Statspack is a set of performance monitoring and reporting utilities provided by Oracle for Oracle8i and above. A user is automatically created by the installation script - this user, PERFSTAT, owns all objects needed by this package. For more information about Statspack, read the documentation in file $ORACLE_HOME/rdbms/admin/spdoc.txt.



Install Statspack

To install the package, either change to the ORACLE_HOME rdbms/admin directory, or fully specify the ORACLE_HOME/rdbms/admin directory when calling the installation script, SPCREATE.

To run the installation script, you must use SQL*Plus and connect as a user with SYSDBA privilege. For example, start SQL*Plus, then:

On UNIX : SunOS/HP UX/Linux

SQL> CONNECT / AS SYSDBA

SQL> @?/rdbms/admin/spcreate

On Windows: XP/NT/2000/2003

SQL> CONNECT / AS SYSDBA

SQL> @%ORACLE_HOME%rdbmsadminspcreate

The SPCREATE install script runs three other scripts. These scripts are called automatically, so you do not need to run them:

* SPCUSR: Creates the user and grants privileges

* SPCTAB: Creates the tables

* SPCPKG: Creates the package

Configuring Statspack

How to locate the current Ststapack level?

- Look at table PERFSTST.STATS$SNAPSHOT

or

- Run spreport.sql and you will notice it alongwith the snapids listed

STATS$SNAPSHOT will show level for each Snapshot recorded

Change Level

execute statspack.snap (i_snap_level=> 7, i_modify_parameter=>'true');

Levels >= 0 General Performance Statistics

Levels >= 5 Additional Data: SQL Statements

Levels >= 6 Additional Data: SQL Plans and SQL Plan Usage

Levels >= 10 Additional Statistics: Parent and Child Latches

Using Statspack (gathering data)

sqlplus perfstat

--

-- Take a performance snapshot

--

execute statspack.snap;

--

-- Get a list of snapshots

--

column snap_time format a21

select snap_id,to_char(snap_time,'MON dd, yyyy hh24:mm:ss') snap_time

from sp$snapshot;

--

Running a Performance report

--

-- Run the Statspack report:

--

@?/rdbms/admin/spreport.sql

Locate Hard hitting SQL from Statpack Reposistory

1. Login as PERFSTAT user on database.

It won't work unless U login as PERFSTAT user.

2. Find DBID using

"select dbid from stats$sql_summary"

3. Locate MIN(SNAP_ID) pBgnSnap & MAX(SNAP_ID) pEndSnap from

select min(snap_id),max(snap_id),min(snap_time),max(snap_time) from stats$snapshot

where to_number(to_char(snap_time,'HH24')) > 10 and to_number(to_char(snap_time,'HH24')) < 13 and trunc(snap_time)=trunc(sysdate)

Show All SQL Stmts ordered by Logical Reads

select

e.hash_value "E.HASH_VALUE"

, e.module "Module"

, e.buffer_gets - nvl(b.buffer_gets,0) "Buffer Gets"

, e.executions - nvl(b.executions,0) "Executions"

, Round( decode ((e.executions - nvl(b.executions, 0)), 0, to_number(NULL)

, (e.buffer_gets - nvl(b.buffer_gets,0)) /

(e.executions - nvl(b.executions,0))) ,3) "Gets / Execution"

, Round(100*(e.buffer_gets - nvl(b.buffer_gets,0))/sp920.getGets(:pDbID,:pInstNum,:pBgnSnap,:pEndSnap,'NO'),3) "Percent of Total"

, Round((e.cpu_time - nvl(b.cpu_time,0))/1000000,3) "CPU (s)"

, Round((e.elapsed_time - nvl(b.elapsed_time,0))/1000000,3) "Elapsed (s)"

, Round(e.fetches - nvl(b.fetches,0)) "Fetches"

, sp920.getSQLText ( e.hash_value , 400) "SQL Statement"

from stats$sql_summary e

, stats$sql_summary b

where b.snap_id(+) = :pBgnSnap

and b.dbid(+) = e.dbid

and b.instance_number(+) = e.instance_number

and b.hash_value(+) = e.hash_value

and b.address(+) = e.address

and b.text_subset(+) = e.text_subset

and e.snap_id = :pEndSnap

and e.dbid = :pDbId

and e.instance_number = :pInstNum

order by 3 desc

Show SQL Stmts where SQL_TEXT like '%'

select

e.hash_value "E.HASH_VALUE"

, e.module "Module"

, e.buffer_gets - nvl(b.buffer_gets,0) "Buffer Gets"

, e.executions - nvl(b.executions,0) "Executions"

, Round( decode ((e.executions - nvl(b.executions, 0)), 0, to_number(NULL)

, (e.buffer_gets - nvl(b.buffer_gets,0)) /

(e.executions - nvl(b.executions,0))) ,3) "Gets / Execution"

, Round(100*(e.buffer_gets - nvl(b.buffer_gets,0))/sp920.getGets(:pDbID,:pInstNum,:pBgnSnap,:pEndSnap,'NO'),3) "Percent of Total"

, Round((e.cpu_time - nvl(b.cpu_time,0))/1000000,3) "CPU (s)"

, Round((e.elapsed_time - nvl(b.elapsed_time,0))/1000000,3) "Elapsed (s)"

, Round(e.fetches - nvl(b.fetches,0)) "Fetches"

, sp920.getSQLText ( e.hash_value , 400) "SQL Statement"

from stats$sql_summary e

, stats$sql_summary b

where b.snap_id(+) = :pBgnSnap

and b.dbid(+) = e.dbid

and b.instance_number(+) = e.instance_number

and b.hash_value(+) = e.hash_value

and b.address(+) = e.address

and b.text_subset(+) = e.text_subset

and e.snap_id = :pEndSnap

and e.dbid = 2863128100

and e.instance_number = :pInstNum

and sp920.getSQLText ( e.hash_value , 400) like '%ZPV_DATA%'

order by 3 desc

How to retrieve entire SQL + Execution PLAN from Statspack for a table

To retrieve SQL plan you need to have statspack working on level 7

1. sprepsql.sql

The SQL report (sprepsql.sql) is a report for a specific SQL statement. The SQL report is usually run after examining the high-load SQL sections of the instance health report.The SQL report provides detailed statistics and data for a single SQL statement (as identified by the Hash Value in Statspack report).

2. Hash Value is known

- Select * from STATS$SQLTEXT where hash_value='%from stats pack%' order by piece;

- For an Object first locate the OBJECT_ID

select * from sys.obj$ where name='TRANSACTION'

select snap_time

snap_id,

plan_hash_value,

OBJECT# ,

OBJECT_NAME ,

OPERATION ,

OPTIONS ,

COST ,

IO_COST ,

CARDINALITY ,

POSITION ,

CPU_COST ,

OPTIMIZER ,

SEARCH_COLUMNS ,

BYTES ,

DISTRIBUTION ,

TEMP_SPACE ,

ACCESS_PREDICATES ,

FILTER_PREDICATES

from stats$SQL_PLAN a , STATS$SNAPSHOT b where object#='&&OBJECT_ID' and a.snap_id=b.snap_id;

http://www.OracleDbaSupport.co.uk is a blog site of Sagar Patil, an independent oracle consultant with a great understanding of how the Oracle database engine & Oracle Applications work together.

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