sap hana frequently asked interview questions

8/19/2019 SAP Hana Frequently Asked Interview Questions

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SAP HANA FREQUENTLY ASKED INTERVIEW

QUESTIONS

1.What are the diferent t!e" #$ re!%i&ati#n te&hni'(e")

1.ETL based replication using BODS

2.Trigger based replication using SLT

3.Extractor based data acquisition using DXC

. SD!

*.What i" SLT)

SLT stands "or S#$ Landscape Trans"or%ation &'ic' is a trigger based replication.

SLT replication ser(er is t'e replication tec'nolog) to pass data "ro% source

s)ste% to t'e target s)ste%. T'e source can be eit'er S#$ or non*S#$. Targets)ste% is S#$ +#,# s)ste% &'ic' contains +#,# database.

+.I" it !#""i,%e t# %#ad and re!%i&ate data $r#- #ne "#(r&e ""te- t#

-(%ti!%e taret data,a"e "&he-a" #$ HANA ""te-)

-es. !t is possible "or up to .

/.I" it !#""i,%e t# "!e&i$ the t!e #$ data %#ad and re!%i&ati#n)

-es eit'er in real ti%e or sc'eduled b) ti%e or b) inter(al.

0.What i" #n2(rati#n in SLT) T'e in"or%ation to create t'e connection bet&een t'e source s)ste% SLT

s)ste% and t'e S#$ +#,# s)ste% is speci/ed &it'in t'e SLT s)ste% as a

Con/guration. -ou can de/ne a ne& con/guration in Con/guration 0 onitoring

Das'board transaction LT4.

3.I" there an !re4re'(i"ite ,e$#re &reatin the n2(rati#n and

re!%i&ati#n)

5or t'e S#$ source s)ste%s D!S add*on is installed in SLT replication ser(er.

6ser "or 5C connection 'as t'e role !66C7E$L7EOTE assigned but not DD!C.

5or non*S#$ source s)ste%s D!S add*on is not required and grant a databaseuser su8cient aut'ori9ation "or data replication.

5.What i" #n2(rati#n and 6#nit#rin Da"h,#ard)

!t is an application t'at runs on SLT replication ser(er to speci") con/guration

in"or%ation suc' as source s)ste% target s)ste% and rele(ant connections4 so

t'at data can be replicated. !t can also use it to %onitor t'e replication status

transaction LT4.

Status -ello&: !t %a) occur due to triggers &'ic' are not )et created success"ull).

Status ed: !t %a) occur i" %aster ;ob is aborted %anuall) in transaction S3


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# transaction t'at runs on SLT replication ser(er to speci") ad(anced replication

settings li=e

odi")ing target table structures

Speci")ing per"or%ance opti%i9ation settings

De/ne trans"or%ation rules

9.What i" Laten&)

!t is t'e lengt' o" ti%e to replicate data a table entr)4 "ro% t'e source s)ste% to

t'e target s)ste%.

1:.What i" %#in ta,%e)

# table in t'e source s)ste% t'at records an) c'anges to a table t'at is being

replicated. T'is ensures t'at SLT replication ser(er can replicate t'ese c'anges

to t'e target s)ste%.

11.What are Tran"$#r-ati#n r(%e")# rule speci/ed in t'e #d(anced eplication settings transaction "or source tables

suc' t'at data is trans"or%ed during t'e replication process. Exa%ple )ou can

speci") rule to

Con(ert /elds

5ill e%pt) /elds

S=ip records

1*.What ha!!en" ;hen #( "et4(! a ne; n2(rati#n)

T'e database connection is auto%aticall) created along &it' >6!D and ass

trans"er id T7!D4.

# sc'e%a >6!D ensures t'at con/gurations &it' t'e sa%e sc'e%a na%e can be

created.

T'e ass trans"er !D is used in t'e na%ing o" SLT ;obs and t'e s)ste% can

uniquel) identi") a sc'e%a.

