apex schem a

8/12/2019 Apex Schem A

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Oracle Application ExpressSchema Design Guidelines

Presenter: Flavio Casetta, Yoco a!com


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a"out me

Flavio Casetta Founder o# Yoco a!com Editor o# "log Oracle$uir%s!"logspot!com &'( ears in the )* + ( ears developing applications on Oracle +'( ears developing data"ase applications apex developer since htmld" +!'


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June 24, 2009 Flavio Casetta - www.yocoya.com 4

goals


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goals the goals o# ever apex developer should "e

to "uild #ast, scala"le applications that areeas to use, deplo and maintain

to avoid reinventing the .heelto avoid .riting the same code over and overagain

the aim o# this presentation is to stress theimportance o# proper data"ase design as astrong #oundation #or our apex applications


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d" o"-ects mapping to apex components


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mapping


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ta"les, vie.s, indexes


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ta"les, vie.s, indexes apex2s ta"le "uilder .i1ard creates onl heap

ta"les


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ta"les, vie.s, indexes S$3 Developer2s ta"le "uilder instead comes

.ith advanced options


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heap ta"les are "est #or data that gro.s overtime! *he developer must properl designindexes #or improving data access!

.hen evaluating the indexes to "e created,consider that an column4s5 declared as #oreign%e 4s5 should "e indexed in order to avoidcontention

i# using oracle EE, consider using "itmap indexes#or columns containing #e. distinct values onlarge ta"les .ith lo. transactional activit 4li%e#act ta"les in a D65


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ta"les, vie.s, indexes )O*s are "est #or ta"les accessed " primar %e

and .ith lo. transactional activit ! o#ten reports and page items need to displa a

description starting #rom a #oreign %e value4.hich is the primar %e o# the )O*5 unli%e ordinar indexes, the primar %e o# an

)O* cannot "e re"uilt online


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cluster ta"les come in t.o #orms: index clusters hash clusters

clusters improve )7O " storing data together cluster ta"les 8pre9-oin ta"les index clusters re;uire t.o logical reads

hash clusters re;uire one logical read hash clusters are "est #or ver static data hash clusters need precise si1ing in#ormation


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ta"les, vie.s, indexes external ta"les are use#ul .hen importing data

#rom texts #ile stored in a director on the samedata"ase server

i# deplo ing an application on a multi9tenanthosting server, ou might have no access to local#olders

#inding the right #ormat #or an external ta"le can"e challenging! Certain com"inations o#parameters ma introduce erratic "ehavior


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ta"les, vie.s, indexes temporar ta"les are good #or volatile data! *here

are t.o t pes o# G**s and the di##er in scope: transaction 4on commit delete ro.s5 oracle session 4on commit preserve ro.s5

given the nature o# apex architecture, usage o#temporar ta"les is limited to operations that"egin and end .ithin the same transaction

practical uses: reporting on data returned " aprocedure


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ta"les, vie.s, indexes vie.s are meant to simpli# the .or% o# a

developer " : hiding complex expressions or -oins that .ould

ma%e a ;uer di##icult to deal .ith en#orcing data access rules, i!e! to limit the

results to data relevant to a certain user

decoding values to human understanda"lelanguage


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ta"les, vie.s, indexes in apex, vie.s are great #or:

reporting 4user de#ined vie.s5 chec%ing apex metadata 4APE


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per#ormance tools #or anal 1ing the per#ormance o# an

apex page: monitor activit reports apex page de"ug mode explain plan trace #iles 0 *BP?OF


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per#ormance onitor activit report

Page @ie.s " 6eighted Page Per#ormance Page @ie.s " Application and Page


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per#ormance

page vie.s " .eighted page per#ormance


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per#ormance

apex page de"ug mode: turn on de"ug " clic%ing on the 8de"ug lin% in

the developer2s tool"ar o# apex 4restrictions

appl 5

enter de"ug mode " adding YES as #i#thparameter in the apex >?3

http:77localhost: 7apex7#/p +& ':+: ::YES

in all cases de"ug mode must "e ena"led
http://localhost:8080/apex/f?p=12345:1:0::YEShttp://localhost:8080/apex/f?p=12345:1:0::YES


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per#ormance inspect de"ug output and spot elapsed

time anomalies


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per#ormance the most li%el candidates #or "ig dela s in

page rendering are non9optimi1ed ;ueries


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per#ormance the next step is to chec% .hat2s .rong .ith

the ;uer " using explain plan statistics must "e up9to9date


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per#ormance the #ull ta"le scan indicates that .e are missing

an index as the ;uer re#erences three columns, the most

e##ective index .ill contain those three columns the order o# the columns in the index is important the anal s s is carried out entirel using apex

#eatures


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per#ormance A#ter creating the index, the cost has

decreased dramaticall


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per#ormance this is con#irmed " the time elapsed

recorded in the de"ug output


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per#ormance additional considerations a"out the index:

i created a compressed index, consuming#e.er "loc%s

the ta"le is + H static, so i set PC*F?EE ,saving even more "loc%s

*he di##erence in the num"er o# "loc%s"et.een the index created .ith de#aultparameters and its 8extreme version is do.nH


