topic Re: Main and Lookup in Talend Studio

Main and Lookup

Anonymous — Wed, 19 Sep 2018 07:17:36 GMT

Hi everyone,

What is the difference between Main row and Lookup pls?

Thanks for your responses

Re: Main and Lookup

Anonymous — Wed, 19 Sep 2018 07:28:35 GMT

Hi ,

In Talend there is nothing called as 'lookup connection' .All the input components has a main row connection . For example , if you connect a input component to tmap , it will have a main row connection and if you connect another input component to the same tmap (rightclicking - row - main) , it will be named as lookup .

On the whole for the input connection named as main we are 'looking up' the data with data of another input , so as to pull some extra information (columns) along with the data of main connected input using some common data columns.

In definition we are looking up with another input for some extra data for the main data using some common column .

Thanks ,

Praveen M.

Re: Main and Lookup

Anonymous — Wed, 19 Sep 2018 11:23:17 GMT

A Main row entering a tMap is the source that drives the data through the component. The Lookup is used to compare/reference to that Main row. If you Main input has 10 rows, then the tMap will consume each of those rows and use the Lookup against each of those rows. If the Main has 0 rows and the Lookup has 100 rows, no rows will be consumed and no rows will be returned. This is why you cannot carry out a full outer join with a single tMap.

Re: Main and Lookup

Anonymous — Wed, 19 Sep 2018 12:26:24 GMT

Thank you guys It is possible to do a juncture in use main? If not, how to do this?

Re: Main and Lookup

Anonymous — Wed, 19 Sep 2018 12:33:51 GMT

Can you describe exactly what you want to do?

Re: Main and Lookup

Anonymous — Wed, 19 Sep 2018 13:27:47 GMT

Hi Mialy,

The answers related to the query related to main and lookup can be verified in below KB article. Its a four part series and my recommendation will be to go through the full series. But if time constratinst are there, please refer the section related to tmap.

https://www.talend.com/blog/2017/01/05/talend-job-design-patterns-best-practices-part-4/

For the query related to juncture, you have created another topic in forum. So lets use that link to track the question (link shown below).

https://community.talend.com/t5/Design-and-Development/Table-juncture/td-p/134401/jump-to/first-unread-message

If the detils provided has helped you to resolve your query, could you please mark the topic as closed? Kudos are also welcome.

Warm Regards,

Nikhil Thampi