Oracle DBA Best Practices

UTOUG Training Days 2004

Advanced DBA Best Practices

Michael S. Abbey

The Pythian Group

[email protected]

2Michael S. Abbey – Advanced DBA Best Practices

• Preamble / raison d'être

• Monitoring

• INIT.ora

• Do not wait for waits

• Integrity of your backups

Agenda

DBA Best

Practices

WOW!!UTOUG

March

2004


Agenda

• Infrastructure setup• Schema environments• Cost-based optimizer• Distributed computing• Application tuning

DBA Best

Practices

WOW!!UTOUG

March

2004


Agenda

DBA Best

Practices

WOW!!

• Working with Oracle Support Services

• Hodge podgeUTOUG

March

2004


• It's so hard to tune– Cryptic?

– Too many areas?

– Too complex?

• It’s so easy to tune– Separate components

– Version compatibility

– Concept carry-over

Memory

I/O

Apps

Preamble / raison d'êtreCryptic Too many areas


• Terminology is portable across version

• Same background processes

• Method rather than guesswork– Ripple affect

– Fix this / break that

• Instance parameters– v$parameter

– v$instance

• SQL statement– v$sqlarea

– v$sqltext

• Memory structures– v$librarycache

Preamble / raison d'êtreFacts about the Oracle Server


• Tune Apps

• Tune Memory

• Tune I/O

Turn this

Preamble / raison d'êtreToo complex??


Into this!!!!!

Preamble / raison d'êtreFacts about the Oracle Server


Monitoring

Best practices NOW will payoff down the road


You would not believe what the guy at Training Days told me. He said that his approach to

monitoring was to ignore situations that he did not deem to be necessary!

One person's approach to monitoring may not be the other person's style. Suggestions? Be my guest.

Caveat


Ensure your space monitoring traps ALL space

deficiency situations


MonitoringThe dba_free_space poltergeist

select distinct a.tablespace_name

from dba_tablespaces a,

dba_free_space b

where a.tablespace_name =

b.tablespace_name;

TABLESPACE_NAME------------------------------AD_DATAAD_INDEXRBSSYSTEMTEMP

select distinct a.tablespace_name

from dba_tablespaces a,

dba_free_space b

where a.tablespace_name =

b.tablespace_name (+);

TABLESPACE_NAME------------------------------AD_DATAAD_INDEXBLINKYRBSSYSTEMTEMP


set pages 100

col ts_name form a20 head 'Tablespace'

col pieces form 9990 head 'Pcs'

col ts_size form 999,990 head 'SizeMb'

col largestpc form 999,990 head 'LrgMB'

col totalfree form 999,990 head 'FreeMb'

col pct_free form 990 head '%Free'

col whatsused form 999,990 head 'Used'

col pct_used form 990 head '%Used'

col problem head 'Prob??'

spool umcdbp1

. . .

spool off

Da code goes hereDa code goes here

Environment

MonitoringI'm too full


select q2.other_tname ts_name, pieces, ts_size ts_size,

nvl(largest_chunk,0) largestpc, nvl(total_free,0) totalfree,

nvl(round((total_free/ts_size)*100,2),0) pct_free,

ts_size-total_free whatsused,

nvl(100-round((total_free/ts_size)*100,2),100) pct_used,

decode(nvl(100-round((total_free/ts_size)*100,0),100),

85,'+',86,'+',87,'+',88,'+',89,'++',90,'++',91,'++',

92,'++',93,'++',94,'+++',95,'+++',96,'+++',97,'++++',

98,'+++++',99,'+++++',100,'+++++','') problem

from (select dfs.tablespace_name,count(*) pieces,

round(max(dfs.bytes)/1024/1024,2) largest_chunk,

round(sum(dfs.bytes)/1024/1024,2) total_free

from dba_free_space dfs group by tablespace_name) q1,

(select tablespace_name other_tname,

round(sum(ddf2.bytes)/1024/1024,2) ts_size

from dba_data_files ddf2 group by tablespace_name) q2

where q2.other_tname = q1.tablespace_name(+) order by nvl(100-round((total_free/ts_size)*100,0),100) desc;

Code

MonitoringI'm too full


• Percentage based on– Growth patterns

– Past experiences

– Archival habits

• Ignore or not ignore– Rollback segments

– Temp

– Non-app related

• LM tablespaces with extent management local …uniform size …

• The dba_free_space poltergeist

Infrastructure issues

More of a than anything else

MonitoringThresholds


Ensure you trap potential object extension problems before your applications


• Less free space available than potential object extension • Objects within 5 extents of their maximum

MonitoringUnable to extend

col owner form a5 head Ownercol segment_type form a5 head Typecol segment_name form a24 head Namecol next_extent form 999,999,990 head NextEXTcol max_extents form 9,999 head MaxEXTcol extents form 9,999 head CurrEXT

break on owner on segment_type


MonitoringUnable to extend – available extents

promptprompt Objects that cannot extend ...prompt

select owner,segment_type,segment_name,next_extent from sys.dba_segments ds where segment_type in ('TABLE','INDEX') and next_extent > (select max(bytes) from sys.dba_free_space dfs where dfs.tablespace_name = ds.tablespace_name) order by 1,2,3;


MonitoringUnable to extend – within 5

promptprompt Objects within 5 of max extents ...prompt

select owner,segment_type,segment_name,max_extents,extents from sys.dba_segments ds where segment_type in ('TABLE','INDEX') and max_extents - extents <= 5;

• Avoid maxextents unlimited – will never detect objects with too many extents

• Number arbitrary -- based on DBA experiences


Ensure you are fluent with monitoring locally managed

tablespaces


• Locally managed [permanent] – Extent management LOCAL in DBA_TABLESPACES– Free space tracked in data files by DBA_FREE_SPACE

as well– What’s the deal then with locally managed??

• Locally managed temporary– TEMP segment cleanup not one of Oracle’s “strengths”– Easy way to track space released by segments– Easy way to see progress of TEMP-related operations

MonitoringLocally managed is what!!


MonitoringLocally managed temp

• Use V$TEMP_FILE and V$TEMP_SPACE_HEADER

• Useful to assess cleanup of temporary segments

col trname form a23 head Filecol tablespace_name form a7 head TSNamecol bytes form 9,999,999,990col bytes_free like bytes


select tsh.tablespace_name, '..'||substr(tf.name,length(name)-23) trname, tf.bytes,tsh.bytes_freefrom v$tempfile tf, v$temp_space_header tshwhere tf.file# = tsh.file_id;

TS Name File BYTES BYTES_FREE-------- ----------------------- -------------- --------------LOC_TEMP ../od01/loc_temp01.dbf 2,098,200,576 1,887,436,800LOC_TEMP ../od02/loc_temp02.dbf 2,098,200,576 1,258,291,200LOC_TEMP ../od04/loc_temp03.dbf 2,098,200,576 1,887,436,800LOC_TEMP ../od02/loc_temp04.dbf 2,098,200,576 1,887,436,800

MonitoringLocally managed temp


Ensure you protect what precious space exists in the

SYSTEM tablespace


select username from dba_users where temporary_tablespace = 'SYSTEM';

select username from dba_users where default_tablespace = 'SYSTEM';

MonitoringOuta SYSTEM buddy!!

• SYSTEM is the last place you can afford object extension

• SOURCE$ and OBJ$ love space

What did your DBA tell you??

I would never use SYSTEM!!

