latch free'
union all
select object_name||'---'||subobject_name object_name,
chr(bitand(:p1,-16777216)/16777215) ||
chr(bitand(:p1,16711680)/65535) ||'----'|| mod(:p1,16) object_type
from dba_objects
where object_id = :row_wait_obj#
and :event = 'equeue'
union all
select (
select segment_name||'----'||partition_name
from dba_extents
where :P2 between block_id and (block_id + blocks - 1)
and file_id = :p1) object_name,
(
select segment_type ||
case when header_block = :p2 then ' header block '
when freelist_groups > 1
and :p2 between header_block + 1 and (header_block + freelist_groups) then ' freelist group block'
else ' data block' end obj_type
from
dba_segments s
where s.header_file = :p1
) object_type
from dual
where :event = 'buffer busy waits'
union all
select kglnaobj obj_name,null obj_type
from x$kglob
where inst_id = userenv('instance')
and kglhdadr = :P1RAW
and :event = 'library cache pin'
2.6 library cache pin 的阻塞者
select a.sid,
a.serial#,
a.username,
a.paddr,
a.logon_time,
a.sql_hash_value,
b.kglpnmod
from v$session a, sys.x$kglpn b
where a.saddr = b.kglpnuse
and b.inst_id = userenv('instance')
and b.kglpnreq = 0
and b.kglpnmod not in (0, 1)
and b.kglpnhdl = :P1RAW
x$kglpn——[K]ernel [G]eneric [L]ibrary Cache Manager object [P]i[N]s
Ø desc x$kglpn
##主要用來處理library cache pin holder
Name Null? Type
----------------------------------------------------- -------- ------------
ADDR RAW(4)
INDX NUMBER
INST_ID NUMBER
KGLPNADR RAW(4)
KGLPNUSE RAW(4)
KGLPNSES RAW(4)
KGLPNHDL RAW(4)
##關聯v$session_wait中event爲library cache pin的P1RAW，再關聯v$session，可以查出sid和serial#
KGLPNLCK RAW(4)
KGLPNCNT NUMBER
KGLPNMOD NUMBER
##如果值爲3，表示爲library cache pin的holder；如果值爲0，表示爲waiter
KGLPNREQ NUMBER
##如果值爲0，表示爲library cache pin的holder；如果值爲2，表示爲waiter