topic Transfer rows from job to job in Talend Studio

Transfer rows from job to job

Anonymous — Mon, 27 Apr 2020 15:29:20 GMT

Hi, I'm trying to design a job with several subjobs.

The idea is to separate a big transformation in several readable steps.

I have a parent job that call my first child job. This job end with a tBufferedOutput (is it the right output?)

Then in my parent job, with a main connexion, I direct the flow from my first to my second child job.

The question is, how can I retrieve my rows in my second child job?

I tried with a buffered input, but no success.

I attached some screenshot to make this more understandable.

Thank you for your help!

Re: Transfer rows from job to job

Anonymous — Mon, 27 Apr 2020 15:43:43 GMT

Make sure schema of tBufferOutput in child job is matches with schema in tRunJob in parent job. Based on screen shots - it appears your job is running but not showing output.

Re: Transfer rows from job to job

Anonymous — Mon, 27 Apr 2020 15:55:45 GMT

Yes it's the same schema I used the same metadatas.

I joined new screenshots.

Also, it seems that the main connecion between the job is not good, as it seems the second child is call once for each row from the first child!

I tried to use OnSubJobOk but no success either...

I join another screenshot for it

onSubJobOk.png
child2.png
working fine.png

Re: Transfer rows from job to job

Anonymous — Mon, 27 Apr 2020 19:07:44 GMT

Your child job should end with tBufferOutput. That will allow parent job to read output from it. See the screen shot attached.

ChildJob.PNG
ParentJob.PNG

Re: Transfer rows from job to job

Anonymous — Mon, 27 Apr 2020 20:15:43 GMT

Yes I made this work, but my problem is when I try to reinject the rows in another child job

Re: Transfer rows from job to job

BhavikaW — Tue, 28 Apr 2020 07:40:18 GMT

The first child job should end with tbufferoutput. Then the schema of tbufferoutput should match with schema of trun job of 1st child job in parent job. Then use tjavarow between 1st child job and 2nd child job and pass the data from one child job to other by generating the code or the values can be stored in globalMap variable using globalMap.put method and retrieve the values by passing them in context parameters in 2nd job

Re: Transfer rows from job to job

Anonymous — Tue, 28 Apr 2020 09:04:13 GMT

Using the context seems a bit tedious but I will try.

So far I solved my issue by storing my rows in a file at the end of child1 then using that file to continue the treatment in child 2, but I guess this is not good practice and bad for the performances.

May be I can store the result in a hash map type in-memory database. Using the tBuffer input and output seemed to be the most simple way.

Re: Transfer rows from job to job

Anonymous — Tue, 28 Apr 2020 09:41:32 GMT

What do best practices advise for this kind of case?

Or may be the way I split my transformation is not right in the first place? Else everyone would have this kind of issue for any transformation with more than a few steps.

Re: Transfer rows from job to job

Anonymous — Wed, 29 Apr 2020 11:35:06 GMT

This feel like very standard stuff, yet I can't find anything but taht convoluted context solution.

How do you guys do it?

I have a file, I want to make several transformations on it and separate them in several jobs.

The goal is to have a parent job calling each successive children jobs in sequence. First child job should read the initial file, last child should write the result.

I can get the flow out of the child with tBufferOut, and get it in the parent with tBufferIn, but I can never reinject it in the next child without creating a huge list of context values with every single columns in it? Why couldn't I get the flow in the next child using a simple tBufferIn, tuo get the tBufferOut of the previous child?

Thanks a lot for your help. Let me know if you have another way of splitting a big job in several subjob, but using the salme flow of data during the whole process.

Re: Transfer rows from job to job

billimmer — Wed, 29 Apr 2020 14:35:08 GMT

Use the tHashInput and tHashOutput instead. See:

https://community.talend.com/t5/Migration-Configuration-and/Where-are-the-tHashInput-and-tHashOutput-components/ta-p/309

Re: Transfer rows from job to job

Anonymous — Wed, 29 Apr 2020 14:50:01 GMT

It does not seem to work either.

Here is my parent job:

Child1:

Child2:

The problem is that the tHashInput in child2 won't find tHashOutput from child1:

What am I doing wrong?

Re: Transfer rows from job to job

billimmer — Thu, 30 Apr 2020 20:42:44 GMT

No, my bad. The tHash components do not work between subjob and main job.

From looking at this it seems the only good way is to use some kind of persistent storage, such as a DB or Disk.

Re: Transfer rows from job to job

Anonymous — Thu, 30 Apr 2020 22:52:32 GMT

I find it very strange that this is not a standard request. How do you guys do? You design some monster jobs? XD

Re: Transfer rows from job to job

billimmer — Fri, 01 May 2020 14:50:49 GMT

For jobs where I have many transformations involving multiple tables I use a single text file with all the SQL for each transformation step. Then in my Talend job I read the sql file and split it into one file per SQL statement, and then I iterate through these, logging as I go.

I use a begin/end statement delimiter with a comment in the text file so that the logging is descriptive. I also include variables in the SQL, and replace them with values from the Talend job before execution (such as dates, etc)

This makes it easier for me to keep track as all the transformation are in one file, with many comments.

EDIT: Here is the subjob that splits the file:

Re: Transfer rows from job to job

Anonymous — Fri, 01 May 2020 15:04:39 GMT

Ok, that's interesting, I will study that option.

Thanks a lot!

Re: Transfer rows from job to job

billimmer — Fri, 01 May 2020 15:26:25 GMT

A few other thoughts - the tloop above is used to create a manifest (a list of the sql files created, in the order they should be run). The split happens in the block above. Here is the job that reads the manifest and process each file.