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573e876 May 15, 2018
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-- Copyright 2018 Tanel Poder. All rights reserved. More info at http://tanelpoder.com
-- Licensed under the Apache License, Version 2.0. See LICENSE.txt for terms & conditions.
--------------------------------------------------------------------------------
--
-- File name: latchprofx.sql ( Latch Holder Profiler eXtended )
-- Purpose: Perform high-frequency sampling on V$LATCHHOLDER
-- and present a profile of latches held by sessions
-- including extended statistics about in which kernel
-- function the latch held was taken
--
-- Author: Tanel Poder
-- Copyright: (c) http://www.tanelpoder.com
--
-- Usage: @latchprofx <what> <sid> <latch name> <#samples>
-- @latchprofx name 350 % 100000 - monitor all latches SID 350 is holding
-- @latchprofx sid,name % library 1000000 - monitor which SIDs hold latches with "library" in their name
-- @latchprofx sid,name,laddr % 40D993A0 100000 - monitor which SIDs hold child latch with address 0x40D993A0
-- @latchprofx sid,name,func % % 100000
-- - monitor all sessions and latches and show
-- - latch get Where info (locations in kernel code
-- - where the latch get was done)
--
-- @latchprofx sid,name,hmode,func 89 "cache buffers chains" 100000
-- - monitor functions that took latch for SID 89 only
-- - and report only "cache buffers chains" latch holders
-- - also report hold mode HMODE (shared or exclusive)
--
-- @latchprofx sid,name,hmode,func,object % 40D993A0 100000
-- - monitor for what object's access the child latch at
-- - particular address was taken. for cache buffers chains
-- - latch the object means data block address (DBA)
-- - of the block accessed in buffer cache.
-- - you can translate the 6-byte DBA to rfile#/block#
-- - using dbms_utility or dba.sql script from TPT scripts
--
-- Other:
-- This script is based on X$ tables instead of V$ tables
-- as some info required is not externalized to V$.
-- So you need to run this script either as SYS or
-- need to have relevant X$ proxy views created
--
-- The sampling relies on NESTED LOOP join method and having
-- X$KSUPRLAT as the inner (probed) table.
--
-- If sampling always reports a single latch event even though
-- many different events (or parameter values) are expected then
-- the execution plan used is not right.
--
-- The join in exec plan step 9 MUST be a NESTED LOOPS join, this is how
-- the high speed sampling is done.
--
-- -----------------------------------------------------------------------------------------------------
-- | Id | Operation | Name | E-Rows | OMem | 1Mem | Used-Mem |
-- -----------------------------------------------------------------------------------------------------
-- | 1 | MERGE JOIN CARTESIAN | | 1 | | | |
-- | 2 | MERGE JOIN CARTESIAN | | 1 | | | |
-- |* 3 | FIXED TABLE FULL | X$KSUTM | 1 | | | |
-- | 4 | BUFFER SORT | | 1 | 9216 | 9216 | 8192 (0)|
-- | 5 | VIEW | | 1 | | | |
-- | 6 | SORT ORDER BY | | 1 | 2048 | 2048 | 2048 (0)|
-- | 7 | HASH GROUP BY | | 1 | | | |
-- | 8 | NESTED LOOPS OUTER | | 1 | | | |
-- | 9 | NESTED LOOPS | | 1 | | | |
-- | 10 | VIEW | | 1 | | | |
-- | 11 | CONNECT BY WITHOUT FILTERING| | | | | |
