2026-03-12 20:23:15

idev/perf_file_io_efficiency.sql

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+-- +----------------------------------------------------------------------------+
+-- |                          Jeffrey M. Hunter                                 |
+-- |                      jhunter@idevelopment.info                             |
+-- |                         www.idevelopment.info                              |
+-- |----------------------------------------------------------------------------|
+-- |      Copyright (c) 1998-2011 Jeffrey M. Hunter. All rights reserved.       |
+-- |----------------------------------------------------------------------------|
+-- | DATABASE : Oracle                                                          |
+-- | FILE     : perf_file_io_efficiency.sql                                     |
+-- | CLASS    : Tuning                                                          |
+-- | PURPOSE  : This script produces a cumulative report that gives information |
+-- |            based on IO efficiency since the Oracle instance was started.   |
+-- |            The report generated will list physical block reads and         |
+-- |            efficiency (the efficiency number measures the percentage of    |
+-- |            time Oracle asked for and got the right block the first time;   |
+-- |            this is a function of the type of table scan and indexing).     |
+-- |                                                                            |
+-- |            The relative low efficiency of the SYSTEM areas is normal. This |
+-- |            is due to indexes and tables being mixed together in the SYSTEM |
+-- |            tablespace. A classic case on Oracle's part of "Do what we say, |
+-- |            not what we do."                                                |
+-- |                                                                            |
+-- |            * If your temporary tablespace shows an efficiency number,      |
+-- |              someone is using if for data instead of temporary tables.     |
+-- |            * Rollback efficiency should always be 100 percent; if not,     |
+-- |              someone is using the rollback tablespace for tables/indexes.  |
+-- |            * Index tablespace should always show high efficiencies; if     |
+-- |              they don't, then either the indexes are bad or someone is     |
+-- |              using the index tablespace for tables.                        |
+-- |            * An attempt should be made to even out IO. If a disk is        |
+-- |              showing a considerable amount of IO, move some of the         |
+-- |              datafiles to other disks.                                     |
+-- | NOTE     : As with any code, ensure to test this script in a development   |
+-- |            environment before attempting to run it in production.          |
+-- +----------------------------------------------------------------------------+
+
+SET LINESIZE 145
+SET PAGESIZE 9999
+
+COLUMN ts        FORMAT a15     HEADING 'Tablespace'
+COLUMN fn        FORMAT a38     HEADING 'Filename'
+COLUMN rds                      HEADING 'Reads'
+COLUMN blk_rds                  HEADING 'Block Reads'
+COLUMN wrts                     HEADING 'Writes'
+COLUMN blk_wrts                 HEADING 'Block Writes'
+COLUMN rw                       HEADING 'Reads+Writes'
+COLUMN blk_rw                   HEADING 'Block Reads+Writes'
+COLUMN eff      FORMAT a10  HEADING 'Effeciency'
+
+SELECT
+    f.tablespace_name          ts
+  , f.file_name                fn
+  , v.phyrds                   rds
+  , v.phyblkrd                 blk_rds
+  , v.phywrts                  wrts
+  , v.phyblkwrt                blk_wrts
+  , v.phyrds + v.phywrts       rw
+  , v.phyblkrd + v.phyblkwrt   blk_rw
+  , DECODE(v.phyblkrd, 0, null, ROUND(100*(v.phyrds + v.phywrts)/(v.phyblkrd + v.phyblkwrt), 2)) eff
+FROM
+    dba_data_files  f
+  , v$filestat      v
+WHERE
+  f.file_id = v.file#
+ORDER BY
+  rds
+/