1+.What $a&t#r" in


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10.What are the >#," in8#%8ed in re!%i&ati#n !r#&e"")

1. aster Aob !66C7O,!TO7T7!D4

2. aster Controlling Aob !66C7E$L!C7C,T7T7!D4

3. Data Load Aob DTL7T7D#T#7LO#D7T7!D72digits4

.igration Ob;ect De/nition Aob !66C7DE57!>7OBA72digits4

.#ccess $lan Calculation Aob #CC7$L#,7C#LC7T7!D72digits4

13.What i" the re%ati#n ,et;een the n(-,er #$ data tran"$er >#," in the

n2(rati#n "ettin" and the a8ai%a,%e ?@D ;#r !r#&e""e")

Eac' ;ob occupies 1 B>D &or= processes in SLT replication ser(er. 5or eac'

con/guration t'e para%eter Data Trans"er Aobs restricts t'e %axi%u% nu%ber

o" data load ;ob "or eac' %ass trans"er !D T7!D4.

# %ass trans"er !D requires at least bac=ground ;obs to be a(ailable:

One %aster ;ob

One %aster controller ;ob#t least one data load ;ob

One additional ;ob eit'er "or %igration?access plan calculation?to c'ange

con/guration settings in Con/guration and onitoring Das'boardF.

15.I$ #( "et the !ara-eter Bdata tran"$er >#,"C t# :/ in a n2(rati#n

BSHE6A1C a -a"" tran"$er ID ::1 i" a""ined. Then ;hat >#," "h#(%d

,e in the ""te-)

1 aster ;ob !66C7O,!TO7SC+E#14

1 aster Controller ;ob !66C7E$L7C,T7@@17@@@14

#t %ost parallel ;obs "or T7!D @@1 DTL7T7D#T#7LO#D7@@17@1?G@2?G@3?G@4

$er"or%ance: !" lots o" tables are selected "or load ? replication at t'e sa%e ti%e

it %a) 'appen t'at t'ere are not enoug' bac=ground ;obs a(ailable to start t'e

load procedure "or all tables i%%ediatel). !n t'is case )ou can increase t'e

nu%ber o" initial load ;obs ot'er&ise tables &ill be 'andled sequentiall).

5or tables &it' large (olu%e o" data )ou can use t'e transaction #d(anced

eplication Settings !66C7E$L7CO,T4F to "urt'er opti%i9e t'e load and

replication procedure "or dedicated tables.

17.What ha!!en" a$ter the SLT re!%i&ati#n i" #8er)

T'e SLT replication ser(er creates 1 user roles 2 stored procedures and H

tables.

1 6ser

1 $ri(ilege

oles

E$L!C#T!O, SC+E#7D#T#7$OI

E$L!C#T!O,7SC+E#7$OJE76SE

E$L!C#T!O,7SC+E#76SE7#D!,E$L!C#T!O,7SC+E#7SELECT


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2 Stored procedures

S7>#,T7#CCESS S7EIOKE7#CCESS

H Tables

DD@2L DD@2T S7LO>75!LES S7ESS#>ES S7ODE S7ODE7EXT

S7SC+E#7#$ S7ST#T6S

19.What are the diferent re!%i&ati#n "&enari#")

Load eplicate Stop Suspend and esu%e.

Be"ore )ou select an) application table t'e initial load o" t'e tables DD@2L

DD@2T 0 DD@HL %ust be co%pleted as t'e) contain t'e %etadata in"or%ation.

Load: Starts an initial load o" replication data "ro% t'e source s)ste%. T'e

procedure is a one*ti%e e(ent. #"ter it is co%pleted "urt'er c'anges to t'e

source s)ste% database &ill not be replicated.

5or t'e initial load procedure neit'er database triggers nor logging tables are

created in t'e source s)ste%. De"ault settings use reading t)pe 3 DB7SET>ET4

&it' up to 3 bac=ground ;obs in parallel to load tables in parallel or subsequentl)

into t'e +#,# s)ste%.

eplicate: Co%bines an initial load procedure and t'e subsequent replication

procedure real ti%e or sc'eduled4.