I hope no-one noticed I used SYSTEM – it can't happen here


Ensure you are in synch with the status of your

rollback segments


• ORA-01552: cannot use system rollback segment for non-system tablespace GRID

• ONLINE is the only acceptable status• needs recovery or full are a problem• Assumes your utility segment is in SYSTEM

tablespace

MonitoringRollback segments

select segment_name from dba_rollback_segs where status <> 'ONLINE' and tablespace_name <> 'SYSTEM';

RBS01


Detect problems with your job stream before it plagues your application operations


• Of interest to the monitoring exercise– What the job does– How often it runs – When it last ran – When it will run next

• Is the job broken– By Oracle or deliberately

dba_jobs

dba_jobs_running

MonitoringThe job stream


select schema_user||','||job||','|| to_char(last_date,'mmdd hh24:mi:ss') from dba_jobs where broken='Y' or (last_date < sysdate - 20/(24*60)20/(24*60)

INTERVAL

Exclusions– and what <> 'abcdefghi';– and job not in (210,222,388);– and instr (replace (lower(interval, ' ',null)) <> 'sysdate+1';

MonitoringJob run details


• Broken jobs seem to magically fix themselves

• Broken job auto fix (next run)create or replace procedure fj (inter in number) is cursor jobstofix is select job,what from user_jobs where last_date > sysdate-inter/1440 and broken = 'Y'; begin for jobrec in jobstofix loop dbms_job.run(jobrec.job); end loop; end;/

Smarts to ensure you do not un-break what is supposed to be broken

MonitoringUnbreakable


Ensure unusable index partitions are caught by

you, not your apps


select 'alter index '||owner||'.'||index_name|| ' rebuild partition '||partition_name||';' from dba_ind_partitions where status= 'UNUSABLE';

MonitoringUnusable index partitions

Automagically, index partitions are marked unusable

• Aborted direct path Loader sessions• Some partition maintenance operations local• Partition maintenance operations global


3 "L" words – locks & latches turn into lousy

performance if not detected early


• Two sessions vying for the same resource

• catblock.sql – rdbms/admin• Assortment of cryptic lock

views• Narrow down sessions and

convert to OS pid using v$session and v$process

paddr

spid

addr

v$sessionv$session

v$processv$process

MonitoringLocks


• The DBA's nightmare

• Low level serializable mechanisms designed to protect global data structures in the SGA

• Life expectancy sub-second

• Latches are to memory as locks are to disk

MonitoringLatches


col Requests form 999,999,999,990 head 'Requests'

col PctMiss form 99.90 head 'PCTMiss'

select name,gets+misses Requests,

round(misses/decode(gets+misses,0,-1,

gets+misses)*100,2) PctMiss

from v$latch

where misses/decode(gets+misses,0,-1,gets+misses)*100 > 10

order by gets desc;

MonitoringLatches


select count(*) from x$kglpn;

X:Y

Absolute over a certain amount (static)

Relative compared to the norm

MonitoringLatches


• A healthy environment returns counts well under 200

• Spinning for latches to gain access to precious resources

• Tempting to increase latch counts

• Low level supervisory mechanism would not allow

MonitoringLatches


Detect spikes in system load that affect performance


#!/bin/kshtypeset -i THRESHOLDtypeset -i LOADHOUR=$(date +%H)if (( $HOUR > 7 && $HOUR < 17 )); then THRESHOLD=$1else THRESHOLD=$2fitmpuptime=`uptime`tmploads=${tmpuptime##*average:}LOAD=${tmploads%%.*}if (( $LOAD > $THRESHOLD )); then echo "Load of $LOAD exceeded threshold of $THRESHOLD" exit 1fiexit 0

MonitoringSystem load


Detect devices with low free space


#!/bin/ksh

# $1 - the filesystem to check

# $2 - the byte count threshold

typeset -i bytesused

typeset -i pctused

pctused=$(df -k |grep $1 | awk '{print $5}' | sed 's/%//')

bytesused=$(df -k |grep $1 | awk '{print $4}')

if (( $bytesused < $2 ))

then print $1 is $pctused% full, PROBLEM.

fi

MonitoringDisk usage

Some locations are crucial to

backups exports archived redo logs


SQL statement contention is a sibling of latch

contention


• Concurrent executions

• Location of data

• Clustering

• Default RS locking mode

MonitoringSQL statement contention


select 'Too many sessions ( '||to_char(count(*))||' running '

substr(sql_text,1,80) query

from v$session s, v$sqlarea sa

where s.sql_address = sa.address

and s.sql_hash_value = sa.hash_value

and s.status = 'ACTIVE'

and s.audsid != 0

and sql_text not like 'select sql_text%'

group by substr(sql_text,1,80)

having count(*) > 100;

MonitoringSQL statement contention


Why do you think Oracle writes that alert log

anyways?


• Per instance• Significant errors• Lots of meaningless

gobbledygook• Establish a marker

– Read on

– Set new marker

• Ignore list

00600 00604 0651203113 07445 0165901142 0114601598 01545

Err on the side of the client—if the pages are not necessary, add to the exclude list.

MonitoringAlert log


Who discards the state of those packages anyways?


• SYS and SYSTEM– Expect DBMS_ invalid

packages

– Run dbmsxxxx,sql & prvtxxxx.plb

– Interdependencies cause one to invalidate other

• DBA_DEPENDENCIES

oracle> grep –il dbms_job *sqla0800150.sqlcatjobq.sqldbmsjob.sqle0800150.sqlstatsauto.sqlstatscusr.sqlstatspack.sqloracle> sqlplus /nolog

SQL> connect / as sysdba. . .SQL> @dbmsjob. . .. . .SQL> @prvtjob.plb

MonitoringInvalid objects


Ensure you standby your standby


MonitoringStandby database – is it up?typeset -i LINESexport log_history=\$log_historyecho "connect / as sysdba desc v$log_history exit"| sqlplus -s /nolog > recid.logLINES=`grep RECID recid.log|wc -l`if (( $LINES = 0 ))then echo Standby down exit 1else echo Standby OK exit 0fi

But I'm still on 8, what should I do??

Replace line 1 with internal, and get rid of the /nolog!


MonitoringStandby database – is it up-to-date?

typeset -i CHECKER

export log_history=\$log_history

CHECKER=`echo "connect / as sysdba

set echo off feed off pages 0

select (sysdate-(max(first_time)))*24 from v$log_history;" | sqlplus –s /nolog`if (( $CHECKER > 1 ))

then

echo Recovery older than 1 hour

exit 1

else

echo OK

exit 0

fi


MonitoringIs standby useable?

• Do an a regular basis• Weekly, bi-weekly,

every 48 hours?• Script and inspect

output• Significant output

(dual??)

echo "/ as sysdbaalter database open read only;describe dual;shutdown immediatestartup nomount;alter database mount standby database;" | sqlplus -s > roc.logLINES=`grep DUMMY roc.log|wc -l`if [ $LINES = 1 ]then echo OK exit 0else echo Problem @standby ... exit 1fi

Only required for 8i

*

*


MonitoringDirect inserts on master

All transactions propagated from master to standby via archived

redo logs.

Direct inserts not logged!

This is a problem on the standby, so ya'd better

watch out!

alter session enable parallel dml;

alter table mailer nologging;

insert into mailer

select /*+ parallel (mailer,2) */

* from mailer@hasek;

commit;

On master, there is no undo or redo for these inserts!

Beware or else


MonitoringDirect inserts on master

• mailer table on master row count = 12,345,781 on July 12

• 77,999,201 rows created in mailer on master on July 12

• Standby database activated due to disaster on July 13

select num_rows

from user_tables

where table_name = 'MAILER';

NUM_ROWS

------------

13889778

Over-simplified, but the gist of the problem.


MonitoringDetection of nologging activities

Resolution Babette

col tablespace_name form a20 head 'Tablespace'

col file_name form a30 head 'File'

col tablespace_name form a20 head 'Tablespace'

col unrecoverable_time form a20 head 'Change Time'

select ddf.file_name,ddf.tablespace_name,

vd.unrecoverable_time

from sys.dba_data_files ddf,v$datafile vd

where ddf.file_name = vd.name

and nvl(vd.unrecoverable_time,trunc(sysdate+10)) >

to_date('&1','DD-MON-YYYY');


Ensure statistics exist for CBO and they are current


MonitoringTable statistics

-- Not analyzedselect owner,table_name from sys.dba_tables where owner not in ('SYS','SYSTEM') and nvl(num_rows,0) = 0 or last_analyzed is null;

-- Not analyzed for pre-determined number of daysselect owner,table_name from sys.dba_tables where owner not in ('SYS','SYSTEM') and last_analyzed is not null and trunc(last_analyzed) < trunc(sysdate)-5;


Make sure YOU are not the bottleneck


MonitoringThe real story

• dba_ and user_ views are expensive• Learn your way around the x$ tables• With credit to Steve Adams (ixora)

– Build x_$ views to match their corresponding x$ views

– Grant select to public– Reference these views using sys.

