I thought this would be fairly straight forward but i can't really find a simple way of doing it. I want to add a unique rownumber to a source dataset in a ADF Mapping Dataflow. In SSIS i would have done this with a script component but there's no option for that as far as i can see in ADF. I've looked for suitable functions in the derived columns expressions editor and also the aggregate component but there doesn't appear to be one.
Any ideas how this could be achieved?
Thanks
Many options:
Add a surrogate key transform
Hash row columns in Derived Column using SHA2
Use the rowNumber() function in a Window transformation
Give those a shot and let us know what you think
I did like this:
Add a Column with the same value to all the rows (I've used an integer with value = 1);
Added a window, using the column create previously on step 1 (Over);
Add a column on step 4 to window (window columns) with any name and rowNumber() as expression;
Related
I would like to create some marks, where the information of the size comes from one dataset and the information of the color comes from another dataset.
Is this possible?
Or can I update created marks (created with dataset 1) by using information from a second dataset?
Yes, you can do it.
You can use lookup transform provided there is a lookup key in both datasets.
In this example, 'category' is the key that performs lookup transform
sorry for the basic question, I am coming from PowerQuery background, and started using ADF for a new Project. first I started wrangling data flows and fill down values is not supported, Now I am trying with mapping data flow and I can't find in the documentation how to fill down a value ?
see example I have the ID column and looking to add FILL_ID
This data flow script snippet will do the trick:
source1 derive(dummy = 1) ~> DerivedColumn1
DerivedColumn1 window(over(dummy),
asc(movie, true),
startRowOffset: -1L,
endRowOffset: 0L,
Rating2 = first(coalesce(Rating))) ~> Window1
Window1 derive(Rating = iif(isNull(Rating),Rating2,Rating)) ~> DerivedColumn2
Create a new data flow
Add a Source transformation that points to your text file
Click on the script behind button on top right of browser UI
Hit Enter to create newline at the bottom the script
Paste the above snippet and click OK
You should now see a Derived Column, Window, and another Derived. Go into the Window and 2nd Derived Column to change my column names to yours for sort and the coalesce function. THen in the 2nd Derived Column, pick the names of your columns.
The first derived creates a dummy var that you'll need because your use case is to pick the previous non-null value across the entire dataset.
The Window sorts the data because your use case requires it and the window column creates a new column that uses coalesce() to find first non-null.
The 2nd Derived Column swaps in the previous value is the current is NULL.
You can use DerivedColumn.
1.add a column or select a column exist in your source.
2.enter an expression,if value of your column is null(you can check this by using Data preview),you can use iifNull function.About expression in dataflow,you can refer this.
I have a job where I am getting a flow into tOracleOutput where I am updating the table. Now, I have to update that table using an SQL statement, which I guess we have option in Advanced settings of tOracleOuptut, but I don't know how to use it or you can say that I am not getting the settings properly. I referred to official documentation but could not understand. Can any one explain the fields like Name, SQL expression, Position, Reference Column in a better way?
the SQL query which I am using is:
update set COL1=SOMETHING1
where COL2=SOMETHING2
Now, value for COL1 is coming from the flow but COL2 is some column in the table which is not coming from the flow.
Have a look to tOracleRow for such a case.
Hope this helps.
TRF
Using tOracleOutput is helpful when a ready data source (table or file (...) with same columns as destination) the more elaborate your query is, the more you should do as TRF said (and use tOracleRow), but here's an example to your question:
file contain 3 column,
DB table of destination contains 4 column, where the 4th is the date of update, (the first 3 are identical to the input)
so you add the destination's column's name in Name and put the SQL function for the date (eg: SYSDATE) and where to put it (Position) in reference to a column of your choice (Reference Column)
In my view it helps avoid using tMap for a miserable additional column when you want to Insert, but you want to Update, in which case the component doesn't offer the additional column section, plus I don't think you can add the WHERE clause here
Hope it helps
I have some data which I need to pivot in Talend. This is a sample:
brandname,metric,value
A,xyz,2
B,xyz,2
A,abc,3
C,def,1
C,ghi,6
A,ghi,1
Now I need this data to be pivoted on the metric column like this:
brandname,abc,def,ghi,xyz
A,3,null,1,2
B,null,null,null,2
C,null,1,6,null
Currently I am using tPivotToColumnsDelimited to pivot the data to a file and reading back from that file. However having to store data on an external file and reading back is messy and unnecessary overhead.
Is there a way to do this with Talend without writing to an external file? I tried to use tDenormalize but as far as I understand, it will return the rows as 1 column which is not what I need. I also looked for some 3rd party component in TalendExchange but couldn't find anything useful.
Thank you for your help.
Assuming that your metrics are fixed, you can use their names as columns of the output. The solution to do the pivot has two parts: first, a tMap that transposes the value of each input-row in into the corresponding column in the output-row out and second, a tAggregate that groups the map's output-rows according to the brandname.
For the tMap you'd have to fill the columns conditionally like this, example for output colum named "abc":
out.abc = "abc".equals(in.metric)?in.value:null
In the tAggregate you'd have to group by out.brandname and aggregate each column as sum ignoring nulls.
I am pretty new to Pentaho so my query might sound very novice.
I have written a transformation in which am using CSV file input step and table input step.
Steps I followed:
Initially, I created a parameter in transformation properties. The
parameter birthdate doesn't have any default value set.
I have used this parameter in postgresql query in table input step
in the following manner:
select * from person where EXTRACT(YEAR FROM birthdate) > ${birthdate};
I am reading the CSV file using CSV file input step. How do I assign the birthdate value which is present in my CSV file to the parameter which I created in the transformation?
(OR)
Could you guide me the process of assigning the CSV field value directly to the SQL query used in the table input step without the use of a parameter?
TLDR;
I recommend using a "database join" step like in my third suggestion below.
See the last image for reference
First idea - Using Table Input as originally asked
Well, you don't need any parameter for that, unless you are going to provide the value for that parameter when asking the transformation to run. If you need to read data from a CSV you can do that with this approach.
First, read your CSV and make sure your rows are ok.
After that, use a select values to keep only the columns to be used as parameters.
In the table input, use a placeholder (?) to determine where to place the data and ask it to run for each row that it receives from the source step.
Just keep in ming that the order of columns received by the table input (the columns out of the select values) is the same order that it will be used for the placeholders (?). This should not be a problem with your question that uses only one placeholder, but keep that in mind as you ramp up using Pentaho.
Second idea, using a Database Lookup
This is another approach where you can't personalize the query made to the database and may experience a better performance because you can set a "Enable cache" flag and if you don't need to use a function on your where clause this is really recommended.
Third idea, using a Database Join
That is my recommended approach if you need a function on your where clause. It looks a lot like the Table Input approach but you can skip the select values step and select what columns to use, repeat the same column a bunch of times and enable a "outer join" flag that returns the rows without result from the query
ProTip: If you feel the transformation running too slow, try to use multiple copies from the step (documentation here) and obviously make sure the table have the appropriate indexes in place.
Yes there's a way of assigning directly without the use of parameter. Do as follows.
Use Block this step until steps finish to halt the table input step till csv input step completes.
Following is how you configure each step.
Note:
Postgres query should be select * from person where EXTRACT(YEAR
FROM birthdate) > ?::integer
Check Execute for each row and Replace variables in in Table input step.
Select only the birthday column in CSV input step.