2026-03-12 20:23:15

idev/undo_contention.sql

@@ -0,0 +1,71 @@
+-- +----------------------------------------------------------------------------+
+-- |                          Jeffrey M. Hunter                                 |
+-- |                      jhunter@idevelopment.info                             |
+-- |                         www.idevelopment.info                              |
+-- |----------------------------------------------------------------------------|
+-- |      Copyright (c) 1998-2012 Jeffrey M. Hunter. All rights reserved.       |
+-- |----------------------------------------------------------------------------|
+-- | DATABASE : Oracle                                                          |
+-- | FILE     : undo_contention.sql                                             |
+-- | CLASS    : Undo Segments                                                   |
+-- | PURPOSE  : Undo contention report. This script is RAC enabled.             |
+-- | NOTE     : As with any code, ensure to test this script in a development   |
+-- |            environment before attempting to run it in production.          |
+-- +----------------------------------------------------------------------------+
+
+SET TERMOUT OFF;
+COLUMN current_instance NEW_VALUE current_instance NOPRINT;
+SELECT rpad(instance_name, 17) current_instance FROM v$instance;
+SET TERMOUT ON;
+
+PROMPT 
+PROMPT +------------------------------------------------------------------------+
+PROMPT | Report   : Undo Contention                                             |
+PROMPT | Instance : &current_instance                                           |
+PROMPT +------------------------------------------------------------------------+
+
+SET ECHO        OFF
+SET FEEDBACK    6
+SET HEADING     ON
+SET LINESIZE    180
+SET PAGESIZE    50000
+SET TERMOUT     ON
+SET TIMING      OFF
+SET TRIMOUT     ON
+SET TRIMSPOOL   ON
+SET VERIFY      OFF
+
+CLEAR COLUMNS
+CLEAR BREAKS
+CLEAR COMPUTES
+
+COLUMN instance_name      FORMAT a10    HEAD 'Instance'
+COLUMN class              FORMAT a18    HEADING 'Class'    
+COLUMN ratio                            HEADING 'Wait Ratio'       
+
+BREAK ON instance_name SKIP 2
+
+SELECT
+    i.instance_name                     instance_name
+  , w.class                             class
+  , ROUND(100*(w.count/SUM(s.value)),8) ratio
+FROM
+    gv$instance i
+  , gv$waitstat w
+  , gv$sysstat s
+WHERE
+      i.inst_id = w.inst_id
+  AND i.inst_id = s.inst_id
+  AND w.class IN (  'system undo header'
+                  , 'system undo block'
+                  , 'undo header'
+                  , 'undo block'
+                 )
+  AND s.name IN ('db block gets', 'consistent gets')
+GROUP BY
+    i.instance_name
+  , w.class
+  , w.count
+ORDER BY
+    i.instance_name
+  , w.class;