use explain

7/23/2019 Use Explain

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Use EXPLAIN PLAN andTKPROF To Tune Your

ApplicationsRoger Schrag

Database Specialists, Inc.

www.dbspecialists.com


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Todays Session

EXPLAIN PLAN overview

TKPROF overview

Why??? Reading execution !an"

Reading TKPROF reort"


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!ite Paper

Twenty one age" o# detai!" I can$t o""i%!y

cover in a one hour re"entation&

Lot" o# "a'!e code( execution !an"( and

TKPROF reort" that you wi!! "ee are ro%a%!ynot reada%!e when I ut the' u on PowerPoint

"!ide")%ut they are reada%!e in the white aer*

+own!oad, www*d%"ecia!i"t"*co'-re"entation"


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E"ecution Plans and

EXPLAIN PLAN An execution planis a list of steps that Oracle will

follow in order to execute a SQL statement. achstep is one of a finite number of basic operations

!nown to the database ser"er. "en the mostcomplex SQL statement can be bro!en down into aseries of basic operations.

#$LAI% $LA%is a statement that allows &ou to

ha"e Oracle generate the execution plan for an&SQL statement without actuall& executing it. 'ouwill be able to examine the execution plan b&(uer&ing the plan table.


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T!e Plan Ta#le

A!an ta%!eho!d" execution !an" generated

%y the EXPLAIN PLAN "tate'ent*

The typical name for a plan tableis plan_table, but you may use any

name you wish.

Create the plan table by runningutlxplan.sql, located in

$ORACLE_HOME/rdbms/admin.


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I$portant %olu$ns

in t!e Plan Ta#le"tate'ent.id /ni0ue identi#ier #or each execution !an

ti'e"ta' When the execution !an wa" generated

oeration The oeration er#or'ed in one "te o# the execution!an( "uch a" 1ta%!e acce""2

otion"Additiona! in#or'ation a%out the oeration( "uch a" 1%yindex ROWI+2

o%3ect.na'e Na'e o# ta%!e( index( view( etc* acce""ed

oti'i4er Oti'i4er goa! u"ed when creating execution !anid 5te nu'%er in execution !an

arent.id 5te nu'%er o# arent "te


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EXPLAIN PLANPrere&uisites

IN5ERT rivi!ege on a !an ta%!e

A!! nece""ary rivi!ege" to execute the

"tate'ent %eing ex!ained 5ELE6T rivi!ege" on under!ying ta%!e" o#

view"( i# the "tate'ent %eing ex!ained

invo!ve" view"


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EXPLAIN PLAN Synta"

EXPLAIN PLAN

[SET STATEMENT_ID = ]

[INTO &


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'ueryin( an E"ecution

Plan )ro$ t!e Plan Ta#le )se a *O%%*+ ' clause to trace the hierarch&

)se L$AD function to indent rows, ma!ing the

hierarch& easier to follow

$ut statement-id in /R clause to retrie"e onl&

one execution plan at a time

Sample script on next slide shows the most

important information

'ou can also tr& utlxpls.s(l or utlxplp.s(l in

0ORA*L-/O12rdbms2admin


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A Si$ple 'uery to *isplay

E"ecution PlansSET 'E$I#( O##

A))EPT st"t_i* )+A$ P$OMPT ,Enter stte"ent_i*- ,)OL i* #O$MAT ...)OL prent_i* #O$MAT ... +EADIN/ ,PA$ENT,)OL opertion #O$MAT 01 T$2N)ATE)OL o!3e4t_n"e #O$MAT 05SELE)T i*6 prent_i*6 LPAD 78 86 LE'EL 9 :; opertion 8 8 options opertion6 o!3e4t_n"e

#$OM pln_t!le+E$E stte"ent_i* = 8st"t_i*8STA$T IT+ i* = 5

AND stte"ent_i* = 8st"t_i*8)ONNE)T ?( P$IO$ i* = prent_i*

AND stte"ent_i* = 8st"t_i*8&


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A Sa$ple E"ecution PlanS%L> EXPLAIN PLAN SET stte"ent_i* = 8*e"o8 #O$ @ SELE)T 4usto"er_n"e6 4usto"er_nu"!er6 !inBoi4e_nu"!er60 !inBoi4e_tCpe6 !inBoi4e_*te6 !totl_"ount6 4line_nu"!er6 4prt_nu"!er6 4quntitC6 4unit_4ost

