Issue with Talend tDBOutput Creating NOT NULL Columns in Snowflake

skeletonred — Thu, 13 Mar 2025 00:20:59 GMT

Hi Community,

I'm facing an issue with my Talend job while trying to bulk load nearly 100 tables from MySQL to Snowflake. The problem is that when tDBOutput creates tables in Snowflake, some columns are automatically set as NOT NULL, even though I haven't explicitly defined them as such.

This is causing errors during data loading when NULL values are present in those columns.

Snowflake table query:

Job Design & Settings:

tDBInput (MySQL Source):

Using Dynamic Schema Type to handle all 100 tables.

No manual column definitions to avoid complexity.

tMap (Transformation Layer):

No transformations or modifications applied.

tDBOutput - snowflake:

Advanced settings in tDBOutput :

Error:

Caused by: net.snowflake.client.loader.Loader$ConnectionError: State: COPY_INTO_TABLE, COPY INTO "TEST_20250313_105751_794_1" FROM '@~/TEST/INSERT/20250313_105751_794_2BVBLI_1' on_error='ABORT_STATEMENT' file_format=( field_optionally_enclosed_by='"' empty_field_as_null=true), NULL result in a non-nullable column

Challenges:

Since I'm dealing with 100+ tables, manually defining column constraints is not feasible. I need a way to ensure that all columns are created as NULLABLE by default in Snowflake.

Questions:

How can I prevent tDBOutput from automatically setting columns as NOT NULL when creating tables in Snowflake?
Is there a way to enforce NULLABLE constraints dynamically for all tables without manually altering each schema?

Would appreciate any guidance or best practices for handling this issue efficiently.

Thanks in advance!

Best regards,
Nikhil

Re: Issue with Talend tDBOutput Creating NOT NULL Columns in Snowflake

gouravdubey5 — Thu, 19 Feb 2026 09:06:45 GMT

Hello,

Pre-create target tables manually in Snowflake with all columns explicitly defined as NULLABLE before loading data.

In your Talend job, don’t let tDBOutput auto-create tables — instead point it to the pre-defined schema.

If you must create tables dynamically, use custom SQL (e.g., ALTER TABLE) after creation to set columns to NULLABLE before loading.

Consider handling column metadata in a tMap or routine to mark fields as NULLABLE before output.

Talend help on defining nullable values / outputting nulls in mappings
https://help.qlik.com/talend/en-US/components/8.0/tmap/outputting-blank-values-as-null-or-fixed-values

Thanks,

Gourav

topic Re: Issue with Talend tDBOutput Creating NOT NULL Columns in Snowflake in Talend Studio

Issue with Talend tDBOutput Creating NOT NULL Columns in Snowflake

Re: Issue with Talend tDBOutput Creating NOT NULL Columns in Snowflake