Bug reference: 16368 Logged by: Elvis Pranskevichus Email address: elprans@gmail.com PostgreSQL version: 12.2 Operating system: Gentoo Linux Description:
Consider the following function:
CREATE OR REPLACE FUNCTION intfmt(input text, fmt text) [...] SELECT CASE WHEN fmt IS NULL THEN input::bigint ELSE to_number(input, fmt)::bigint END; [...] SELECT [...]
intfmt('123,456', q.fmt) AS "out"
The expected result is the integer 123456, but the query fails with:
ERROR: invalid input syntax for type bigint: "123,456" CONTEXT: SQL function "intfmt" during inlining
Which means that somehow during inlining of "intfmt" Postgres incorrectly takes the first branch in the `CASE` expression.
During inlining the case expression becomes:
CASE WHEN q.fmt IS NULL
THEN '123,456'::bigint
ELSE to_number('123,456', q.fmt)
END;
It doesn't "take" a branch - it turns variables into constants and, as written, some of those constants are invalid for the types they are being assigned to.
This only happens in the presence of the "first_value" window call in the nested query.
The ability to optimize, and how, depends on the whole query.
I don't actually know whether this is a bug or just an expected downside to using inline-able functions and case statements to avoid malformed data parsing.
Writing the function in pl/pgsql prevents the inlining and stabilizes the query.