1 #$OM 4usto"ers 6 inBoi4es !6 inBoi4e_ite"s 4 +E$E 4inBoi4e_i* = -!: F AND 4line_nu"!er = -!@ G AND !inBoi4e_i* = 4inBoi4e_i* . AND 4usto"er_i* = !4usto"er_i*&EHpline*S%L> eHplinsqlEnter stte"ent_i*- *e"o ID PA$ENT OPE$ATION O?JE)T_NAME9999 999999 99999999999999999999999999999999999 99999999999999999 5 SELE)T STATEMENT : 5 NESTED LOOPS

@ : NESTED LOOPS 0 @ TA?LE A))ESS ?( INDEX $OID IN'OI)E_ITEMS 0 INDEX 2NI%2E S)AN IN'OI)E_ITEMS_PK 1 @ TA?LE A))ESS ?( INDEX $OID IN'OI)ES 1 INDEX 2NI%2E S)AN IN'OI)ES_PK F : TA?LE A))ESS ?( INDEX $OID )2STOME$S G F INDEX 2NI%2E S)AN )2STOME$S_PK


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Ot!er ays to

+ie, E"ecution Plans The autotrace #eature in 57L8P!u"

Per#or'ance tuning too!"

6hec9 out TOA+ #ro' 7ue"t 5o#tware at,

htt,--www*toad"o#t*co'-down!d*ht'!

SET A2TOT$A)E O##ONT$A)EONL( [EXPLAIN] [STATISTI)S]


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Sa$ple Autotrace

Output in S'L-PlusEHe4ution Pln9999999999999999999999999999999999999999999999999999999999 5 SELE)T STATEMENT Opti"ier=)+OOSE 7)ost= )r*=: ?Ctes=0.; : 5 NESTED LOOPS 7)ost= )r*=: ?Ctes=0.; @ : NESTED LOOPS 7)ost=0 )r*=: ?Ctes=@F;

0 @ TA?LE A))ESS 7?( INDEX $OID; O# 8IN'OI)E_ITEMS8 7)ost =@ )r*=: ?Ctes=:1; 0 INDEX 72NI%2E S)AN; O# 8IN'OI)E_ITEMS_PK8 72NI%2E; 7 )ost=: )r*=@; 1 @ TA?LE A))ESS 7?( INDEX $OID; O# 8IN'OI)ES8 7)ost=: ) r*=@ ?Ctes=@; 1 INDEX 72NI%2E S)AN; O# 8IN'OI)ES_PK8 72NI%2E; F : TA?LE A))ESS 7?( INDEX $OID; O# 8)2STOME$S8 7)ost=: )r *=:55 ?Ctes=:@55; G F INDEX 72NI%2E S)AN; O# 8)2STOME$S_PK8 72NI%2E;


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Sa$ple Plan *isplay inTOA*


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EXPLAIN PLAN

Li$itations +he #$LAI% $LA% statement pro"ides a good faithestimate of the execution plan that Oracle would use.

+he real plan that gets used ma& differ from what

#$LAI% $LA% tells &ou for man& reasons3

: Optimi4er stats, cursor sharing,, bind "ariable pee!ing,

d&namic instance parameters ma!e plans less stable.

: #$LAI% $LA% does not pee! at bind "ariables.

: #$LAI% $LA% does not chec! the librar& cache to see if

the statement has alread& been parsed.

#$LAI% $LA% does not wor! for some (ueries3

O$A9@@.51- 4nnot 44ess ros ro" non9neste* t!le ite"


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+ie,in( Actual E"ecution

Plans +he "0s(l "iew shows statements in the librar& cache. /ere &ou can

find the address, hash "alue, and child number for a statement of

interest.

+he "0s(l-plan "iew shows the actual execution plan for each

statement, gi"en its address, hash "alue, and child number. +he

columns are similar to the plan table.