{view_name}


set pages 0 lines 999 trimsp on echo off ver off feed off

spool xdollars

select 'create view x_$'||substr(table_name,3)||

' as select * from '||table_name||';'

from user_tables

where table_name like 'X$%';

spool off

set echo on feed on

spool xdollars.log

@xdollars.lst

spool off

Monitoring The real story


Monitoring Dollar signs

• Familiarize yourself with the v$ views• Available when database mounted and not

open• Column names inconsistent with dba_

counterpartsselect table_name

from dict

where table_name like 'V$%'

order by 1;


Monitoring Roadmap to $#

select ds.owner, ds.segment_name, ds.partition_name, ds.segment_type,. . . from sys.uet$ e, sys.sys_dba_segs ds, sys.file$ f. . .select /*+ ordered use_nl(e) use_nl(f) */. . . from sys.sys_dba_segs ds, sys.x$ktfbue e, sys.file$ f

DONE


select u.name, o.name, o.subname,. . . from sys.user$ u, sys.obj$ o, sys.ts$ ts, sys.sys_objects so, sys.seg$ s, sys.file$ f. . .select u.name, un.name, NULL,. . . from sys.user$ u, sys.ts$ ts, sys.undo$ un, sys.seg$ s, sys.file$ f. . .select u.name, to_char(f.file#)||'.'||to_char(s.block#),. . . from sys.user$ u, sys.ts$ ts, sys.seg$ s, sys.file$ f

Monitoring sys_dba_segs


select . . . from sys.tab$ tselect . . . from sys.tabpart$ tpselect . . . from sys.clu$ cselect . . . from sys.ind$ iselect . . . from sys.indpart$ ipselect . . . from sys.lob$ lselect . . . from sys.tabsubpart$ tspselect . . . from sys.indsubpart$ ispselect . . . from sys.lobfrag$ lf

Monitoring This is the end


MonitoringCaveat at upgrade time

It's changed in the next release


MonitoringSo many alerts!!


The autoextensible black hole revealed


• Default for many installations

• 2 serious issues when requested extension– over 2Gb limit– cannot be physically accommodated one device

• Oracle is known to not do a very good job of recovering from aborted autoextension

• Cleanup after abend not handled well

MonitoringAutoextension



create table aemon ( file_name varchar2(30), sdate date bytes number);

insert into aemon select file_name,sysdate,bytes from dba_data_files where autoextensible = 'YES';



select fst.file_name, fst.bytes, fsy.bytes,

round((fst.bytes-fsy.bytes)/fsy.bytes *100,2)

from aem fsy, aem fst

where fst.file_name = fsy.file_name

and trunc(fst.sdate) = trunc(sysdate)

and trunc(fsy.sdate) = trunc(sysdate-1)

and fst.bytes > fsy.bytes;


• Connection testing• Anticipate common

problematic areas• Be thorough and pro-

active• Email gateway• Share the load

• Page and/or email• Document via some

form of tracking system

• MetaLink MetaLink MetaLink MetaLink MetaLink MetaLink

MonitoringBest practices


INIT.ora



INIT.ora

• Organization• Compatibility• Shared pool• Ramifications• Undocumented

parameters


INIT.ora must be clean and readable


• Not a fan of ifile

• Alphabetical ordersort < initumc.ora > sio

cp sio initumc.ora

rm sio

• Toggles stay in place

• Comment changes

• Clean up dbs directory– What is soxx??

Significant defaults– Hard-code– Movements between

versions

• Show parameters

INIT.oraOrganization


• Hard-code– Surprises during

upgrades

– Are you going far enough

• New features– Can I use them?

– Can I go back?

• Access to new features• Changed behaviour of

old features

INIT.oraCompatibility


Wading through the shared pool


• Increasing demands as version increases

• CURSOR_SHARING in 8.1.6 is a big deal– Default is EXACT

– Preferred is FORCE

– Linux 8.1.7

– Alpha 8.1.6

• Bigger is not always better• 4031 errors centre around

4096– _shared_pool_reserved_min_alloc

at 4000• Flushing the pool

– Manual or transparently– A double-edged sword

• Get yourself in a bind

INIT.oraShared pool


INIT.ora

HAR


Aware of ramifications when changing values


INIT.oraRamifications of higher values

set shmsys:shminfo_shmmax=4294967295set shmsys:shminfo_shmmin=1set shmsys:shminfo_shmmni=100set shmsys:shminfo_shmseg=10set semsys:seminfo_semmni=100set semsys:seminfo_semmsl=500set semsys:seminfo_semmns=500set semsys:seminfo_semopm=1000set semsys:seminfo_semvmx=32767

DB_CACHE_SIZE

LARGE_POOL_SIZE

SHARED_POOL_SIZE

OPEN_CURSORS

PROCESSES

• Semaphores are advisory locking mechanisms that ensure a server completes certain tasks before beginning another.

• Some parameter values drain semaphores and others look for larger portions of shared memory


More than meets the eye


INIT.oraUndocumented parameters

x$ksppi Name Type

--------- ----------------

ADDR RAW(4)

INDX NUMBER

INST_ID NUMBER

KSPPINM VARCHAR2(64)

KSPPITY NUMBER

KSPPDESC VARCHAR2(64)

KSPPIFLG NUMBER

x$ksppcv Name Type

----------- --------------

ADDR RAW(4)

INDX NUMBER

INST_ID NUMBER

KSPPSTVL VARCHAR2(512)

KSPPSTDF VARCHAR2(9)

KSPPSTVF NUMBER

KSPPSTCMNT VARCHAR2(255)


INIT.oraUndocumented parameters

select ksppinm,ksppstvl,ksppdesc

from x$ksppi x,x$ksppcv y

where x.indx = y.indx

and translate(ksppinm,'_','#') like '#%' order by 1

KSPPINSM KSPPSTVL KSPPDESC

-------------------------------- --------- ---------------------------------

_allow_resetlogs_corruption FALSE allow resetlogs even if it

will cause corruption

_corrupted_rollback_segments corrupted undo segment list

_db_handles_cached 5 Buffer handles cached each process

_shared_pool_reserved_min_alloc 4400 minimum allocation size in bytes

for reserved area of shared pool


• Readable is crucial• Comment changes• Cleanup the dbs

directory• Be familiar with

memory consumers• Semaphore limitations

• Familiarize yourself with dynamic memory structures in 9i

• Block size caches 9i• Watch out for

shared_pool_size > 90000000

INIT.oraBest practices

Issues Rich


Do not wait for WAITs



Are wait situations detracting from overall

performance?


Do not wait for WAITs

• Wait situations are the biggest performance detractor

• Latches—protect the integrity of shared memory structures.

• Locks—protect the integrity of your data.

• V$ dynamic performance views:– v$waitstat– v$session_wait

• DBA_ views– dba_blockers

(catblock.sql)


select event,count(*),sum(seconds_in_wait) siw from v$session_wait group by event;

EVENT COUNT(*) SIW--------------------------- -------- ---------

SQL*Net message from client 1192 747,039SQL*Net message to client 2 0db file sequential read 5 0log file parallel write 1 0pmon timer 1 9,062rdbms ipc message 24 128smon timer 1 908

Do not wait for WAITsv$session_wait


Where has all the CPU gone?


• Map running SQL to user sessions

• Zero in on CPU consumers

select sql_text, sid, serial#

from v$session s, v$sqlarea sa

where s.sql_address = sa.address

and s.sql_hash_value = sa.hash_value

and s.status = 'ACTIVE'

and s.audsid != 0

and sql_text not like 'select sql_text%';

Do not wait for WAITsWho's doing what


Do not wait for WAITsRelationship to system load

• Get a handle on "normal" system load using uptime command

• Spool to log file in the crontab, running every 5 minutes

*/5 /oracle/bin/uptime.sh >> /oracle/logs/uptime.sh.log 2>&1

• High load averages almost always map to wait situations SQL*Net message from client

db_file sequential readdb file scattered read


set charwidth 17

select lpad(' ',3*(level-1))||waiting_session,

waiting_session,lock_type,mode_requested,

mode_held,lock_id1,lock_id2

from lock_holders

connect by prior waiting_session = holding_session

start with holding_session is null;

WAITING_SESSION TYPE MODE REQUESTED MODE HELD LOCK ID1 LOCK ID2

----------------- ---- ----------------- ----------------- -------- --------

553 NONE None None 0 0

213 TX Share (S) Exclusive (X) 34888 39

378 RW Exclusive (X) S/Row-X (SSX) 33255666 2

3928 RW Exclusive (X) S/Row-X (SSX) 3255666 2

Do not wait for WAITsutllockt.sql


• Waiting drains system resources

• Wait events cause destructive spinning

• Minimizing potential waits foremost in your minds

• Commit often

• SQL statement contention

• Concurrent user requests for the same data in the cache

• DO not exploit multi-tasking

Do not wait for waitsBest practices

Issues Rich


Integrity of your backups



Integrity of your backups

Media recovery enabled (archivelog mode)

1. Image backups

2. Export– No indexes / No

constraints

– No rows

3. Control file

5. INIT.ora

6. listener.ora

7. tnsnames.ora

Assume these are run nightly


Backup is nada without integrity and recovery

testing


Best case scenario• Separate server to restore image• Deliberate complete media recovery

– recover database . . .– recover datafile . . .– recover tablespace . . .

