ERROR DB Query Reader - Execute failed: Spec must not be null! (ORACLE)

[raul_viana]

Hello

When trying to do some queries i noticed that, despite me being able to use the DB Table Selector node successfully, i always got an error while trying to run any valid query on DB Query Reader, even though when i evaluated the query it seemed to be ok.
I’ve tried this on 4.2.2 and 5.1.1, and it yielded the same results.
Error is “ERROR DB Query Reader - Execute failed: Spec must not be null!”
I’m using an oracle DB
These queries run fine on Oracle SQL Developer

Played with some settings like fetch size but nothing seemed to work.
Thank you in advance!

[takbb]

Hi @raul_viana ,

Welcome to the KNIME forum!

I’ve not seen that particular error before, and it doesn’t look like any kind of Oracle exception. So lots of questions I’m afraid.

Can you see what happens if you try a different query such as:

select sysdate from dual

Also which version of Oracle are you connecting to?

Which Oracle driver is configured in KNIME?

It’s odd that you are seeing preview results and then an exception when it executes, so it is clearly connecting to the db for the preview.

Have you adjusted any of the jdbc or other advanced settings on the Oracle Connector?

I’ve been using Oracle on KNIME from 4.4 to 4.7 and 5.1 to 5.2 without seeing anything like that error.

I have found nothing on this in the forum or Google although that error messaged has cropped up a couple of times unrelated to databases.

If you have had this same error on those different versions of KNIME it sounds to me like your setup is the common link so we need to find out what you have that is common to different KNIME versions…

What OS are you on, and how did you install the Oracle connector in KNIME?

ie… Did you manually install and configure the jdbc driver, or did you install using the KNIME Oracle extension via the update dialogs?