+he "0s(l-plan-statistics "iew shows actual statistics 5rows, buffer

gets, elapsed time, etc.6 for each operation of the execution plan.

+he "0s(l-plan and "0s(l-plan-statistics "iews are a"ailable starting

in Oracle 7i. "0s(l-plan-statistics is not populated b& default.


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A Si$ple 'uery to *isplay

Actual E"ecution PlansSET 'E$I#( O##)OL i* #O$MAT ...)OL prent_i* #O$MAT ... +EADIN/ ,PA$ENT,)OL opertion #O$MAT 01 T$2N)ATE

)OL o!3e4t_n"e #O$MAT 05SELE)T i*6 prent_i*6 LPAD 78 86 LE'EL 9 :;

opertion 8 8 options opertion6 o!3e4t_n"e#$OM 7 SELE)T i*6 prent_i*6 opertion6 options6 o!3e4t_n"e #$OM Bsql_pln

+E$E **ress = 8**ress8 AND s_Blue = s_Blue AND 4il*_nu"!er = 4il*_nu"!er ;STA$T IT+ i* = 5)ONNE)T ?( P$IO$ i* = prent_i*&


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Trace Files and TKPROF +he Oracle ser"er process managing a database session

writes a "erbosetrace filewhen SQL trace is enabled for the

session.

+8$RO9is a utilit& pro"ided b& Oracle that formats SQL

trace files into "er& helpful and readable reports. +8$RO9 isinstalled automaticall& when the database ser"er software is

installed. 'ou in"o!e +8$RO9 from the operating s&stem

command line: there is no graphical interface for +8$RO9.

Starting in Oracle 7i +8$RO9 can read extended SQL tracefiles and report on wait e"ents statistics.


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Ena#lin( S'L Trace

At the instance le"el3

sql_tr4e = true

ti"e*_sttisti4s = true (optional)

In &our own session3ALTE$ SESSION SET sql_tr4e = T$2E&

ALTE$ SESSION SET ti"e*_sttisti4s = T$2E&(optional)

In another session3

S(S*!"s_sCste"set_sql_tr4e_in_session

76 6 T$2E;


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Findin( t!e Trace File

Loo! in the user dump destination. On O9Acompliant s&stems this will be0ORA*L-AS2admin20ORA*L-SID2udump

*hec! timestamps and file contents to seewhich trace file is &ours

If non;DAs need access to trace files, add_tr4e_iles_pu!li4 = trueto the

parameter file to a"oid permissions problemson )nix platforms

)se a dedicated ser"er connection whentracing, if possible.


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For$attin( a Trace File

,it! TKPROFIn"o!e +8$RO9 from the operatings&stem prompt li!e this3

tRpro [eHplin=


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TKPROF %o$$and.line

Ar(u$ents

trace file The SQL trace file to be formattedoutput file The formatted output to be writte b! T"#$%&

e'plai( )ataba*e lo+i to be u*ed if !ou wat the output to

iclude e'ecutio pla*

*!*( %mit ,recur*i-e SQL. performed b! the S/S u*er*ort( Li*t traced SQL *tatemet i the output file i a

*pecific order

tRpro [eHplin=


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TKPROF Sa$ple Output

SELE)T 4usto"er_n"e6 4usto"er_nu"!er6 !inBoi4e_nu"!er6 !inBoi4e_tCpe6 !inBoi4e_*te6 !totl_"ount6 4line_nu"!er6 4prt_nu"!er6 4quntitC6 4unit_4ost#$OM 4usto"ers 6 inBoi4es !6 inBoi4e_ite"s 4

+E$E 4inBoi4e_i* = -!:AND 4line_nu"!er = -!@AND !inBoi4e_i* = 4inBoi4e_i*

AND 4usto"er_i* = !4usto"er_i*

4ll 4ount 4pu elpse* *isR querC 4urrent ros9999999 999999 99999999 9999999999 9999999999 9999999999 9999999999 9999999999Prse : 551 55@ 5 5 5 5EHe4ute : 555 555 5 5 5 5#et4 @ 555 555 G G 5 :9999999 999999 99999999 9999999999 9999999999 9999999999 9999999999 9999999999

totl 551 55@ G G 5 :