• Deliberate incomplete recovery at the database level

Integrity of your backupsImage backups


• Mock disaster recovery• Ideally on the same machine

– With no downtime, involves an ORACLE_SID change

• using backup controlfile is not the Real McCoy

– Plan during a window of opportunity

• Make sure you have performed the recovery portion of your image is NOT tested



• NFS device is no substitute for offline storage but …– Mount points all over the corporate server

environment– Target of all images and exports

• Run the NFS out to secondary storage

• root user buy-in



Tested rebuild from full database exports


• Create the database (see in Infrastructure section)

• Run 3 or 4 full database imports

Integrity of your backupsTest rebuild from full database export

inctype=systemonline rollback

segments just builtinctype=restore

rows=n ignore=y

rows=n ignore=y

1 2

34

Just definitions NOT data


Standby assisting checkup of recovery process


• Shutdown your standby• Re-instantiate (hot /u02/hot)

Integrity of your backupsTesting using standby technology

set pages 0 trimsp on lines 999 echo off feed off

select 'scp /u02/hot'||file_name||

' [email protected]:'||file_name

from dba_data_files;


select 'gzip –d '||file_name||'.gz'

from dba_data_files;


• Re-get standby control file

• Copy to appropriate control_files = locations

alter database create standby

controlfile as 'standby.ctl';


select 'cp standby.ctl '||name

from v$controlfile;

Integrity of your backupsTesting using standby technology


Data integrity of your exports


Integrity of your backupsHow's export written

Export: Release 9.2.0.5 - Production on Sat Sep 31 16:47:52 2004

(c) Copyright 2001 Oracle Corporation. All rights reserved.

Connected to: Oracle9i Enterprise Edition Release 9.2.0.5 - Production

With the Partitioning option

JServer Release 9.2.0.5 - Production

Export done in WE8DEC character set and AL16UTF16 NCHAR character set

server uses US7ASCII character set (possible charset conversion)

• Mismatch between UNIX environment and Server character set

• Determined by NLS_LANG

Wake-upWake-up


Collège Brébeuf

Frhre Norman:

Mrs. Jelinski and I were very pleased with our visit to Collhge Bribeuf, and are pleased with what we saw. We are especially happy that we see eye to eye on the preservation of the native Francophone culture with something as simple as accent retention in our Oracle9i database!

Integrity of your backupsCharacter set conversion

Oracle9i: A Beginner's

Guide


Compression checking your export/import engine


Integrity of your backupsGee, zip?

rm export.pipe > /dev/null 2>&1mkfifo export.pipegzip < export.pipe > fulldb.dmp.gz &sleep 2exp parfile=fulldb.parfile

userid=/ full=y log=fulldb

indexes=n constraints=n

buffer=5000000 triggers=n

file=export.pipe

8i

9i

triggers=n

Usable in its compressed state?


Integrity of your backupsGee, unzip?

rm import.pipe > /dev/null 2>&1mkfifo import.pipegunzip < fulldb.dmp.gz > import.pipe &sleep 2imp userid=/ file=import.pipe full=y log=fulldb_in buffer=50000000

Better find out sooner than during a disaster recovery!!

IMP-00037: Character set marker unknownIMP-00000: Import terminated unsuccessfully

IMP-00009: abnormal end of export fileIMP-00000: Import terminated unsuccessfully


Bottom-line … can I read that export file?


Integrity of your backupsRead this, import!

imp userid=/ full=y indexfile=fulldb.sql log=fulldb_if

Import: Release 9.2.0.5 - Production on Sat Jun 30 22:13:49 2004(c) Copyright 2001 Oracle Corporation. All rights reserved.

Connected to: Oracle9i Enterprise Edition Release 9.2.0.5 - ProductionWith the Partitioning optionJServer Release 9.2.0.5 - Production

Export file created by EXPORT:V09.20.00.05 via conventional pathimport done in US7ASCII character set and AL16UTF16 NCHAR character setImport terminated successfully without warnings.


• Only 10% of the way there without testing recovery

• Full and partial components of database

• Missing archived redo logs

• Missing control file(s)• Test rebuild from

export• Test clone on another

server• Role played by your

standby

Integrity of your backupsBest practices


Infrastructure setup


Oracle

The

9i


Infrastructure setupA word on creating a database

I've been an Oracle DBA for 2,000 years (US) and

have never created a database; why start

now?? I always upgrade

No thanks, sonny, I went to a user group meeting. As soon as I got back to the office I started creating databases. I

learned SO MUCH!! You ever tried it?? You need the support

more than me!!

Please sit

No


Infrastructure setupCreating the database

• 9i Oracle Managed files by specifying– db_create_file_dest

– db_create_online_log_destn

– undo_management = auto

– undo_tablespace = rollback

– undo_retention = 2000

• Do it yourself– Create database

• controlfile• character set• maxlogfiles• maxloghistory• maxlogmembers• maxdatafiles

– Datafile

– Log file(s)create database umcundo tablespace rollbackdefault temporary tablespace temp;


Step-by-step database creation; the players


• The SYSTEM tablespace– systemnn.dbf ~ 250m– Set pctincrease 1

(later)

• Redo log groups– At least dual two-

membered groups– logmn_gn.ora (member

number / group number)

• Construct first non-SYSTEM rollback segment– Acquire 20 extents of ~

100k each

• Run admin scripts• Test creation

Infrastructure setupCreating the database yourself


startup nomountcreate database umc controlfile reuse maxlogfiles 16 maxlogmembers 2 maxdatafiles 2048 maxloghistory 1000 character set we8iso8859p1datafile '/data01/oracle/umc/dbs1_umc.dbf' size 250mlogfile group 1 ('/redo01/umc/log1_g1.dbf', '/redo02/umc/log2_g1.dbf') size 200m, group 2 ('/redo02/umc/log1_g2.dbf', '/redo01/umc/log2_g2.dbf') size 200m;

Infrastructure setupCreate database – phase 1


startup nomount

create database umc

controlfile reuse

maxlogfiles 16

maxlogmembers 2

maxdatafiles 30

maxloghistory 1000

character set

datafile '/data01/…' size 250m

logfile group 1 ('…1_g1.dbf',

'…2_g1.dbf') size 200m,

group 2 ('…1_g2.dbf',

'…2_g2.dbf') size 200m;

1

2

3

4

5

6

1. For this or create controlfile

2. Will not error out if files already exist

3. Make an artificially large #4. Do not allow to default – WE

good place to start 5. No smaller6. 2 dual membered groups

Infrastructure setupCreate database (1) – important points

http://members.arttoday.com/Left/category/tree/Main/close-up/Tmpl/index-noright.tmpl?a=c&show=all&b=k&c=&mclass=D&f_b=b&qclass=A&f_c=c&f_e=e&f_g=g&f_j=j&cols=4&q=owl&eQ=owl&f_w=w&o=755319&memlevel=C


Infrastructure setupA word on sizing online redo logs

Two choices:

1. Small online redo logs to minimize time to push to standby

2. Customary large redo logs with forced log switches



shutdown

startup

alter tablespace system default

storage (pctincrease 1);

create rollback segment rb_temp

tablespace system storage (initial

50k next 50k minextents 20 maxextents 20);

alter rollback segment rb_temp online;

http://members.arttoday.com/Left/category/tree/Main/close-up/Tmpl/index-noright.tmpl?a=c&show=all&b=k&c=&mclass=D&f_b=b&qclass=A&f_c=c&f_e=e&f_g=g&f_j=j&cols=4&q=asterisk&eQ=asterisk&f_w=w&o=879718&memlevel=A


Infrastructure setupCreate database (2) – important points

shutdown

startup

alter tablespace system default

storage (pctincrease 1);

create rollback segment rb_temp

tablespace system storage (initial 50k

next 50k minextents 20 maxextents 20);

alter rollback segment rb_temp online;

