PowerCenter Level1 Unit13

7/21/2019 PowerCenter Level1 Unit13

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Unit 13. Unconnected Lookup,

Parameters and Variables

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Unit Objectives

Understand why and how to use: Unconnected Lookup transformation

System variables

Mapping parameters and variables

Use these features in a mapping

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Unconnected Lookup

Function in the !pressioncalls the Unconnected Lookup

Unconnected Lookup

Commonly used when a lookup not needed for every record No links fromto other transformations Lookup data is called at the point in the mapping that needs it Lookup function can be set within any transformation that supports

e!pressions

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#allin$ an Unconnected Lookup

Condition is evaluated for each row but Lookup functionis called only if condition is satisfied

%%F & %'(ULL&customer)id*,+lkp.-LOOUP&order)no*, customer)id*

Condition

Lookup function

Row keys

(passed to Lookup)

Use Lookup function within a conditional statement

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Unconnected Lookup 0dvanta$es

"ata lookup is performed only for those rows whichre#uire it$ Substantial performance can be gained

EXAMPLE: % Mapping will process &''(''' rows$ )or twopercent of those rows *+'(''', the item-id value is NULL$

.tem-." can be derived from the S/U-NUM0$

(et savin$s ", lookups

%%F & %'(ULL&item)id*, +lkp.-LOOUP &sku)numb*, item)id*

Condition(true for 2 percent o4 all

ro5s*

Lookup&called onl6 5hen condition is

true*

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Unconnected Lookup Functionalit6

Onelookup port valuemay be returned for each lookup

Must check a

1eturn port in the2orts tab( ore!pression thatcalls lookup isinvalid$

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#onnected versus Unconnected Lookups

#O((#9: LOOUP U(#O((#9: LOOUP

Part o4 the mappin$ data 4lo5 'eparate 4rom the mappin$ data4lo5

;eturns multiple values &b6linkin$ output ports to anothertrans4ormation*

;eturns one value < b6 checkin$the ;eturn &;* port option 4or theoutput port that provides thereturn value

!ecuted 4or ever6 recordpassin$ throu$h thetrans4ormation

Onl6 e!ecuted 5hen the lookup4unction is called

ore visible, sho5s 5here thelookup values are used

Less visible, as the lookup iscalled 4rom an e!pression 5ithinanother trans4ormation

:e4ault values are used :e4ault values are i$nored

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>oins versus Lookups

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'6stem Variables

''''90;99%

???'ess'tart9ime

1eturns the system date value on the2owerCenter Server

Used with any function that acceptstransformation datetime datatypes Not to be used in a S3L override 4as a constant value

1eturns the system date value as astring. Uses system clock on machine

hosting 2owerCenter Server )ormat of the string is database type

dependent Used in S3L override 4as a constant value

'-':09

2rovides current datetime on the2owerCenter Server machine Not a static value

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appin$ Parameters and Variables

1epresent declared values: 5ariablescan change in value during run6time

2arametersremain constant during run6time

%pply to all transformations within a mapping

"eclared in Mappings menu )ormat is 77VariableName or 77ParameterName

Setinitiali8ed in a parameter file( specified for the session task

2rovide increased development fle!ibility Can be used in pre and post6S3L

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:eclarin$ appin$ Parameters andVariables

Mappings 9 "eclare 2arametersand 5ariables menu option

Setaggregationtype

Set optional

initial value

User6defined

*77name,

Set datatype

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Usin$ appin$ Parameters andVariables

Use parameters or variables in e!pression

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Functions to 'et appin$ Variables

'90@V0;%0AL&??Variable,value*

'9%(V0;%0AL&??Variable,value*

'9V0;%0AL&??Variable,value*

'9#OU(9V0;%0AL&??Variable*

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Parameters B Variables C %nitialiDationPriorit6

Parameters

1. Parameter 4ile

2. :eclared initial value

3. :e4ault value

Variables

1. Parameter 4ile

2. ;epositor6 value

3. :eclared initial value

". :e4ault value

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Unit 13 LabLoad 'ales Fact 9able

Staging%rea

"ataarehouse

'9E)9;0('0#9%O(''9E)P0-(9

&tables*

F0#9)'0L'&table*

#reate a mappin$ usin$+'ource uali4ier 4or homo$eneous joinUnconnected Lookup trans4ormation0$$re$ator trans4ormationappin$ parameters

#reateGrun a 5ork4lo5 4or this mappin$

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Lab ;evie5

hat did we accomplish with this lab;

3uestions;

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Unit 13 uiD

hen would you use : Unconnected Lookup transformation;

Mapping parameters and variables;

Unit 13

Documents

PowerCenter Level1 Unit13