Misses in li!rrC 44e *uring prse- :Opti"ier gol- )+OOSEPrsing user i*- 0 7$S)+$A/;


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!y Loo/ at E"ecutionPlans

and TKPROF Reports0

$roacti"el& tune applications that are in de"elopment

Reacti"el& tune production s&stems that are experiencing

performance problems

stimate resource needs or feasibilit& of ad;hoc (ueries

Quantif& resource needs for specific applications

+hese tools are critical to the application tuningprocess, and tuning at the application le"el is necessar&for high performance s&stems. ith #$LAI% $LA%,"0s(l-plan, and +8$RO9, &ou can3


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Readin( E"ecution Plans


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E"ecution Plan E"a$ple12

SELE)T 4usto"er_i*6 4usto"er_n"e#$OM 4usto"ers

+E$E 2PPE$ 74usto"er_n"e; LIKE 8A)MEU8O$DE$ ?( 4usto"er_n"e&

OPE$ATION O?JE)T_NAME999999999999999999999999999999 99999999999999SELE)T STATEMENTSO$T O$DE$ ?(

TA?LE A))ESS #2LL )2STOME$S


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E"ecution PlanOperations

TA?LE A))ESS #2LL

$erform a full table scan of the indicated table and retrie"e

all rows that meet criteria from the /R clause.Input3no subordinate operations.Output3the necessar& columnsfrom the rows meeting all criteria.

SO$T O$DE$ ?(

Sort the input rows for the purpose of satisf&ing an ORDR' clause.Input3the rows to be sorted.Output3the rows insorted order.


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SELE)T 4usto"er_n"e6 !inBoi4e_nu"!er6!inBoi4e_*te

#$OM 4usto"ers 6 inBoi4es !+E$E !inBoi4e_*te > T$2N) 7S(SDATE 9 :;

AND 4usto"er_i* = !4usto"er_i*&

OPE$ATION O?JE)T_NAME999999999999999999999999999999 99999999999999SELE)T STATEMENT

NESTED LOOPS TA?LE A))ESS ?( INDEX $OID IN'OI)ES INDEX $AN/E S)AN IN'OI)ES_DATE TA?LE A))ESS ?( INDEX $OID )2STOME$S INDEX 2NI%2E S)AN )2STOME$S_PK


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INDEX 2NI%2E S)AN

Loo! up a complete !e& in a uni(ue index.Input3usuall&no subordinate operations. 58e& "alues t&picall& come

from the original (uer& or a parent operation.6Output34ero or one ROIDs from the index.

INDEX $AN/E S)AN

Loo! up a !e& in a non;uni(ue index, or an incomplete!e& in a uni(ue index.Input3usuall& no subordinateoperations.Output34ero or more ROIDs from the index.


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TA?LE A))ESS ?( INDEX $OID

Loo! up rows in a table b& their ROIDs.Input3a list ofROIDs to loo! up.Output3the necessar& columns

from the rows with the gi"en ROIDs.

NESTED LOOPS

$erform a >oin between two sets of row data using the

nested loops algorithm.Inputs3two separate sets of rowdata.Output3the results of the >oin.

9or each row Oracle reads from the first input, theoperations that ma!e up the second input are executed

once and matching rows generate output.


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SELE)T 4usto"er_n"e6)O2NT 7DISTIN)T !inBoi4e_i*; open_inBs6

)O2NT 74inBoi4e_i*; open_inB_ite"s#$OM 4usto"ers 6 inBoi4es !6 inBoi4e_ite"s 4+E$E !inBoi4e_sttus = 8OPEN8AND 4usto"er_i* = !4usto"er_i*

AND 4inBoi4e_i* 7V; = !inBoi4e_i*/$O2P ?( 4usto"er_n"e&

OPE$ATION O?JE)T_NAME99999999999999999999999999999999 9999999999999999SELE)T STATEMENTSO$T /$O2P ?(

NESTED LOOPS O2TE$ +AS+ JOIN TA?LE A))ESS ?( INDEX $OID IN'OI)ES INDEX $AN/E S)AN IN'OI)ES_STAT2S TA?LE A))ESS #2LL )2STOME$S INDEX $AN/E S)AN IN'OI)E_ITEMS_PK


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+AS+ JOIN

$erform a >oin between two sets of row data usingthe hash >oin algorithm.Inputs3two separate sets of

row data.Output3the results of the >oin.