1

23

4

1. No more to be done nomount – rest of work requires instance to be open.

2. Permit pmon to automatically coalesce free space in SYSTEM

3. First non-SYSTEM rollback segment (~1Mb)

4. Rollback segments created OFFLINE by default; edit INIT.ora at the same time so you do not forget



@?/rdbms/admin/catalog

@?/rdbms/admin/catproc

@?/rdbms/admin/catrep

@?/rdbms/admin/catsnap

@?/rdbms/admin/dbmsutil

@?/rdbms/admin/prvtutil.plb

@?/rdbms/admin/dbmssql

@?/rdbms/admin/prvtsql.plb

Build the data dictionary

Install PL/SQL

Replication

Snapshot specifics

Popular utility packages

""

SQL utilities

""



Right option(s)

Version numbering EE/Standard

Expected feedback

http://members.arttoday.com/Left/category/tree/Main/close-up/Tmpl/index-noright.tmpl?a=c&show=all&b=k&c=&mclass=D&f_b=b&qclass=A&f_c=c&f_e=e&f_g=g&f_j=j&cols=4&q=check%20marks&eQ=check%2520marks&f_w=w&o=651799&memlevel=C


Infrastructure setup

Database is created

Data dictionary has been populated

First non-system rollback segment exists and is online


Infrastructure setuppupbld.sql


Fluency in rollback segment setup


Infrastructure setupRollback segments

• 4 to 6 equally-sized segments

• minextents and maxextents the same at creation time

• 500k to 2Mb extents• Not in locally managed

tablespaces• Mentioned in INIT.ora

• Large segment for large transactions– 2 to 4Gb– Larger extent size– Cap at creation time

• No guarantee unless the only one online


• Dedicated tablespace

• Appropriately named

Infrastructure setupRollback segment tablespace(s)

create tablespace rollback datafile

'/u3/oradata/umc/rollback01.dbf' size 1024m,



'/u5/oradata/umc/rollback04.dbf' size 1024m;

File names contain tablespace name.


Infrastructure setupRollback segment creation

create rollback segment rbs01 tablespace rollback storage (initial 2m next 2m minextents 499 maxextents 499);create rollback segment rbs02 tablespace rollback storage (initial 2m next 2m minextents 499 maxextents 499);create rollback segment rbs03 tablespace rollback storage (initial 2m next 2m minextents 499 maxextents 499);create rollback segment rbs04 tablespace rollback storage (initial 2m next 2m minextents 499 maxextents 499);

ROLLBACK_SEGMENTS = (rbs01,rbs02,rbs03,rbs04)


Empowering the techies with do-it-yourself


Infrastructure setupv$dba

• v$ dynamic performance views• Over 200 with 9i

– most accessible when database mounted• DBA_ dictionary views similar to their

USER_ counterparts with ownership column

• There's nothing to hide• Grant access but no public synonyms

Mother may I ??


Infrastructure setupv$dba

connect / as sysdbaset echo off pages 0 lines 999 trimsp on feed offspool veedbaselect 'grant select on '||view_name||' to public;' from user_views where view_name like 'DBA%' or view_name like 'V_$%';

• Often used here and there by applications• V$ public synonyms probably exist• Granting must be done on view, not public synonym

for V$ to avoidORA-02030: can only select from fixed tables/views


Fluency in locally managed


• Different syntax than DM counterparts

• Temporary files end up in DBA_TEMP_FILES

• Free space bitmap in datafile headers

• Reduced recursive I/O

• Extent management local– autoallocate turns

Oracle loose with extent sizing

• Objects of differing sizes

• Lots of different sized extents

– uniform size {} defaults to 1Mb

Infrastructure setupLocally managed tablespaces


Infrastructure setupLocally managed tablespaces

create tablespace loc_geo_index datafile '/u01/oradata/loc_geo_index01.dbf' size 2000m, '/u04/oradata/loc_geo_index01.dbf' size 2000mextent management local autoallocate ;

create tablespace loc_geo_index datafile '/u01/oradata/loc_geo_index01.dbf' size 2000m, '/u04/oradata/loc_geo_index01.dbf' size 2000mextent management local uniform size 20m;


Infrastructure setupLM temp tablespace

create temporary tablespace loc_temp datafile '/u01/oradata/loc_temp01.dbf' size 2000m, '/u04/oradata/loc_temp02.dbf' size 2000mextent management local uniform size 20m;

• Keep extents in TEMP below 1000• Space allocated then controls uniform size• Great deal of the work done at startup involves

reconciliation and transfer of block ids from free to unallocated (fet$ to uet$)


• Make a point of starting from the beginning (create database)

• Pay attention to each piece in the puzzle

• Completeness checking at the end

• Practice practice practice

• Do temp and rollback right

• Know your friendly neighbourhood admin scripts

Infrastructure setupBest practices


Schema Environments



Establish and follow guidelines


Schema environments Guidelines

• Thou shalt not give user an over-rich environment

• Thou shalt not sort or default to SYSTEM

• Thou shalt occupy space in appropriately-named tablespaces

• Thou shalt not have DBA, CONNECT, or RESOURCE


Smart when setting up your user environments


• Creating a user• Temporary tablespace• Use O/S authorization

for all host-based users

• Connection and privileges depend on function

create user sample identified by sx_p0 temporary tablespace loc_temp;

alter user sample identified externally;

-- Jack and Jill users

grant create session to jj_user;

Schema environments User creation


• Give necessary privileges and no moregrant create table, create view, create procedure, create trigger, create synonym, create snapshot, create database link to sample;

• Who has more than they need??

• Who has been given DBA

• Are the any privileges given out correctly?

Schema environments Application data users


select grantee, privilege -- SAMPLE is a schema from sys.dba_sys_privs -- deliberately set up to where privilege not in -- set the standard (select privilege from sys.dba_sys_privs where grantee = 'SAMPLE')UNIONselect grantee, granted_role from sys.dba_role_privs where granted_role in ('DBA','CONNECT', 'RESOURCE','EXP_FULL_DATABASE', 'IMP_FULL_DATABASE')order by 1;

Schema environments Who has more than they need??


GRANTEE PRIVILEGE------------------ -----------------------ABRAMSON DBAABRAMSOM DROP PUBLIC SYNONYMJACKSON CONNECTJACKSON RESOURCE JONES DBAREDMOND SELECT ANY TABLETHOMSON DBATHOMSON INSERT ANY TABLETHOMSON UPDATE ANY TABLEUQUART DBAUQUART UNLIMITED TABLESPACES

Schema environments Who has more than they need??


Adopt conventions that make sense


• Plan for the future

• Picture yourself at 4:15 am weeding through cryptic names

• Bind tablespace names to owner USERNAME

• Marry data and index tablespace names

Schema environments Naming conventions


• Based on USERNAME

Schema environments Naming tablespaces

• Based on function (data or index)

create tablespace DELIVERY datafile -- Data segments '/u01/oracle/oradata/delivery01.dbf' size 1024m, '/u05/oracle/oradata/delivery02.dbf' size 1024mdefault storage (initial 100m next 100, pctincrease 0);

create tablespace DELIVERYX datafile -- Index segments '/u02/oracle/oradata/deliveryx01.dbf' size 1024m, '/u03/oracle/oradata/deliveryx02.dbf' size 1024mdefault storage (initial 100m next 100, pctincrease 0);


Schema environments Naming tablespaces - violators

select distinct tablespace_name from sys.dba_segments where tablespace_name not in (owner,owner||'X') or (tablespace_name not in ('%'||owner||'%X%'||'%PTS%') or tablespace_name not in ('%'||owner||'%PTS%'));

Define rules first, implement, and track– Data segment names = USERNAME– Index segment names = USERNAME with X– Partitioned objects = USERNAME followed by

underscore ~ X for index partitions ~ PTS for partitioned tablespace


• Object name• Index non-unique or

unique indicator + sequential number

• Underscore separators• Pnnnn forcing fixed-

length names for sorts• Abbreviate carefully

• Imbed hp for hash-partitioned objects– Affects syntax for

maintenance

– Affects how operations are carried out

• Fix names after merges and splits

Schema environments Naming partitions


create table mail (originator varchar2(40), created date, . . . . . . read varchar2(1)) storage (initial 200m next 200m pctincrease 0)partition by range (created)(partition post_mail_p0001 values less than (to_date('01-JAN-2001','DD-MON-YYYY')) tablespace post_mail_pts_0001, partition post_mail_p0002 values less than (to_date('01-JUL-2001','DD-MON-YYYY')) tablespace post_mail_pts_0002, partition post_mail_p0003 values less than (to_date('01-JAN-2002','DD-MON-YYYY')) tablespace post_mail_pts_0003, . . . . . . partition post_mailing_pmax values less than (maxvalue) tablespace post_mail_pts_max);

