54001: statement_too_complex

What does it mean?

The statement is more complex than PostgreSQL can process; usually very deeply nested expressions or many nested operators make the expression tree exceed the parser/planner stack limit. Belongs to Class 54 (program_limit_exceeded).

Why does it happen?

Excessively deep parentheses/nested subqueries or OR/AND chains; huge auto-generated WHERE ... IN (...) lists; or very large expression trees arising from recursive views. The max_stack_depth limit is reached.

How to fix it

Simplify the query: move long IN lists into a temporary table or a VALUES set and JOIN to it; break up nested expressions; review huge ORM-generated queries. If truly necessary and your OS stack limit allows it, raise max_stack_depth carefully (e.g. SET max_stack_depth = '4MB';) but keep it below the OS ulimit.