I have a migration job from Oracle to PostgreSQL (PG). Null values in Oracle appear to be empty strings in PG. Null values are in both numeral and char data types. If I want all null values in Oracle to be also null value in PG, what transformer or method should I use for this migration? Thanks.
Question
Null value handling from Oracle to PostgreSQL (PG)
@bluewater FME should be preserving the <null> values from Oracle to PostgreSQL . If you look at your data using FME Data Inspector or Visual Preview you should see <null> 
Check that your source Oracle data does actually have <null> field values and that they are not just Empty or Blank. You can use the NullAttributeMapper transformer to force values to <null>
Thank you for your kind comment, @Mark Stoakes. Yes, I have confirmed that the original Oracle tables have null values and those null values are not coming through correctly in the destination PostgreSQL database table.
I tried to use NullAttributeMapper transformer, but I may not be using that correctly. It is still not working.
@bluewater You probably have to take this up with your local FME support organization. As far as I can tell, support for <null> is working OK in FME between Oracle & PostgreSQL. So there must be something else going on. (Unless you are using a very old version of FME before we added <null> support circa 2014/2015)
I use 2018 version. Ok, I will seek support from our vender. Thanks you for your time!