Output preview not available for Inner Join

[darshthakkar]

Hi Team,

I’m using an Inner Join and observing that the output preview doesn’t appear. Is this an expected behaviour?
I however, have access to the data I’m expecting out of Inner join (as I’m writing to an excel file) but using a mapper after Inner Join doesn’t help as there is no data in the input schema of the mapper. How do I filter the data that I don’t need out of the Inner Join when the preview is not available and Input schema is showing nothing?

I also have access to the other filtered data as I have enabled the error view in Inner Join and that does have an output preview to it.

Appreciate your help and time on this.

Best Regards,
Darsh

[darshthakkar]

Seems like using mapper after Inner Join is practically impossible. Is there a workaround?

[koryknick]

@darshthakkar - I think you may be running into a common misunderstanding with the Data Preview functionality. By default, SnapLogic pulls only the first 50 records for preview into each snap. If the two sources you are reading from do not have any records that align to meet your join criteria with an inner join, then nothing will be output.

For example, if SourceA contains records such as CustomerId from 1 to 50, and SourceB contains records with CustomerId from 2000 - 2050, then the inner join doesn’t match anything and all records are effectively filtered.

You can try updating your User Settings / Preview Document Count as high as 2000 to see if that helps:

Or you can set filter conditions on your source data to ensure alignment of data that will match in your Join - in the case of the CustomId values I gave, you could set a filter condition in your database select to pull only records with CustomerId values of 1-50.

To prove if my theory is correct, you can switch your Join to a Left Outer join type and see that documents will flow through to the output view of the Join.

[darshthakkar]

Thank you @koryknick for responding to this.
I will try with 2 sample flat files and test the functionality of Inner Join. While I was reading your explanation, I felt it was right, Left Outer Join always gives me an output however that is not the case with Inner Join.

What am I going to do next would be:

1. Prepare 2 flat files with IDs similar
2. Use a sort before Join
3. Use Inner Join
4. Check the Output preview
5. If (4) fails (highly unlikeable), go to settings and change the preview count to max

Would you suggest any other steps than the ones stated above? I can keep you posted once I test this.

Regards,
Darsh

[darshthakkar]

koryknick:

By default, SnapLogic pulls only the first 50 records for preview into each snap. If the two sources you are reading from do not have any records that align to meet your join criteria with an inner join, then nothing will be output.

If you don’t mind, can I ask you something?
Why would I not be able to see anything under input schema for the mapper attached to the Inner Join? Is the data not matching for the first 50 records the reason?