pg_hint_plan stops hint parsing on any error and will uses the hints
already parsed. Here are some typical errors.
Any syntactical errors or wrong hint names are reported as a syntax error.
These errors are reported in the server log with the message level specified
pg_hint_plan.debug_print is on and
Incorrect Object definitions
Incorrect object definitions result in silently ignoring the hints. This kind of error is reported as a "Not Used Hint" in the server logs.
Redundant or conflicting hints
The last hint is considered when redundant hints are defined or hints conflict with each other. This kind of error is reported as a duplicated hints.
Hint comments cannot be recursive. If detected, hint parsing is immediately stopped and all the hints already parsed are ignored.