-- | 12 | FAST DUAL | | 1 | | | |
-- |* 13 | FIXED TABLE FULL | X$KSUPRLAT | 1 | | | |
-- |* 14 | FIXED TABLE FIXED INDEX | X$KSLLW (ind:2) | 1 | | | |
-- | 15 | BUFFER SORT | | 1 | 9216 | 9216 | 8192 (0)|
-- |* 16 | FIXED TABLE FULL | X$KSUTM | 1 | | | |
-- -----------------------------------------------------------------------------------------------------
--
-- If you want to drill down to latch child level, include "name" in first parameter to latchprof
--
-- Then you can use la.sql (V$LATCH_PARENT/V$LATCH_CHILDREN) to
-- map the latch address back to latch child#
--
--------------------------------------------------------------------------------
-- what includes what columns to display & aggregate and also options like latch name filtering
DEF _lhp_what="&1"
DEF _lhp_sid="&2"
DEF _lhp_name="&3"
DEF _lhp_samples="&4"
COL name FOR A35 WRAP
COL latchprof_total_ms HEAD "Held ms" FOR 999999.999
COL latchprof_pct_total_samples head "Held %" format 999.99
COL latchprof_avg_ms HEAD "Avg hold ms" FOR 999999.999
COL dist_samples HEAD Gets
COL total_samples HEAD Held
COL ksllwnam FOR A40 TRUNCATE
COL ksllwlbl FOR A20 TRUNCATE
COL objtype FOR A20 TRUNCATE
COL object FOR A17 WRAP JUST RIGHT
COL hmode FOR A12 TRUNCATE
COL what FOR A17 WRAP
COL func FOR A40 TRUNCATE
BREAK ON lhp_name SKIP 1
DEF _IF_ORA_10_OR_HIGHER="--"
PROMPT
PROMPT -- LatchProfX 2.02 by Tanel Poder ( http://www.tanelpoder.com )
COL latchprof_oraversion NEW_VALUE _IF_ORA_10_OR_HIGHER
SET TERMOUT OFF
SELECT
DECODE(SUBSTR(BANNER, INSTR(BANNER, 'Release ')+8,1), 1, '', '--') latchprof_oraversion
FROM v$version WHERE ROWNUM=1;
SET TERMOUT ON
WITH
t1 AS (SELECT hsecs FROM v$timer),
samples AS (
SELECT /*+ ORDERED USE_NL(l.x$ksuprlat) USE_NL(s.x$ksuse) NO_TRANSFORM_DISTINCT_AGG */
&_lhp_what
&_IF_ORA_10_OR_HIGHER , COUNT(DISTINCT gets) dist_samples
, COUNT(*) total_samples
, COUNT(*) / &_lhp_samples total_samples_pct
FROM
(SELECT /*+ NO_MERGE */ 1 FROM DUAL CONNECT BY LEVEL <= &_lhp_samples) s,
(SELECT ksuprpid PID, ksuprsid SID, ksuprlnm NAME, ksuprlat LADDR, ksulawhr,
TO_CHAR(ksulawhy,'XXXXXXXXXXXXXXXX') object
&_IF_ORA_10_OR_HIGHER , ksulagts GETS
&_IF_ORA_10_OR_HIGHER , lower(ksuprlmd) HMODE
FROM x$ksuprlat) l,
(SELECT
indx
, ksusesqh sqlhash
, ksusesql sqladdr
&_IF_ORA_10_OR_HIGHER , ksusesph planhash
&_IF_ORA_10_OR_HIGHER , ksusesch sqlchild
&_IF_ORA_10_OR_HIGHER , ksusesqi sqlid
FROM x$ksuse) s,
(SELECT indx,
ksllwnam func, ksllwnam,
ksllwlbl objtype, ksllwlbl
FROM x$ksllw) w
WHERE
l.sid LIKE '&_lhp_sid'
AND l.ksulawhr = w.indx (+)
AND l.sid = s.indx
AND (LOWER(l.name) LIKE LOWER('%&_lhp_name%') OR LOWER(RAWTOHEX(l.laddr)) LIKE LOWER('%&_lhp_name%'))
GROUP BY
&_lhp_what
ORDER BY
total_samples DESC
),
t2 AS (SELECT hsecs FROM v$timer)
SELECT /*+ ORDERED */
&_lhp_what
, s.total_samples
&_IF_ORA_10_OR_HIGHER , s.dist_samples
-- , s.total_samples_pct
, s.total_samples / &_lhp_samples * 100 latchprof_pct_total_samples
, (t2.hsecs - t1.hsecs) * 10 * s.total_samples / &_lhp_samples latchprof_total_ms
-- , s.dist_events
&_IF_ORA_10_OR_HIGHER , (t2.hsecs - t1.hsecs) * 10 * s.total_samples / dist_samples / &_lhp_samples latchprof_avg_ms
FROM
t1,
samples s,
t2
WHERE ROWNUM <= 20
/
COL name CLEAR
COL hmode CLEAR
COL what CLEAR
COL func CLEAR
COL objtype CLEAR