Be"ore t'e initial load procedure &ill start database trigger and related logging

table are created "or eac' table in t'e source s)ste% as &ell as in SLT replicationser(er.

Stop eplication: Stops an) current load or replication process o" a table.

T'e stop "unction &ill re%o(e t'e database trigger and related logging tables

co%pletel). Onl) use t'is "unction i" )ou do &ant to continue a selected table

ot'er&ise )ou %ust initiall) load t'e table again to ensure data consistenc).

Suspend: $auses a table "ro% a running replication. T'e database trigger &ill not

be deleted "ro% t'e source s)ste%. T'e recording o" c'anges &ill continue andrelated in"or%ation is stored in t'e related logging tables in t'e source s)ste%.

!" )ou suspend tables "or a long ti%e t'e si9e o" logging tables %a) increase and

ad;ust t'e table space i" required.

esu%e: estarts t'e application "or a suspended table. T'e pre(ious suspended

replication &ill be resu%ed no ne& initial load required4.

*:.What ha!!en" i$ the re!%i&ati#n i" "("!ended $#r a %#n !eri#d #$

ti-e #r ""te- #(tae #$ SLT #r HANA ""te-) T'e si9e o" t'e logging tables increases.


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*1.H#; t# a8#id (nne&e""ar %#in in$#r-ati#n $r#- ,ein "t#red)

$ause t'e replication b) stopping t'e sc'e%a*related ;obs.

**.Wi%% the ta,%e "ie in SAP HANA data,a"e and in the "#(r&e ""te-

the "a-e),o as +#,# database supports co%pression.

*+.When t# # $#r ta,%e !artiti#nin)

!" t'e table si9e in +#,# database exceeds 2 billion records split t'e table b)

using portioning "eatures b) using #d(anced replication settingsF transaction

!66C7E$L7CO,T tab page !66C7E$L7T#BST>4.

*/.Where d# #( de2ne tran"$#r-ati#n r(%e")

B) using #d(anced replication settingsF transaction !66C7E$L7CO,T tab page

!66C #SS 6LE #$4

*0.Are there an "!e&ia% n"iderati#n" i$ the "#(r&e ""te- i" n#n4SAP

""te-)

T'e concept o" trigger*based replication is actuall) %eant "or S#$ source

s)ste%s. T'e %ain dierences are:

T'ere &ill be a database connection bet&een non*S#$ source and SLT s)ste%

instead o" 5C.

Source %ust 'a(e pri%ar) =e)

Tables DD@2L DD@2T &'ic' contains %etadata are ;ust initiall) loaded but not

replicated. T'e read %odules reside on SLT s)ste%.

Tables &it' database speci/c "or%ats %a) need trans"or%ation rules be"ore t'e)

are replicated.

Onl) S#$ supported databases &it' respecti(e DBSL "or S#$ ,et Jea(er


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data,a"e)

-es t'is is auto%aticall) co(ered b) t'e 5C connection used "or data replication

"ro% t'e S#$ source s)ste%.


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Q(e"ti#n" #n %i-it"

*9. 6ai-(- n(-,er #$ ta,%e" in a "&he-a)

131@


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Opti%i9e t'e code "or Declarati(e and !%perati(e logic

Code generation creates Calculation %odels "or Declarati(e logic and L nodes "or

!%perati(e logic

Co%piled procedure creates Content in t'e database Catalog and in epositor).

/1. What ha!!en" ;hen #( -!i%e the !r#&ed(re)During co%pilation t'e call to t'e procedure is re&ritten "or processing b) t'e

calculation engine.

/*. What ha!!en" ;hen #( ee&(te the !r#&ed(re)

!t binds t'e actual para%eters to t'e calculation %odels generated in t'e

de/nition p'ase.