Schema environments Data partitions


create index mail_n1 on mail (originator) (partition post_mail_n1_p0001 values less than tablespace post_mailx_pts_0001, partition post_mail_n1_p0002 values less than tablespace post_mailx_pts_0002, partition post_mail_n1_p0003 values less than tablespace post_mailx_pts_0003, . . . . . . partition post_mail_n1_pmax values less than (maxvalue) tablespace post_mailx_pts_max);

Schema environments Index partitions


Schema environments Naming indexes

2 schools of thought

Table name

N for non-unique indexesU for unique indexes

Separate series for each type

Table name

Abbreviation(s) for column(s) in index


Key index decisions


• Primary key constraints – Always name with _PK suffix– With using index are the same as unique

indexes– Allow foreign key references

Schema environments Unique index vs. constraint

alter table mailer add constraint mailer_pk

primary key (id) using index

storage (initial 300m next 300m pctincrease 0)

tablespace loc_mail_indx;


• Users allowed to do what they need and nothing more

• Segregate users by function

• Adopt and follow naming conventions

Schema environmentsBest practices

• Trap and report on violators

• 30 character limit– Abbreviate smartly– Abbreviate

consistently– Ensure all players are

aware


Distributed computing



Manage (not mis-manage) your replication

environment


Distributed computing Snapshots are a snap

• Use same name as master table• Give them storage parameters just like tables• Negotiate refresh interval• Ensure there are no premature refreshes• Existing refresh intervals . . .select job,what,interval from user_jobs where lower(what) like 'dbms_refresh%';


Distributed computing Indexes on snapshots

• Primary key snapshots preferred

• ROWID (à la Oracle7) still supported in 9i

• PK constraint created with create snapshot

• Check for secondary indexes on snapshots by referring back to master

• Do not check and forget—do so on a regular basis


Distributed computing Indexes on snapshots

create snapshot log on vendor_prod storage (initial 2m next 2m pctincrease 0) tablespace sn_logs;

create snapshot vendor_prod refresh fast start with sysdate next sysdate+10/1440as select * from vendor_prod@producttablespace loc_snaps;

On master

On remote snapshot + secondary indexes


Thoroughness of indexing your replicated objects


Distributed computing Indexes on snapshots—completeness check

col inm form a10 head Indexcol column_name form a7 head Columncol column_position form 999 head Pos

break on inm

select index_name inm,column_position,column_name from user_ind_columns where table_name = upper('&1')minusselect index_name inm,column_position,column_name from user_ind_columns@product where table_name = upper('&1') order by 1,2;


Many many listeners


Distributed computing Some port with that?

• Use different ports for different connection requests

• Separate by source– By web server– By connection type (jvm, cgi)

• Speak with the SA before choosing ports

• Must be reflected on client(s)


Distributed computing Multiple ports / multiple listeners

LISTENER1521 =

(DESCRIPTION_LIST =

(DESCRIPTION =

(ADDRESS_LIST =

(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC)))

(ADDRESS_LIST =

(ADDRESS = (PROTOCOL = TCP)(HOST = mofo1)(PORT = 1521)))))

LISTENER1522 =

(DESCRIPTION_LIST =

(DESCRIPTION =

(ADDRESS_LIST =

(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC)))

(ADDRESS_LIST =

(ADDRESS = (PROTOCOL = TCP)(HOST = mofo1)(PORT = 1522)))))

tnsnames.ora aliases must reflect right port #s


• Know how to replicate• Fundamental to the

Internet environment• Offloading of

processing crucial to life expectancy of sites with very large user community

Distributed computingBest practices

• Completeness in your replication environment

• Multiple listeners• Listener per snapshot (if

enough to go around)• Fluency with

DBMS_JOB package


Cost-based optimizer



• Collecting of statistics like – Number of rows

– Average row length

– Distinct column values

– High value / low value

• Run unattended periodically from crontab

• Frequency decisions– Consult IT personnel

– Stale statistics more harm than good

• Using SQL*Plus analyze command OR PL/SQL packages

• Inspect last_analyzed

Cost-based optimizer DBA's best-friend

B

C

O


Decisions / approaches


• analyze is not going any where (yet) with 9i and 10g

• Perform from a central user

• Preferably O/S authenticated [externally]

Cost-based optimizer Setup

B

C

O

create user analyzer identified by pw;

alter user analyzer identified externally;

grant create session to analyzer;

grant analyze any to analyzer;

We always identify

externally


Cost-based optimizer How often

• Size based– Pick a size– Treat those above threshold

differently• Usage based

– Track most frequently changed objects

– Exclude hot objects / treat differently


Ensure you begin at the beginning


• Delete statistics EVERYWHERE

• Flip or set entry in INIT.ora

• Liaise with user community

• Pick 2 or 3 days a week

• Assess run time

• Assess impact on system

Cost-based optimizer In the beginning


Cost-based optimizer Deleting statistics

set echo off pages 0 trimsp on lines 999

spool stat_del.sql

select 'exec dbms_stats.delete_schema_stats (ownname=>'||

''''||username||''''||')'

from sys.dba_users

where username not in ('SYS','SYSTEM');

spool off

set echo on feed on

spool stat_del

@stat_del

spool off


• Tables– Estimate sample {2-10}

percent– Populates USER_TABLES

• Indexes– Compute– Populates

USER_IND_COLUMNS

• Nothing short of a windfall

Cost-based optimizer Method


Always be aware of your options


Cost-based optimizer Using PL/SQL procedure

PROCEDURE GATHER_SCHEMA_STATS Argument Name Type In/Out Default? ----------------- ---------- ------ -------- OWNNAME VARCHAR2 IN ESTIMATE_PERCENT NUMBER IN DEFAULT BLOCK_SAMPLE BOOLEAN IN DEFAULT METHOD_OPT VARCHAR2 IN DEFAULT DEGREE NUMBER IN DEFAULT GRANULARITY VARCHAR2 IN DEFAULT CASCADE BOOLEAN IN DEFAULT STATTAB VARCHAR2 IN DEFAULT STATID VARCHAR2 IN DEFAULT OPTIONS VARCHAR2 IN DEFAULT OBJLIST DBMS_STATS OUT STATOWN VARCHAR2 IN DEFAULT


Four-part approach

1. Initialization parameters

2. Place objects in monitoring mode

3. Place a stake in the ground for each schema

4. Schedule regular statistic collection

I. Do not use for Oracle Applications

II. Do not use for third party apps – liaise with vendors


1 – INIT.ora


set pages 0 lines 999 trimsp on feed off

spool monon

select 'alter table '||owner||'.'||table_name||

' monitoring;'

from sys.dba_tables

where owner not in ('SYS','SYSTEM')

and nvl(duration,'X') <> 'SYS$TRANSACTION'

and nvl(iot_type,'X') <> 'IOT_OVERFLOW'

and nvl(temporary,'X') <> 'Y'

and monitoring <> 'YES';

spool off

2 - Turn on monitoring


set lines 999 trimsp on pages 0

spool sitg

select unique 'exec dbms_stats.gather_schema_stats (ownname=>'||

''''||owner||''''||',estimate_percent=>2,'||

'block_sample=>false,method_opt=>'||

''''||'for all indexed columns size 1'||

''''||',degree=>8,granularity=>'||''''||'ALL'||''''||

',cascade=>true);'

from sys.dba_tables

where owner not in ('SYS','SYSTEM');

spool off

3 – Stake in the ground


4 – Schedule regular collection

• turn on monitoring– for tables not already in monitoring mode

• gather empty– new tables created since last run– tables inadvertently taken out of

monitoring mode

• gather stale– those that have changed >= 10%


4.1 – Turn on monitoring

set pages 0 lines 999 trimsp on feed off

spool monon

select 'alter table '||owner||'.'||table_name||

' monitoring;'