Oracle reads all rows from the second input andbuilds a hash structure, before reading each rowfrom the first input one at a time. 9or each row fromthe first input, the hash structure is probed andmatching rows generate output.


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NESTED LOOPS O2TE$

Same as the %S+D LOO$S operation, except

that an outer >oin is performed.

SO$T /$O2P ?(

Same as the SOR+ ORDR ' operation, except

that the rows are sorted and grouped to satisf& a?RO)$ ' clause.


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SELE)T 4usto"er_n"e#$OM 4usto"ers

+E$E EXISTS7SELE)T :

#$OM inBoi4es_Bie !

+E$E !4usto"er_i* = 4usto"er_i* AND nu"!er_o_lines > :55;O$DE$ ?( 4usto"er_n"e&

)$EATE O$ $EPLA)E 'IE inBoi4es_Bie AS

SELE)T inBoi4e_i*6 4usto"er_i*6)O2NT7W; nu"!er_o_lines

#$OM inBoi4es 6 inBoi4e_ite"s !+E$E !inBoi4e_i* = inBoi4e_i*/$O2P ?( inBoi4e_i*6 4usto"er_i*&


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6continued7OPE$ATION O?JE)T_NAME99999999999999999999999999999999999 9999999999999SELE)T STATEMENT

SO$T O$DE$ ?( #ILTE$ TA?LE A))ESS #2LL )2STOME$S 'IE IN'OI)ES_'IE #ILTE$ SO$T /$O2P ?( NESTED LOOPS TA?LE A))ESS ?( INDEX $OID IN'OI)ES INDEX $AN/E S)AN IN'S_)2ST_ID INDEX $AN/E S)AN IN'_ITEMS_PK


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#ILTE$

Read a set of row data and discard some rows basedon "arious criteria. +o determine the criteria,

operations from a second input ma& need to beperformed.Input3rows to be examined and,sometimes, an additional subordinate operation thatmust be performed for each row from the first input in

order to e"aluate criteria.Output3the rows from thefirst input that met the criteria.


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'IE

uild a ph&sical representation of a database

"iew or subset of a database "iew. Input3set ofrow data.Output3set of row data thatimplements the "iew or subset of the "iew.


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Notes on E"ecution Plan

Operations +he optimi4er rewrites sub(ueries as >oins and

merges them into the main (uer& whene"er possible.

If a sub(uer& is completel& independent of the main

(uer& and cannot be merged into the main (uer&, theoptimi4er ma& treat the sub(uer& as a separatestatement and lea"e it out of the execution plan for themain (uer&.

+he optimi4er expands "iew definitions and mergesthem into the main (uer& where"er possible. A @Ioperation will onl& appear in an execution plan whenthe "iew definition could not be merged.


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SELE)T WV $2LE W 4ust_n"e6 !4ont4t_n"e#$OM 4usto"ers 6 4ont4tssles4"e4o" !

+E$E 2PPE$7!4ont4t_n"e; = 2PPE$74ust_n"e;&

EHe4ution Pln

999999999999999999999999999999999999999999999999 5 SELE)T STATEMENT Opti"ier=+INT- $2LE : 5 ME$/E JOIN @ : SO$T 7JOIN; 0 @ $EMOTEW SALESA)ME)OM : SO$T 7JOIN; 1 TA?LE A))ESS 7#2LL; O# 8)2STOME$S8

0 SE$IAL_#$OM_$EMOTE SELE)T ,)ONTA)T_NAME,#$OM ,)ONTA)TS, ,?


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E"ecution Plan

Operations$EMOTE

Submit a SQL statement to a remote database "ia Oracle

%et.Input3t&picall& no subordinate operations.Output3the results of the (uer& from the remote database. %otethat the database lin! used to access the remotedatabase and the actual SQL submitted to the remotedatabase will be accessible from the execution plan.