/+. What are the data t!e" "(!!#rted in SQLS&ri!t)

SLScript allo&s t'e de/nitions o" table t)pes and also supports pri%iti(e data

t)pes suc' as !nteger Deci%alpq4 Iarc'ar Blob Ti%esta%p etc.

//. What i" a ta,%e t!e)

Table t)pes are used to de/ne para%eters "or a procedure t'at represent tabular

results.

Exa%ple:

CE#TE T-$E tt7publis'ers #S T#BLE publis'er !,TE>E na%e I#C+#@4

price DEC!#L cnt !,TE>E4P

CE#TE T-$E tt7)ears #S T#BLE )ear I#C+#4 price DEC!#L cnt

!,TE>E4P

/0. What i" the enera% "nta ("ed in &reatin !r#&ed(re)

CE#TE $OCED6E proc7na%e Qpara%eter7clause4R

QL#,>6#>E langR QSL SEC6!T- %odeR

QE#DS SL D#T# QJ!T+ ES6LT I!EJ (ie&7na%eRR #S

local7scalar7(ariables

BE>!, procedure7code E,D

/3. H#; t# re-!i%e a !r#&ed(re)

#LTE $OCED6E proc7na%e ECO$!LE QJ!T+ $L#,R

/5. an #( "!e&i$ a de$a(%t 8a%(e ;hi%e &reatin !r#&ed(re) I" there

an &hane ;hi%e &a%%in the !r#&ed(re)

CE#TE $OCED6E %)7proc !, $1 !,T

!, $2 !,T DE5#6LT 1

O6T out1 D6-4 #S

BE>!,

out1 SELECT :$1 :$2 #S D6- 5O D6-P

E,DP

J'ile calling t'e procedure &e need to pass U,a%ed $ara%etersU &it' to=en

4. C#LL %)7proc $1 3 out1 V4


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!" )ou &ant to speci") all t'e input /elds t'en call state%ent &ould be:

C#LL %)7proc 3 V4

/7. What i" the !(r!#"e #$ !r#&ed(re a%%... With O8er8ie; #!ti#n)

To &rite t'e results o" a procedure call directl) into a p')sical table.

C#LL %)7proc 3 ,6LL4 J!T+ OIEI!EJP

/9. What i" the !(r!#"e #$ !r#&ed(re a%%.....In De,( 6#de #!ti#n)

!t creates t'e additional debug in"or%ation during t'e execution o" t'e

procedure. T'is t)pe o" call 'as additional runti%e o(er'ead 'ence s'ould be

used "or debugging purposes onl).

C#LL %)7proc 3 ,6LL4 !, DEB6> ODEP

0:. What i" Ta,%e 8aria,%e)

T'ese are (ariables &it' table t)pe &'ic' are bound to t'e (alue o" a p')sical

table SL quer) or a calculation engine plan operator. Table (ariables are boundusing equalit) operator.

01. What i" a "&a%ar 8aria,%e)

Je de/ne scalar (ariable as !, O6T or !,O6T and can be re"erenced an)&'ere

in a procedure.

lt7expensi(e7boo=s SELECT title price crc) 5O :it7boo=s

J+EE price :%in$rice #,D crc) :currenc)P

!n abo(e assign%ent t'e (ariable lt7expensi(e7boo=s is bound. Iariable

:it7boo=s re"ers to an !, para%eter o" a Table t)pe. :%in$rice and :currenc) re"er

to !, para%eter o" a scalar t)pe.

0*. What i" E !%an #!erat#r) What are the diferent &ate#rie")

CE plan operator does t'e data trans"or%ation "unctionalit) internall) and used

in de/nition o" "unctions. !t is an alternate to using SL state%ents.

Data Source #ccess operators t'at bind a colu%n table or a colu%n (ie& to a

table (ariable. CE7COL6,7T#BLE CE7AO!,7I!EJ CE7OL#$7I!EJ

CE7C#LC7I!EJ4

elational operators t'at allo& a user to b)pass t'e SL processor during

e(aluation and directl) executed in t'e calculation engine.

