DSXchange

I mean precision 20 with data type VarChar.

As far as I am aware, REST is not supported.

Everything in the Web Services PACK uses SOAP, not REST. (There's a certification question about that!) I expect "they" thought REST to be too unstructured to be rigorous.

... or a Modify stage.

You can always tell the difference for data type conversion functions:
To
from

Sounds like a corrupted export. Try exporting this sequence again.

Almost but not quite. Records with composite weight below clerical cutoff are non-matches (residuals), at least for that pass. Otherwise good. Clerical cutoff must be set <= match cutoff.

date_from_timestamp() is a Modify stage function, not a Transformer stage function.

VarChar or VarChar(20)??

It appears that the entry in tnsnames.ora for this database does not have a resolvable SID.

select count(*) from all_users where clue > 0;
COUNT(*)
----------
0

Shared containers have a button that allows you to validate that the metadata is the same on the links that pass through its "walls". In your case that seems to be link1 with link2 and link3 with link4.

Something else (depending on your precise requirement). I envisage checking the exit status - and/or the output - of each Execute Command activity within the job sequence logic.

You can use any SQL that is valid for the database, provided that the rows produced match the metadata in your job design.