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E"ecution Plan

OperationsSO$T JOIN

Same as the SOR+ ?RO)$ ' operation, except thatthe input is sorted b& the >oin column or columns inpreparation for a >oin using the merge >oin algorithm.


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E"ecution Plan

OperationsME$/E JOIN

$erform a >oin between two sets of row data using

the merge >oin algorithm.Inputs3two separate setsof row data.Output3the results of the >oin.

Oracle reads rows from both inputs in analternating fashion and merges together matching

rows in order to generate output. +he two inputsare assumed to be sorted on the >oin column orcolumns.


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Su$$ary o) Operations

- TA?LE A))ESS #2LL

- TA?LE A))ESS ?( INDEX $OID

-

INDEX 2NI%2E S)AN- INDEX $AN/E S)AN

-NESTED LOOPS

-NESTED LOOPS O2TE$

- +AS+ JOIN

-ME$/E JOIN

-#ILTE$

-'IE

- $EMOTE

- SO$T O$DE$ ?(

- SO$T /$O2P ?(

-

SO$T JOIN

e ha"e not co"ered all of the execution plan operations,but we ha"e co"ered some of the most common ones3


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Ele$ents o) a TKPROFReport

Report heading

: +8$RO9 "ersion, date run, sort option, trace file

One entr& for each distinct SQL statement in trace file

: Listing of SQL statement

: O*I call statistics3 count of parse, execute, and fetchcalls, rows processed, and time and I2O used

: $arse information3 parsing user, recursi"e depth,librar& cache misses, and optimi4er mode

: Row source operation listing

: xecution plan listing 5optional6

: ait e"ent listing 5optional6

El ) TKPROF


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Ele$ents o) a TKPROFReport

6continued7 Report Summar&

: O*I call statistics totals

: *ounts of how man& statements were found in thetrace file, how man& were distinct, and how man&were explained in the report.


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Sa$ple TKPROF Report

9eadin(TKP$O#- $elese G::5 9 Pro*u4tion on e* Aug . :.-5-0 @555

74; )opCrigt :... Or4le )orportion All rigts reserBe*

Tr4e ile- eH"pletr4Sort options- *eultWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWWW4ount = nu"!er o ti"es O)I pro4e*ure s eHe4ute*4pu = 4pu ti"e in se4on*s eHe4utingelpse* = elpse* ti"e in se4on*s eHe4uting*isR = nu"!er o pCsi4l re*s o !uers ro" *isR

querC = nu"!er o !uers gotten or 4onsistent re*4urrent = nu"!er o !uers gotten in 4urrent "o*e 7usullC or up*te;ros = nu"!er o ros pro4esse* !C te et4 or eHe4ute 4ll


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Sa$ple O%I %all Statistics

SELE)T t!le_n"e#$OM user_t!lesO$DE$ ?( t!le_n"e

4ll 4ount 4pu elpse* *isR querC 4urrent ros9999999 999999 99999999 9999999999 999999999 999999999 999999999 999999999

Prse : 55: 55@ 5 5 5 5EHe4ute : 555 555 5 5 5 5#et4 : 51. 5.. 5 0000 5 :.9999999 999999 99999999 9999999999 999999999 999999999 999999999 999999999totl : 55 :5: 5 0000 5 :.

Misses in li!rrC 44e *uring prse- :Opti"ier gol- )+OOSEPrsing user i*- $S)+$A/ [re4ursiBe *ept- 5]

!at t!e TKPROF Sa$ple


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!at t!e TKPROF Sa$pleon t!e Pre:ious Slide

Tells Us +he application called on Oracle to parse this statementonce while SQL trace was enabled.

+he parse too! .B *$) seconds, .C elapsed seconds.

%o dis! I2Os or buffer gets too! place during the parse,suggesting that no misses in the dictionar& cache.

Oracle was called on to execute this statement once.

+he execution too! under .B *$) seconds.

%o dis! I2Os or buffer gets too! place during the execution.5Queries often defer the wor! to the fetch phase.6

Oracle was called on B times to perform a fetch, and atotal of B7 rows were returned.


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!at t!e TKPROF Sa$ple

Tells Us 6continued7 9etching too! .E7 *$) seconds, .77 elapsed seconds.