CE7AO!, CE7LE5T7O6TE7AO!, CE7!>+T7O6TE7AO!,CE7$OAECT!O,CE7C#LC CE7#>>E>#T!O, CE76,!O,7#LL4

Special extensions i%ple%ent e.g. crucial business "unctions inside t'e

database =ernel.

CE7IET!C#L76,!O, CE7CO,IES!O,4

0+. What i" EOLU6NTA?LE #!erat#r)

!t pro(ides access to an existing colu%n table. !t ta=es t'e na%e o" t'e table and

returns its content bound to a (ariable.

Exa%ple:ot7boo=s1 CE7COL6,7T#BLE BOOKSF4P


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ot7boo=s2 CE7COL6,7T#BLE BOOKSF QT!TLEF $!CEF CC-FR4P

T'is exa%ple onl) &or=s on a colu%n table and does not in(o=e t'e SL

processor. !t is se%anticall) equi(alent to t'e "ollo&ing:

ot7boo=s3 SELECT N 5O boo=sP

ot7boo=s SELECT title price crc) 5O boo=sP

T'e "unction t'at pro(ide data source access does not allo& rena%ing o"

attributes.

0/. What i" EGOINVIEW #!erat#r)

!t return results "or an existing ;oin (ie& also =no&n as #ttribute (ie&4. !t ta=es

t'e na%e o" ;oin (ie& and optional list o" attributes as para%eters.

Exa%ple:

out CE7AO!,7I!EJ $OD6CT7S#LESF Q$OD6CT7KE-F $OD6CT7TEXTFS#LESFR4P

00. What i" EOLAPVIEW #!erat#r)

!t return results "or an existing OL#$ (ie& also =no&n as #nal)tical (ie&4. !t

ta=es t'e na%e o" OL#$ (ie& and an optional list o" =e) /gures and di%ensions

as para%eters. T'e OL#$ (ie& is grouped b) di%ensions and t'e =e) /gures are

aggregated using t'e de"ault aggregation o" t'e OL#$ (ie&.

Exa%ple:

out CE7OL#$7I!EJ OL#$7(ie&FQDi%1F ="FR4P!s equi(alent to

out SELECT di%1 S6="4 5O OL#$7(ie& >O6$ B- di%1P

03. What i" EALVIEW #!erat#r)

!t returns results "or an existing calculation (ie&. !t ta=es t'e na%e o" t'e

calculation (ie& and optionall) a pro;ection list o" attribute na%es.

Exa%ple:

out CE7C#LC7I!EJ C#LC7(ie&F QC!DF C,#EFR4P

!s equi(alent to out SELECT cid cna%e 5O C#LC7(ie&P

05. What i" EGOIN #!erat#r)

!t calculates a inner ;oin o" t'e gi(en pair o" tables on a list o" ;oin attributes.

Eac' pair o" ;oin attributes %ust 'a(e identical attribute na%es else one o"

t'e% %ust be rena%ed prior to t'e ;oin.

Exa%ple:

ot7pubs7boo=s1 CE7AO!, :lt7pubs :it7boo=s Q$6BL!S+EFR4P

ot7pubs7boo=s2 CE7AO!, :lt7pubs :it7boo=s Q$6BL!S+EFR QT!TLEF ,#EF$6BL!S+EF -E#FR4P


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!s equi(alent to

ot7pubs7boo=s3 SELECT $.publis'er as publis'er na%e street post7code

cit)

countr) isbn title edition )ear price crc)

5O :lt7pubs #S $ :it7boo=s as B J+EE $.publis'er B.publis'erP

ot7pubs7boo=s SELECT title na%e $.publis'er as publis'er )ear

5O :lt7pubs #S $ :it7boo=s #S B

J+EE $.publis'er B.publis'erP

07. What i" ELEFTOUTERGOIN #!erat#r)

!t calculates t'e le"t outer ;oin. Besides t'e "unction na%e t'e s)ntax is sa%e as

CE7AO!,.