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per#ormance

index options comparison


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per#ormance explain plan o# the ;uer on single ta"le

hash cluster


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per#ormance

.hat .as the di##erence the da a#ter/


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per#ormance .hen the previousl mentioned techni;ues are

not enough, tracing can "e ena"led instrumenting the code in the right .a can "e a

li#e sa#er i# properl designed, code instrumentation can "e

ena"led selectivel , .ith minimal impact .hen itis not in use and .ithout collecting unnecessarin#ormation


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per#ormance ena"ling oracle tracing is eas :

http:77localhost: 7apex7#/p +& ':+: 0P=*?ACE YES tracing ma%es sense onl i# ou have access to

#olders on the data"ase server 4on a multi9tenanthosting service this t pe o# action might have"een restricted " the DIA5
http://localhost:8080/apex/f?p=12345:1:0&P_TRACE=YEShttp://localhost:8080/apex/f?p=12345:1:0&P_TRACE=YES


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per#ormance depending on apex2s con#iguration 4either using

em"edded P37S$3 gate.a as Oracle


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per#ormance in order to spot the relevant S$3 statements

;uic%l , ou can em"ed comments containingcustom identi#iers:

select 7K m =app 3O@=E P K7 emp=name d, emp=id r#rom emplo ees

update order=items7K m =app m =page=num process x 1 K7

set ;t :P '=$*Y.here order=id :P '=O?DE?=)D


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P37S$3 and apex


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pl7s;l apex ma%e2s possi"le to .rite an application

.ithout entering a single line o# P37S$3 Functionalities that don2t come o##9the9shel# ma

re;uire a little or a lot o# custom P37S$3 *he developer must "e a.are o# pros and cons

.hen adopting a method #or executing P37S$3


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pl7s;l P37S$3 can "e used in man places

Processes 0 Computations @alidations 0 conditions Post calculation, item source 0 initiali1ation ?eport ;ueries 0 report headings D namic 3O@s P37S$3 regions Authentication #unctions 0 authori1ation schemes Shortcuts Supporting O"-ects


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pl7s;l Given the potential u"i;uit o# P37S$3 inside

apex components, the developer must chooseho. to handle this source code:

as anon mous "loc%s as standalone procedures or #unctions as pac%aged procedures or #unctions


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pl7s;l anon mous "loc%s are the most straight#or.ard

method to execute pl7s;l more di##icult to maintain or %eep trac% o# in case o# an exception the source is exposed source code cannot "e o"#uscated edita"le onl inside apex


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pl7s;l reusa"le procedures and #unctions are the "est

candidates #or inclusion in pac%ages: logging procedures "lac% list #iltering general purpose utilities 4the s.iss9%ni#e o#

each developer5

page #ormatting utilities li%e J*F7J*P #ordi##erent .e" languages


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snapshots or cached reports/


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snapshots or cache snapshots a%a materiali1ed vie.s can save

considera"le resources the can "e com"ined .ith cached report regions

to achieve top per#ormance snapshots come in hand .hen:

ou need to ;uer a column resulting #rom a

com"ination o# multiple columns ou need to ;uic%l return aggregated results

4sums, averages, etc!5


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snapshots or cache

.eighted page per#ormance 4 .%s5


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snapshots or cache

.eighted page per#ormance 4& .%s5


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snapshots or cache the signi#icant di##erence .as achieved "

removing a cached region #rom page 1ero caching is not supported in page 1ero 4a #act not

mentioned in the manual or help, "ut mentionedin the output log in page de"ug mode 5 .ithout snapshots, upon expiration o# the region

cache, page rendering .ill incur in a signi#icantincrease o# response time

this occurrence can "e eliminated " creating asnapshot updated in "ac%ground


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s non ms and d" lin%s

the main reason #or using s non ms is to ma%etransparent to the application .here the datacome #rom

a s non m can point to an o"-ect: in the same schema in another schema in a remote data"ase 4through a d"9lin%5

the t pe o# target o"-ect can "e decided duringthe installation #or instance


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s non ms and d" lin%s

developing an application "asing on s non mscan "e tric% apex does not list pu"lic s non ms in .i1ards

it can "e more productive to develop using localo"-ects that are later replaced " correspondings non ms

t pical situations are #orms on ta"les, ta"ular#orms and the ;uer "uilder


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s non ms and d" lin%s another t pical usage #or pu"lic s non ms in

apex is to ma%e procedures calla"le "anon mous users #rom the >?3

creating a pu"lic s non m #or ?PC calls

simpli#ies the >?3 s ntax: ...!acme!com7!!!7user!pac%age!procedure/arg+ !!! ...!acme!com7!!!7s non m/arg+ !!!

#or securit reasons the s non m must also "e8registered in procedure..v=#lo.=epg=include=mod=local


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