I am designing a ADF pipeline that copies rows from a SQL table to a folder in Azure Data Lake. After that the rows in SQL should be deleted. But for this delete action takes place I want to know if the number rows that are copied are the same as the number of rows that were I selected in the beginning of the pipeline.
Is there a way to get the rowcount fo the copy action and use this in another action (like a lookup)
Edit follow up question:
Bo Xiao's answer is OK. BUt then I have a follow up question. After the copy-activity I put an If Condition with the following expression:
#activity('LookUpActivity').output.firstRow.RecordsRead == #{activity('copyActivity').output.rowsCopied
But then I get the error: #activity('LookUpActivity').output.firstRow.RecordsRead == #{activity('copyActivity').output.rowsCopied
Isn't it possible to compare output parameters of two activities to see if this is True?
extra edit: I just found an error in this piece of code. I forgot a "{" at the begin of the code. But then the code is still wrong. To compare two outputs from earlier activities the code must be:
#equals(activity('LookUpActivity').output.firstRow.RecordsRead,activity('copyActivity').output.rowsCopied)
You can find copied rows in activity output as pictured below.
And you can use the output value like this:
#activity('copyActivity').output.rowsCopied
Related
I'm doing a large-scale project with multiple pipelines, millions of records per pipeline. I'm trying to develop a generic skipped row capture process.
What I need to do is: for every source row skipped due to any error encountered on the attempted load, I want to capture a key column value from the row and write it to a distinct log file (or separate DB table row). This can't be summary data: for each individual row that fails, I need to capture the row key from that row so we can review/re-load later (I will add in system variable values to identify pipeline, component, time stamp, etc). Pipeline must complete with all successful rows loaded, all unsuccessful rows logged.
This is no-brainer functionality in most ETL tools; I have to be overlooking something in ADF, because I can't find a way to do this. Appreciate any/all suggestions.
You can enable Fault tolerance and choose Skip incompatible rows option. It will skip the incompatible rows between source and target store during copy data. e.g. type and field mismatch or PK violation.
Then you can enable session log and choose Warning log level in copy activity to log skipped rows. Finally, you can save your log file in Azure Storage or Azure Data Lake Storage Gen2.
Reference:
https://learn.microsoft.com/en-us/azure/data-factory/copy-activity-fault-tolerance
https://learn.microsoft.com/en-us/azure/data-factory/copy-activity-log
With your first copy activity, check the fault tolerance option in 'settings' to log skipped fault rows.
Make sure to place your rows key column, as the first in the mapping definition.
Get the copy activity logFilePath from the activity output into a variable
Add another copy activity to load skipped rows into relational table
it source path will be the variable holds logFilePath
Set the file path type to: 'Wildcard file path'
Keep the 'Wildcard file path' empty
Will be the value in Wildcard file name
Make sure that the delimited file dataset escape character is set to quotations.
The OperationItem field of the lg file holds your record fields seperated by ,; because we placed the rowID first on mapping, it will appear first in OperationalItem as well.
Goodluck
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 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.
i've got the following problem.
I have several tMaps, each has a lookup and at the end all the data is written in a db. The following mockup shall illustrate it:
There can be values in the main data stream which are not found in the lookup tables. For this values there is a rejected path which catches them from the specific tMap.
Requirements:
In case of a rejected inner join the looked up value shall be set to a default value (for example 0, which could be done in the schema of the tMap) and after that these "corrected" records should be added to the "normal" main data flow and process the next lookup.
The tUnite component is not able to handle this cases because it can not exist in a data flow loop.
Does anybody got an idea how to solve this problem?
Cheers.
The answer was so easy that i didn't got it in the first conception. I just have to change the join model from inner to left-join so all the formal rejected values will have a null value in it. Afterwards i can check the columns in the tmap and set them on a default value if they are null.
row1.id == null ? 0 : row1.id
Cheers.
If I understand correctly what you are trying to accomplish you will have to have staging files or staging tables on the database. Once you get the rejected rows, write them on a file or table. The accepted files will go also to a staging table(different than the rejected). Then you can union both tables or files by reading them. The key point is having a staging structure. I attach a picture what how would it be. In the picture the staging structure is a mysql table.
Let me know if it helps!
I thought this would be an easy task, but since I am new to PDI, I could not
find out so far which transform to choose to accomplish the following:
I am using Pentaho Data Integration (former Kettle), Community Edition, to map/copy values from one table ('tasksA') of one database 'A' to another table
'tasksB' in another database B. tasksA has a column 'description' and I want
to copy these values to the column 'taskName' in 'tasksB'.
Furthermore, I have to copy each value of 'description' several times, since
in 'tasksB', there are multiple lines for each value in 'taskName'.
Maybe this would be possible by direct SQL, but I wanted to try whether
I can define this more readable with PDI, especially because in the next step I will have to extend it to other tables involved.
So I have to tell which value of
'description' has to be mapped onto which value of 'taskName' and that in
every tuple containing this value (well, sounds like a WHERE clause...) in the column 'taskName' it should be replaced.
My first experiments with the 'Table input' and 'Table output' steps
did not work when I simply drew a hop between them and modifying the 'database
fields' tab of the 'Table output' step, which generated 'drop column' statements
in the resulting SQL which is not what I want. I don't want to modify the schema, just copy the values.
Would be great if someone could point me to the right steps/transforms needed,
I worked through the first examples from the Pentaho Wiki and have got the 'Pentaho Kettle Solutions' book of Casters et al. but could find out how
to do solve this. Many thanks in advance for any help.
If I got this right, you should use the Table Input connected to a "Insert/Update" step.
On the Insert/Update step you need to inform the keys from tasksA where should be looked up on tasksB. Then define which fields on tasksB should be updated: description (as stream field) -> taskName (as the table field).
Keep in mind that if this key is not found, a row will be inserted on tasksB. If it is not what you plan, you'll need to build something like: Table Input -> Database Lookup -> Filter Rows -> Insert/Update
#RFVoltolini has a good answer. Alternatively you could go
Table Input -> Update
And connect the error output to something else like a Text file output.