from sys.dba_tables


and nvl(duration,'X') <> 'SYS$TRANSACTION'

and nvl(iot_type,'X') <> 'IOT_OVERFLOW'

and nvl(temporary,'X') <> 'Y'

and monitoring <> 'YES';

spool off


4.2 – gather empty

select unique 'exec dbms_stats.gather_schema_stats '||

'(ownname=>'||''''||owner||''''||

',estimate_percent=>1,block_sample=>false,'||

'method_opt=>'||''''|| 'for all indexed'||

' columns'||' size 1'||''''||',options=>'||

''''||'gather empty'||''''||',degree=>8,'||

'granularity=>'||''''||'ALL'||''''||

',cascade=>true);'

from sys.dba_tables



4.3 – gather stale

select unique 'exec dbms_stats.gather_schema_stats '||

'(ownname=>'||''''||owner||''''||

',estimate_percent=>1,block_sample=>false,'||

'method_opt=>'||''''|| 'for all indexed'||

' columns'||' size 1'||''''||',options=>'||

''''||'gather stale'||''''||',degree=>8,'||

'granularity=>'||''''||'ALL'||''''||

',cascade=>true);'

from sys.dba_tables



Rationalize the approach

break on owner on table_nameset pages 70col table_name form a24col partition_name form a24col owner form a16col pct form 999,999.9select a.owner,a.table_name,b.partition_name, a.num_rows, (inserts+updates+deletes)/num_rows*100 pct, last_analyzed from sys.dba_tables a,sys.dba_tab_modifications b where a.table_name = b.table_name and a.owner = b.table_owner and (inserts+updates+deletes)/num_rows > .1 and nvl(num_rows,0) <> 0 order by 1,2


Tried, tested, and true - analyze

(but not recommended unless you have no choice)


Cost-based optimizer Using analyze

set echo off pages 0 feed off lines 999 trimsp on

spool anaall.sql

{analyze tables and indexes code}

spool off

set echo on timi on feed on

spool anaall

@anaall

spool off

Put the pieces together over the next 3 slides


Cost-based optimizer Using analyze on non-partitioned tables

select 'analyze table '||owner||'.'||table_name||

' estimate statistics for table sample '||

'20 percent;'

from sys.dba_tables


and partitioned = 'NO'

order by owner,table_name;


Cost-based optimizer Using analyze on non-partitioned indexes

select 'analyze index '||owner||'.'||

index_name||

' compute statistics;'

from sys.dba_indexes


and partitioned = 'NO'

order by owner,index_name;


Cost-based optimizer Using analyze on partitioned tables

select 'analyze table '||table_owner||'.'||

'.'||table_name||

' partition ('||partition_name||')'||

' estimate statistics sample 2 percent;'

from sys.dba_tab_partitions

where table_owner not in ('SYS','SYSTEM')

order by table_owner,table_name,partition_name;


Cost-based optimizer Using analyze on partitioned indexes

select 'analyze index '||index_owner||

'.'||index_name||

' partition ('||partition_name||')'||

' compute statistics;'

from sys.dba_ind_partitions

where index_owner not in ('SYS','SYSTEM')

order by index_owner,index_name,partition_name;


Not interfering with replication


Cost-based optimizer Exclusions with snapshots

and (owner,table_name) not in (select distinct log_owner,master from sys.dba_snapshot_logs union select log_owner,log_table from sys.dba_snapshot_logs)

and (owner,index_name) not in (select a.owner,a.index_name from sys.dba_indexes a, sys.dba_snapshot_logs b where a.table_name = b.master)

Dark side of the moon


• Analyzing collides with snapshot refreshes

• Restrictive lock inhibits job execution

• System load can skyrocket

• Horrific latch contention

6:57pm up 6 day(s), 7:12, 9 users, load average: 1.06, 1.08, 1.10

4:13am up 8 day(s), 7:12, 9 users, load average: 341.06, 309.08, 301.10

normalduring analyze

Cost-based optimizer Exclusions with snapshots


Stuff just too big to analyze


• DBA nightmare

• exclude based on row count

• gather stale takes care of most very big tables

• if still required– store large table names somwhere– join with dba_tables when building calls to

DBMS_STATS

Cost-based optimizer Exclusions – large objects


Cost-based optimizer Implementation without study

Stab

le e

nviro

nmen

t

Hastily implemented

collection plan

X-DBA

Eehah!


• Know your options

• Adopt an approach

• Liaise with consumer

• No cowboy implementation

• Staleness of statistics

Cost-based optimizerBest practices

• The whole schema• Ensure new objects are

analyzed– Whose responsibility

– Step in promotion of code and dependent objects

• ONLY option


Application tuning



Allow everyone to EXPLAIN

themselves


Application tuning plustrce role

• Create at once when setting up a new instance or inheriting an old one

• plustrce.sql as SYS from ?/sqlplus/admin

• PLAN_TABLE beforehand using ?/rdbms/admin/utlxplan

• There's nothing to hide• Access to dynamic

performance tables used for – v_$sessstat

– v_$statname

– v_$session

• Give access to all


AUTOTRACE and beyond


• Want to write good code

• Arm them with the tools

• Imbed testing into coding – education fosters growth

Application tuning Empowering the developers

set autot trace exp

SP2-0613: Unable to verify PLAN_TABLE format or existence

SP2-0611: Error enabling EXPLAIN report

• Centrally managed PLAN_TABLE with public or private synonyms


Application tuning Foster smart coding habits

SQL> set autot trace exp

SQL> select * from mailing partition (mailing_p04);

Execution Plan

----------------------------------------------------------

0 SELECT STATEMENT Optimizer=CHOOSE (Cost=1 Card=164 Bytes=337676)

1 0 TABLE ACCESS (FULL) OF 'MAILING' (Cost=1 Card=164 Bytes=337676)

SQL> select * from mailing;

Execution Plan

----------------------------------------------------------

0 SELECT STATEMENT Optimizer=CHOOSE (Cost=2 Card=984 Bytes=2026056)

1 0 PARTITION RANGE (ALL)

2 1 TABLE ACCESS (FULL) OF 'MAILING' (Cost=2 Card=984 Bytes=2026056)


Understanding the cost


Application tuning Cost analysis

set echo off term off feed off ver off

select decode(id,0,'',

lpad(' ',2*(level-1))||level||'.'||position)||' '||

operation||' '||options||' '||object_name||' '||

object_type||' '||

decode(id,0,'Cost = '||position) Query_plan

from plan_table

connect by prior id = parent_id

and statement_id = upper('&1')

start with id = 0 and statement_id = upper('&1');


Application tuning Listen and listen closely

You can only compare costs between different wordings of the same SQL statement NOT across statements.

You won't get away with it!


Find potentially problematic SQL statements before it's too late


Application tuning Buffer gets measurement

select buffer_gets,sql_text,executions,

buffer_gets/executions

from v$sqlarea

where buffer_gets > 200000

and v$sqlarea.executions != 0

order by buffer_gets/executions desc

Good place to start


Assess I/O balance while applications interact with instance


col file_name form a30 head File

col tablespace_name form a20 head Tbsp

col a new_value preads

col c new_value pwrites

select sum(phyrds) a,sum(phywrts) c

from v$filestat;

select file_name,tablespace_name,

phyrds/&b*100 pctrd,phywrts/&d*100 pctwrt

from sys.dba_data_files ddf,v$filestat vf

where ddf.file_id = vf.file#

and (phyrds/&preads*100 > 5 or phywrts/&pwrites*100 > 5)

order by 3;

Application tuning I/O balance - primer

/u04

/u02


• Share the responsibility

• Make inroads with management

• Balanced I/O patterns

• Arm the developers so they can help themselves

Application tuningBest practices

• Compare relative costs within different wordings of the same statement

• Imbed in program development

• Pick reasonable measurement indicators


Working with OSS



• The first place to start

• Be smart with your search criteria

• Save yourself and OSS time

• Someone else's problem yesterday is yours today

• Learn from others' experience

Working with OSS MetaLink

Me too!


