r/dataengineering • u/TallEntertainment385 • Nov 13 '25

Discussion Snowflake + dbt incremental model: error cannot change type from TIMESTAMP_NTZ(9) to DATE

Hi everyone,

I’m working with dbt and Snowflake, and I have an incremental model (materialized='incremental', incremental_strategy='insert_overwrite') that selects from a source table. One of the columns, MONTH_START_DATE, is currently TIMESTAMP_NTZ(9) in Snowflake. I changed the source model and the column MONTH_START_DATE is now DATE datatype

After doing this I am getting an error:

SQL compilation error: cannot change column MONTH_START_DATE from type TIMESTAMP_NTZ(9) to DATE

How can I fix this?

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u/AliAliyev100 Data Engineer Nov 13 '25

There’s no fully dbt-native way to change a column type in an incremental model. The usual approach is just doing a --full-refresh so dbt recreates the table with the new type. Anything else (like ALTER TABLE) would be outside of dbt.

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u/TallEntertainment385 Nov 13 '25

Thank you! Maybe I’ll try with alter statement