invalid_column_reference GROUP BY position … is not in select list — 42P10

Symptoms

A GROUP BY used a positional number that does not correspond to a column in the select list. PostgreSQL raises SQLSTATE 42P10 (invalid_column_reference).

• GROUP BY n where n exceeds the number of output columns.
• Positional grouping references the SELECT list by index.
• Common after editing the select list.

What the server log shows

ERROR:  GROUP BY position 5 is not in select list

Why PostgreSQL raises this — what the manual says

As Section 7.2.3 The GROUP BY and HAVING Clauses explains:

A GROUP BY item written as a positional number refers to the ordinal position of an output column in the select list; a number that does not correspond to any select-list column (for example GROUP BY 5 when only three columns are selected) is rejected.

Positional GROUP BY refers to the n-th item in the select list. When n is larger than the number of output columns (or otherwise invalid), there is no column to group by and PostgreSQL reports 42P10.

Common causes

• A position number greater than the count of select-list items.
• The select list changed but the positions did not.
• Off-by-one positional references.

How to fix it

1. Use a valid position within the select list range.
2. Group by the column name/expression instead of a number.
3. Recount the select-list items after edits.

Related & next steps

• SQLSTATE 42P10 — Invalid Column Reference (full reference)
• Message: ORDER BY position is not in select list
• Glossary: GROUP BY

Reference: PostgreSQL 18 Section 7.2 “Table Expressions”.