[IMPALA-7741] Functions nvl2(), decode(), nullif() not listed in _impala_builtins

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: Impala 3.0
• Component/s: Catalog
• Epic Color: ghx-label-4
• Assignee: Unassigned
• Reporter: Paul Rogers
• Created: 22/Oct/18 22:07
• Updated: 21/Dec/20 19:43

Description

The docs for SHOW FUNCTIONS says that we can use the following to list all built-in functions:

show functions in _impala_builtins like '*week*';

However several Impala functions are removed early in the FE planning process and thus do not appear in the FE's function table in ScalarBuiltins: nvl2(), decode(), and nullif(). For example:

show functions in _impala_builtins like '*decode**'
+-------------+------------------------------+-------------+---------------+
| return type | signature                    | binary type | is persistent |
+-------------+------------------------------+-------------+---------------+
| STRING      | base64decode(STRING)         | BUILTIN     | true          |
| STRING      | madlib_decode_vector(STRING) | BUILTIN     | true          |
+-------------+------------------------------+-------------+---------------+

However, since these three are perfectly valid functions, would have expected them to appear in the table. How they are processed internally is an implementation detail unimportant to the end user.

Issue Links

• is part of: IMPALA-7747 Clean up the Expression Rewriter