[HIVE-21896] SHOW FUNCTIONS / SHOW FUNCTIONS LIKE - clarify

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.1.1
• Fix Version/s: 4.0.0-alpha-1
• Component/s: Hive
• Labels: incompatibleChange todoc4.0
• Assignee: Miklos Gergely
• Reporter: Miklos Gergely
• Created: 19/Jun/19 20:24
• Updated: 17/Nov/22 08:50
• Resolved: 26/Jun/19 15:42

Description

According to https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DDL#LanguageManualDDL-ShowFunctions the currently available functions can be listed like this:

SHOW FUNCTIONS <pattern>;

If the user executes this command, they will get the correct list of functions, but they will also see this on the standard output:

SHOW FUNCTIONS is deprecated, please use SHOW FUNCTIONS LIKE instead.

If the user uses the

SHOW FUNCTIONS LIKE <pattern>;

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 krishahn