2026-03-12 20:23:15

tpt/latchprof_old.sql

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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:   lhp.sql ( Latch Holder Profile )
+-- Purpose:     Perform high-frequency sampling on V$LATCHHOLDER
+--				and present a profile of latches held by sessions
+--
+-- Author:      Tanel Poder
+-- Copyright:   (c) http://www.tanelpoder.com
+--              
+-- Usage:       @latchprof <what> <sid> <latch name> <#samples>
+-- 	        	@latchprof sid,name 350 library 100000
+--	        	@latchprof name % % 1000000
+-- Other:
+--				The sampling relies on NESTED LOOP join method and having
+--				V$LATCHHOLDER as the inner (probed) table. Note that on 9i
+--				you may need to run this script as SYS as it looks like otherwise
+--				the global USE_NL hint is not propagated down to X$ base tables
+--
+--				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.
+--
+--				If you want to drill down to latch child level, uncomment the
+--				l.laddr fields from select and group by list.
+--				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 lhp_name HEAD NAME 
+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 999.999
+COL dist_samples HEAD Gets
+COL total_samples HEAD Held
+
+BREAK ON lhp_name SKIP 1
+
+WITH 
+    t1 AS (SELECT hsecs FROM v$timer),
+    samples AS (
+		SELECT /*+ ORDERED USE_NL(l.gv$latchholder.x$ksuprlat) */
+			&_lhp_what
+--		  , COUNT(DISTINCT gets)		dist_samples
+		  , COUNT(*) 					total_samples
+		  , COUNT(*) / &_lhp_samples	total_samples_pct
+		FROM 
+--			(SELECT /*+ NO_MERGE */ 1 FROM DUAL CONNECT BY LEVEL <= &_lhp_samples) s,
+	        (	SELECT /*+ NO_MERGE */ 1 FROM 
+	        		(SELECT rownum r FROM dual CONNECT BY ROWNUM <= 1000) a,
+	        		(SELECT rownum r FROM dual CONNECT BY ROWNUM <= 1000) b,
+	        		(SELECT rownum r FROM dual CONNECT BY ROWNUM <= 1000) c
+		        WHERE ROWNUM <= &_lhp_samples
+	        ) s,
+			v$latchholder l
+		WHERE
+			l.sid LIKE '&_lhp_sid'
+		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
+--  , 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,
+--  , (t2.hsecs - t1.hsecs) * 10 * s.total_samples / dist_samples / &_lhp_samples latchprof_avg_ms
+  FROM
+    t1,
+    samples s,
+    t2
+/
+