Comment by zeroimpl
2 years ago
An immutable function cannot query a table because the table itself isn’t immutable. If your stable/immutable flags don’t match reality, the function can’t be inlined.
2 years ago
An immutable function cannot query a table because the table itself isn’t immutable. If your stable/immutable flags don’t match reality, the function can’t be inlined.
Details in sibling but I dug a bit deeper, new version used to_char, turns out that is STABLE and not IMMUTABLE so because the volatility didn't match the whole way down anymore it broke inlining.
I'm guessing switching the function that calls to_char to STABLE will fix the problem.
Makes sense. You mentioned index so I thought maybe you were were querying a table.
Would be nice if postgresql could tell you when the flags don’t match. I think anytime you deal with timestamps you can have problems since the expression may depend on the session’s time zone.