>Put another way, what kinds of messages are included in the ERROR
>level? When the wrong data type is supplied for a table column? When a
>value in an COPY statement would violate a unique constraint? If so,
>why should LOG be even below ERROR?
Check log_min_error_statement(enum) description given in postgres document[1] as :
Valid values are DEBUG5, DEBUG4, DEBUG3, DEBUG2, DEBUG1, INFO, NOTICE, WARNING, ERROR, LOG, FATAL, and PANIC. *The default is ERROR, which means statements causing errors, log messages, fatal errors, or panics will be logged*.
Regards,
Amul
1. postgres document : http://www.postgresql.org/docs/9.4/static/runtime-config-logging.html.