U118: Column must appear in the GROUP BY clause

Example Postgres Log Output:

ERROR: column "identifier_column.value_column" must appear in the GROUP BY clause or be used in an aggregate function at character 8
STATEMENT: SELECT identifier_column, MAX(value_column) FROM my_table

Explanation:

This error occurs since you've specified an aggregate function (e.g. MAX(...)) alongside a regular column in the query's target list, but you didn't specify the regular column as one of the columns to be grouped by.

Usually you would encounter this whilst testing on a development/staging system, or when mistyping a one-off query on a production system.

Recommended Action:

Be aware of GROUP BY and aggregation logic in PostgreSQL and be sure to specify the correct columns to aggregate by.

Learn More:

• Postgres Documentation: The SQL Language - Aggregate Functions