According to https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DDL#LanguageManualDDL-ShowFunctions the currently available functions can be listed like this:
If the user executes this command, they will get the correct list of functions, but they will also see this on the standard output:
If the user uses the
command then they will receive the exact same result (though through different codes). The only difference is that one can get all the function names with "SHOW FUNCTIONS;", while "SHOW FUNCTIONS LIKE;" returns an exception, so in this case the pattern is mandatory.
So there should be a decision if we still accept "SHOW FUNCTIONS" without the "LIKE". My suggestion is to accept it only if there is no pattern. so "SHOW FUNCTIONS;" is ok, without deprecation message, but "SHOW FUNCTIONS <pattern>" should throw an exception.
Whatever we decide, we should document it appropriately.
cc Kris Hahn