This blog will detail you the use and exact working of a Datastage pivot stage with an example...
Many people have the following misconceptions about Pivot stage.
1) It converts rows into columns
Many people have the following misconceptions about Pivot stage.
1) It converts rows into columns
2) By using a pivot stage, we can convert 10 rows into 100 columns and 100 columns into 10 rows
3) You can add more points here!!
Let me tell you that a pivot stage only CONVERTS COLUMNS INTO ROWS and nothing else. Another fact about the pivot stage is that it's irreplacable i.e no other stage has this functionality of converting columns into rows!!! So , that makes it unique, doesn't!!!
Let's cover how exactly it does it....
For example, lets take a file with the following fields: Item, Quantity1, Quantity2, Quantity3....
Item~Quantity1~Quantity2~Quantity3
Let me tell you that a pivot stage only CONVERTS COLUMNS INTO ROWS and nothing else. Another fact about the pivot stage is that it's irreplacable i.e no other stage has this functionality of converting columns into rows!!! So , that makes it unique, doesn't!!!
Let's cover how exactly it does it....
For example, lets take a file with the following fields: Item, Quantity1, Quantity2, Quantity3....
Item~Quantity1~Quantity2~Quantity3
ABC~100~1000~10000
DEF~200~2000~20000
GHI~300~3000~30000
Basically you would use a pivot stage when u need to convert those 3 Quantity fields into a single field whch contains a unique Quantity value per row...i.e. You would need the following output
Item~Quantity
Basically you would use a pivot stage when u need to convert those 3 Quantity fields into a single field whch contains a unique Quantity value per row...i.e. You would need the following output
Item~Quantity
ABC~100
ABC~1000
ABC~10000
DEF~200
DEF~2000
DEF~20000
GHI~300
GHI~3000
GHI~30000
How to achieve the above using Datastage???
In this case your source would be a flat file. Read it using any file stage of your choice: Sequential file stage, File set stage or Dataset stage. Give 4 columns inthe Output column derivation tab.
Now connect a Pivot stage from the Tool pallette to the above output link and create an output link for the Pivot stage itself (fr enabling the Output tab for the pivot stage).
Unlike other stages, a pivot stage doesn't use the generic GUI stage page. It has a stage page of its own. And by default the Output columns page would not have any fields. Hence, you need to manually type in the fields. In this case just type in the 2 fiel names : Item and Quantity. However manual typing of the columns becomes a tedious process hen the number of fields is more. In this case you can use the Metadata Save/Load feature. Go the input columns tab of the pivot stage, save the table definitions and load them in the output columns tab. This is the way I use it!!!
Now, you have the following fields in the Output Column's tab...Item and Quantity....Here comes the tricky part i.e you need to specify the DERIVATION ....In case the field names of Output columns tab are same as the Input tab, you need not specify any derivation i.e in this case for the Item field, you need nt specify any derivation..Chk image below.. But if the Output columns tab has new field names, you need to specify Derivation or you would get a RUN-TIME error for free....
How to achieve the above using Datastage???
In this case your source would be a flat file. Read it using any file stage of your choice: Sequential file stage, File set stage or Dataset stage. Give 4 columns inthe Output column derivation tab.
Now connect a Pivot stage from the Tool pallette to the above output link and create an output link for the Pivot stage itself (fr enabling the Output tab for the pivot stage).
Unlike other stages, a pivot stage doesn't use the generic GUI stage page. It has a stage page of its own. And by default the Output columns page would not have any fields. Hence, you need to manually type in the fields. In this case just type in the 2 fiel names : Item and Quantity. However manual typing of the columns becomes a tedious process hen the number of fields is more. In this case you can use the Metadata Save/Load feature. Go the input columns tab of the pivot stage, save the table definitions and load them in the output columns tab. This is the way I use it!!!
Now, you have the following fields in the Output Column's tab...Item and Quantity....Here comes the tricky part i.e you need to specify the DERIVATION ....In case the field names of Output columns tab are same as the Input tab, you need not specify any derivation i.e in this case for the Item field, you need nt specify any derivation..Chk image below.. But if the Output columns tab has new field names, you need to specify Derivation or you would get a RUN-TIME error for free....
For our example, you need to type the Derivation for the Quantity field as
Column name Derivation
Column name Derivation
Item Item (or you can leave this blank)
Quantity Quantity1, Quantity2, Quantity3.
Just attach another file stage and view your output!!! So, objective met!!!
Disclaimer: Datastage professionals might feel this blog as very kiddish, but do note that these r fewer such ppl and this blog is for all the DS beginners...Hope this blog helps....Suggestions and improvements welcome!!!
