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PostgreSQL error code

PostgreSQL error 42P18

42P18 is the SQLSTATE PostgreSQL reports for indeterminate datatype, in class 42, Syntax Error or Access Rule Violation.

SQLSTATE42P18
Condition nameindeterminate_datatype
Class42 — Syntax Error or Access Rule Violation

Reproduce it, then fix it

An empty ARRAY[] has no elements to take a type from. Cast it to the array type you want. Run the broken query to see the error, then switch to the fixed one. Edit either freely; every run is rolled back.

SELECT name, ARRAY[] AS tags FROM products;
SELECT name, ARRAY[]::text[] AS tags FROM products;

Source: PostgreSQL documentation, Appendix A