09. What i" ERI@HTOUTERGOIN #!erat#r)!t calculates t'e rig't outer ;oin. Besides t'e "unction na%e t'e s)ntax is sa%e

as CE7AO!,.

3:. What i" EPROGETION #!erat#r)

!t restricts t'e colu%ns in t'e table (ariable and optionall) rena%es colu%ns

co%putes expression or applies a /lter.

Exa%ple:

ot7boo=s1 CE7$OAECT!O,:it7boo=s QT!TLEF $!CEF CC-F #S

C6E,C-FR U$!CEF @U4P!s equi(alent to

ot7boo=s2 SELECT title price crc) #S currenc)

5O :it7boo=s J+EE price @P

31. What i" EAL #!erat#r)

!t e(aluates an expression and t'en bound to a ne& colu%n

Exa%ple:

&it'7tax CE7$OAECT!O,:product QC!DF C,#EF O!DF S#LESF

CE7C#LCUFS#LESF N :(at7rateUdeci%al1@244 #S S#LES7I#TFR

UUFC,#EF U:cna%eUUU4P

!s equi(alent to

&it'7tax2 SELECT cid cna%e oid sales sales N :(at7rate #S sales7(at

5O :product

J+EE cna%e U:cna%eUP

#ll colu%ns used in CE7C#LC 'a(e to be included in t'e pro;ection list. #not'er

"requent use o" CE7C#LC is co%puting ro& nu%bers. CE7C#LCUro&nu%4U integer4 #S W#,KW


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3*. What i" EA@@RE@ATION #!erat#r)

!t groups t'e input and co%putes aggregates "or eac' group.

Supported aggregate "unctions are countcolu%nF4 su%colu%nF4

%axcolu%nF4 %incolu%nF4.

6se su%colu%nF4?countcolu%nF4 to co%pute t'e a(erage.

Exa%ple:

ot7boo=s1 CE7#>>E>#T!O,:it7boo=s QCO6,T $6BL!S+EF4 #S C,TR

Q-E#FR4P

!s equi(alent to

ot7boo=s2 SELECT CO6,T publis'er4 as cnt )ear 5O :it7boo=s >O6$ B-

)earP

3+. What i" EUNIONALL #!erat#r)!t co%putes t'e union o" t&o tables &'ic' need to 'a(e identical sc'e%as.

Exa%ple:

ot7all7boo=s1 CE76,!O,7#LL :lt7boo=s :it7audit7boo=s4P

!s equi(alent to

ot7all7boo=s2 SELECT N 5O :lt7boo=s

6,!O, #LL

SELECT N 5O :it7audit7boo=sP

3/. What i" "!e&ia% #!erat#r)CE7IET!C#L76,!O, and CE7CO,IES!O, are t'e special operators &'ic' do

not 'a(e an) i%%ediate SL equi(alent.

30. What #!erat#r i" ("ed t# de,( SQLS&ri!t !r#&ed(re")

T#CE operaor. !t traces t'e tabular data passed as its argu%ent into a local

te%porar) table and return its input un%odi/ed. T'e na%es o" t'e te%porar)

tables can be retrie(ed "ro% t'e S-S.SLSC!$T7T#CE (ie&.

Exa%ple: out T#CE :input4P

33. H#; t# "et4(! tra&in)

5ro% t'e #d%inistration perspecti(e na(igate to tab Trace Con/gurationF . !n

order to c'ange settings )ou need to 'a(e s)ste% pri(ileges T#CE #D!,F

and !,5!LE #D!,F.

35. What i" the diferen&e ,et;een ?REAK and ONTINUE)

Brea= %eans loop s'ould stop processing CO,T!,6E %eans loop s'ould stop

processing t'e current iteration and i%%ediatel) start processing t'e next

iteration.

sap hana frequently asked interview questions

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