topic Re: Order of execution in Talend Studio

Order of execution

Anonymous — Fri, 01 Sep 2017 11:36:13 GMT

I am having difficulty understanding how Talend runs the components of a job.

In the screen-shot below, I read a varchar from a Microsoft SQL Server table (table has only one row and one column, with a varchar (10) containing ‘190’).

I then want to store this string in a Variable for later use.

The components seem to execute in parallel, instead of one after another. I see from the forum that this is a common problem, but I don’t understand it.

tJava_1 contains the simple code shown below, but it always displays Null instead of the expected string ‘190’.

tJava_1 contains this simple code –

System.out.println("tJava_1 " + (String)row2.Num_Days);

globalMap.put("myKey", (String)row2.Num_Days);

System.out.println("myKey is " + globalMap.get("myKey"));

Here is what I get –

Starting job Medora_test_Copy_2_Copy at 10:40 01/09/2017.

[statistics] connecting to socket on port 3734

[statistics] connected

tJava_1 null

myKey is null

Num_Days: 190

[statistics] disconnected

Job Medora_test_Copy_2_Copy ended at 10:40 01/09/2017. [exit code=0]

It looks like the code in tJava_1 executes before tMSSQLInput_1 has even started reading from SQL Server.

How can I stop the tJava_1 component from executing until the tMSSqlInput_1 component has finished please?

Is there an explanation on the web of how Talend controls order-of-execution of the components please?

I think I understand why I am confused, but not how to escape from the confusion

Regards

Jon

R.J Lester

Data Warehouse Developer

Customer Support and Innovation Centre

Maidstone & Tunbridge Wells Trust Phone: 01622 225616

Email: jon.lester@nhs.net

Re: Order of execution

TRF — Fri, 01 Sep 2017 11:59:46 GMT

The order is what you expect but the result on the console (from tLogRow) comes when the job is finished.

Change the tJava by a tJavaRow component to access the tMSSQLInput_1 result (get the fileds value using input_row.Num_Days instead of row2.Num_Days).

Re: Order of execution

Anonymous — Fri, 01 Sep 2017 12:09:54 GMT

Thanks very much TRF,

My small job works fine now!

I didn't understand the tJavaRow_1 component, so I had not tried it until I saw your answer.

This Talend Open Studio is very useful and I think it should be used more in the NHS (National Health Service, ie healthcare in the UK)

Regards

Jon

Re: Order of execution

TRF — Fri, 01 Sep 2017 12:15:15 GMT

Great! Thank's for the Kudo.

I'm not from Talend, but Talend people will be happy of your comment.

You're welcome if you need more help.