9etching re(uired FF,GFF buffer gets in consistent mode,but no ph&sical reads were re(uired.

+he statement was not in the librar& cache 5shared pool6when the parse call came in.

+he cost;based optimi4er and a goal of


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Sa$ple Ro, Source

Operation Listin($os $o Sour4e Opertion9999999 999999999999999999999999999999999999999999999999999 :. SO$T O$DE$ ?( :. NESTED LOOPS :.1 NESTED LOOPS O2TE$ :.1 NESTED LOOPS O2TE$ :.1 NESTED LOOPS ::: TA?LE A))ESS ?( INDEX $OID O?J ::: INDEX $AN/E S)AN 7o!3e4t i* 0; ::00. TA?LE A))ESS )L2STE$ TA? :@1 INDEX 2NI%2E S)AN 7o!3e4t i* 0; 00 INDEX 2NI%2E S)AN 7o!3e4t i* 00;

:.0 TA?LE A))ESS )L2STE$ SE/ 0GF INDEX 2NI%2E S)AN 7o!3e4t i* .; :. TA?LE A))ESS )L2STE$ TS 0GG INDEX 2NI%2E S)AN 7o!3e4t i* F;


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Sa$ple E"ecution Plan

Listin($os EHe4ution Pln9999999 999999999999999999999999999999999999999999999999999 5 SELE)T STATEMENT /OAL- )+OOSE :. SO$T 7O$DE$ ?(; :. NESTED LOOPS :.1 NESTED LOOPS 7O2TE$; :.1 NESTED LOOPS 7O2TE$; :.1 NESTED LOOPS ::: TA?LE A))ESS 7?( INDEX $OID; O# 8O?J8 ::: INDEX 7$AN/E S)AN; O# 8I_O?J@8 72NI%2E; ::00. TA?LE A))ESS 7)L2STE$; O# 8TA?8 :@1 INDEX 72NI%2E S)AN; O# 8I_O?JQ8 7NON92NI%2E; 00 INDEX 72NI%2E S)AN; O# 8I_O?J:8 72NI%2E;

:.0 TA?LE A))ESS 7)L2STE$; O# 8SE/8 0GF INDEX 72NI%2E S)AN; O# 8I_#ILEQ_?LO)KQ8 7NON92NI%2E; :. TA?LE A))ESS 7)L2STE$; O# 8TS8 0GG INDEX 72NI%2E S)AN; O# 8I_TSQ8 7NON92NI%2E;


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Notes A#out TKPROF

E"ecution Plan Listin(s xecution plans are onl& included in +8$RO9 reports if

the explainH parameter is specified when +8$RO9 isin"o!ed

+8$RO9 will create and drop its own plan table if onedoes not alread& exist

+he row counts on each step are actualsnot estimates.+his can be "er& helpful when troubleshooting (ueries

that perform poorl&. hen +8$RO9 runs the #$LAI% $LA% statement for a

(uer&, a different execution plan could be returned thanwas actuall& used in the traced session.


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TKPROF Reports;


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rappin( Up

)se #$LAI% $LA%, (ueries against "0s(l-plan, theautotrace facilit& in SQLK$lus, or ?)I tools to "iewexecution plans.

)se +8$RO9 to format SQL trace files for human

readabilit&. xecution plans and +8$RO9 reports gi"e the DA

and application de"eloper a wealth of information thatcan be used to ma!e applications efficient andperform well.

+he catch3 &ou need to !now how to interpretexecution plans and +8$RO9 reports in order to getan& benefit from them. 'ou also ought to !now whento use #$LAI% $LA% "ersus when to (uer&"0s(l-plan.


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Resources

+own!oad thi" "!ide "how( the acco'anying

white aer( and 'any other u"e#u! re"entation"

at,

www*d%"ecia!i"t"*co'-re"entation"


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%ontact In)or$ationRoger Schrag

+ata%a"e 5ecia!i"t"( Inc*

;5an Franci"co( 6A @>

Te!, >B-;>>CB

E'ai!, r"chragDd%"ecia!i"t"*co'

We%, www*d%"ecia!i"t"*co'

use explain

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