• Use profiles– 10 per account– keep them up-to-date– organize in 1 central account

• Familiarize yourself with updates– current O/S? uname –a– current Oracle version tool herald

Working with OSS Be a smart DBA


Arm yourself with the necessary backup to your

request


Working with OSS Profiles

Organize by client and O/S


Working with OSS Be specific

Problem with rman

Oracle error when doing a

list backup command

Unique constraint

violation when trying to list

backup


• Keyword scan of free form entry

• Routed to subject experts

• Response time – 30-60 minutes– Severity 1 next to immediate

• Preferred contact method is email– ensure OSS has correct address– check incoming mail regularily

Working with OSS TAR intake

Be smartBe smartBe smartBe smartBe smartBe smartBe smart


Working with OSS Tools of the trade

lert log

ode racle error(s)

race file(s)xplain plan

init.ora


• Have realistic expectations

• Do your homework first (MetaLink)

• Correct contact information

• Be prepared

Working with OSSBest practices

• Use email—best communications performance

• Respond to requests• No games


Working with OSS


Hodge-podge



Hodge-podge Admin scripts

• ?/rdbms/admin

• Familiarize yourself with the contents of this directory in your spare timespare time

• Two part naming convention– dbmsabcd.sql– prvtabcd.plb


Hodge-podge Hard-core education

Just what do you think you're doing Dave?


Hodge-podge Smart professionals

$$$$


Hodge-podge In a bind

• Work with your developers to bind everything– perl– SQL*Plus– AOWBI

• Re-usable SQL• Computation of hash

value very restrictive

select sql_text,count(*) from v$sqlarea where instr(sql_text,'":SY"') > 0 group by sql_text;

select count(*) from v$sqlarea;

select count(*) from v$sqlarea where sql_text like '%'||''''||'%';


Hodge-podge Index foreign keys

• Development requires primary/foreign key relationships to protect data integrity

• Primary key constraints using index• Never think of or take the time to

index foreign key columns• Locks on deleting from parent

col table_name form a20 head Tablecol column_name form a30 heading 'Missing index for FK'

primary key

foreign key

index

INDEX

HUGE locking problems

oops!


select dc.table_name,dcc.column_name from sys.dba_constraints dc, sys.dba_cons_columns dcc where dc.constraint_type = 'R' and dc.constraint_name = dcc.constraint_name and dc.owner not in ('SYS','SYSTEM') and not exists (select ' ' from sys.dba_indexes di,sys.dba_ind_columns dic where di.index_name = dic.index_name and di.table_name = dc.table_name and dic.column_name = dcc.column_name);

Hodge-podge Finding non-indexed foreign keys


• Frustrating venture• Endless Oracle errors• Protection as well as integrity

• constraint_type – C for check

– R for reference

– P for primary

• r_constraint_name• r_owner

Hodge-podge Manage RI before it manages you


Hodge-podge Manage RI before it manages you

SYS_SYS_alter table … add constraint …_pk primary key (…) using index storage (initial N next N pctincrease 0) tablespace …;

alter table … add constraint …_fk foreign key (…) references … (…);

Thou shalt name your constraints

Thou shalt alter table … add constraint


Hodge-podge Saving foreign key constraints – part 1

select 'alter table '||uc1.owner||'.'||uc1.table_name|| chr(10)||' drop constraint '|| uc1.constraint_name||';' from user_constraints uc1, -- foreign key constraint def user_constraints uc2, -- primary key constraint def user_cons_columns ucc1, -- columns in foreign key user_cons_columns ucc2 -- columns in primary key where uc1.r_constraint_name = upper(uc2.constraint_name) and ucc2.constraint_name = upper(uc2.constraint_name) and ucc1.constraint_name = uc1.constraint_name and uc2.table_name in ({list_of_tables});

DBAs worth their weight in goldDBAs worth their weight in gold


select 'alter table '||uc1.owner||'.'||uc1.table_name|| ' add constraint '||chr(10)||' '|| uc1.constraint_name||chr(10)||' foreign key ('|| ucc1.column_name||')'|| ' references '||uc2.owner||'.'||uc2.table_name|| ' ('||ucc2.column_name||');' from user_constraints uc1, -- foreign key constraint def user_constraints uc2, -- primary key constraint def user_cons_columns ucc1, -- columns in foreign key user_cons_columns ucc2 -- columns in primary key where uc1.r_constraint_name = upper(uc2.constraint_name) and ucc2.constraint_name = upper(uc2.constraint_name) and ucc1.constraint_name = uc1.constraint_name and uc1.table_name in ({list_of_tables});

Hodge-podge Saving foreign key constraints – part 2


Hodge-podge Extract source code – procedures / functions

set lines 9999 trimsp on pages 0 echo off feed off ver off sqlbl onspool pfselect decode(line,1,'create or replace '||text,text) from user_source where name = upper('&1') order by line;prompt /spool off

• Be prepared / be smart• Quicker and more useful than

alter procedure GEO_MAINT compile;sho errors package geo_maint


Hodge-podge Extract source code - packages

set lines 9999 trimsp on pages 0 echo off feed off ver off sqlbl onspool pkgselect decode(line,1,'create or replace '||text,text) from user_source where name = upper('&1') and type = 'PACKAGE' order by line;prompt /promptselect decode(line,1,'create or replace '||text,text) from user_source where name = upper('&1') and type = 'PACKAGE BODY' order by line;prompt /spool off


• Do not have the same partition implementation as their data

• Boundaries specified on creation

• Must be rebuilt from scratch when performing partition maintenance– adding or dropping– splitting or merging

Hodge-podge Global partitioned indexes


• List or range partitioning

• Painstakingly adopted naming convention

• Date or surrogate key based approach easiest to work with

• Ensure there are no rows in last 2 partitions

Hodge-podge Avoid global index rebuilds


• Partition naming - table– table name + highest possible date– e.g., SUBS_20020831

• format of date mask important

• allows for pseudo-sequential queries

• Partition naming – index– table name + index name + U/N/F identifier– unique / non-unique / function-based


it's 3AM – your planning will

pay off



set pages 0 lines 999 trimsp on ver off echo off

col a new_value mxname

select max(partition_name) a from dba_tab_partitions where table_owner = upper('&1') and table_name = upper('&2');

select 'Partitioned table '||upper('&1')||'.'|| upper('&2')||' has '||count(*)|| ' rows in last partition ('||'&mxname'||')' from &1..&2 partition (&mxname) having count(*) = 0;

set lines 75


set echo off feed off pages 0select distinct '@lp_look '||table_owner|| ' '||table_name from sys.dba_tab_partitions order by table_owner,table_name;. . . SQL> @lp_look TERA WORKSQL> @lp_look TERA YIELD. . .Partitioned table TERA.WORK has 3 rows in last partition (TERA_WORK_P20030630)Partitioned table TERA.YIELD has 8 rows in last partition (TERA_YIELD_P20030831)



Hodge-podge Shutdown abort

When running with or without media recovery enabled

SQL> shutdown abortORACLE instance shutdown.SQL> startup restrict. . .SQL> shutdown. . .ORACLE instance shutdown.

No jobs submitted in

restricted mode


Hodge-podge A word on OEM


Hodge-podge Weaning yourself of Server Manager

• No more svrmgrl with release 9i• No more internal user• Done exclusively in SQL*Plus,

unlike 8i with either/or• Close the one remaining

inconsistency between the way these 2 tools behave

• Ripple affect on backup scripts

9i


Hodge-podge Ensuring tools behave exactly the same way

SVRMGR> select count(*), cus_id

2> from reader

3>

4> group by cus_id

5> having count(*) > 1;

SQL> select count(*), cus_id

2> from reader

3>

SQL>

• Server Manager tolerates

blank lines, whereas

SQL*Plus didn't until set sqlbl on

>= 8i


Hodge-podge Change in logon procedures

connect internal

/nologconnect / as sysdba

8i

9i10g


Hodge-podge Online redo log maintenance

• To protect you from yourself, rename the members …

select group#,member from v$logfileorder by group#,memberGROUP# MEMBER------ ----------------------- 1 /redo1/beg9/redo01a.log 1 /redo2/beg9/redo01b.log 2 /redo2/beg9/redo02a.log 2 /redo1/beg9/redo02b.log

Before … After …select group#,member from v$logfileorder by group#,memberGROUP# MEMBER------ ----------------------- 1 /redo1/beg9/log1_g1.log 1 /redo2/beg9/log2_g1.log 2 /redo2/beg9/log1_g2.log 2 /redo1/beg9/log2_g2.log


practices allow your systems to better.

Better systems = users.

The chicken or the egg??

users contribute to a smarter DBA

who

ha

ve

are able

to

and become


DBA Best Practices

Oracle DBA Best Practices

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