[TAJO-482] Implements listing functions and describing a specified function.

• Type: Sub-task
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 0.8.0
• Component/s: Function/UDF
• Assignee: Hyoungjun Kim
• Reporter: Hyoungjun Kim
• Created: 07/Jan/14 09:47
• Updated: 22/Jan/14 02:20
• Resolved: 22/Jan/14 02:20

Description

I propose function related commands in Tajo's shell. This command is similar to PostgreSQL but a little different.

• \df: list all functions
• \df <function name>: list all functions which have a specified name(PostgreSQL uses a pattern matching).

tajo> \df
                  List of functions
Name | Result data type | Argument data types | Type 
-----+------------------+---------------------+-------------
avg  | FLOAT8           | INT8                | AGGREGATION
sum  | INT8             | INT8                | AGGREGATION
sum  | INT4             | INT4                | AGGREGATION
sum  | FLOAT4           | FLOAT4              | AGGREGATION
...
(80 rows)

tajo> \df sum
                  List of functions
Name | Result data type | Argument data types | Type 
-----+------------------+---------------------+-------------
sum  | INT8             | INT8                | AGGREGATION
sum  | INT4             | INT4                | AGGREGATION
sum  | FLOAT4           | FLOAT4              | AGGREGATION

(3 rows)

Function: INT8 sum(expr INT8)
Description: The sum of a set of numbers.
Example: 
> select sum(*)

When describing a specified function
if all functions have same description, prints out first function description. Otherwise prints out all function.

tajo> \df to_char

                  List of functions
  Name  |  Result data type | Argument data types | Type 
--------+-------------------+---------------------+-------------
to_char | TEXT              | TIMETSTAMP, TEXT    | GENERAL
to_char | TEXT              | INT4                | GENERAL

(2 rows)

Function: TEXT to_char(timestamp TIMETSTAMP, pattern TEXT)
Description: convert time stamp to string.
Example: 
> select to_char(current_timestamp, 'HH12:MI:SS');
11:34:52

Function: TEXT to_char(pattern INT4)
Description: convert time stamp to string.
Example: 
> select to_char(25, '000');
025

Issue Links

• blocks: TAJO-512 (Umbrella) 0.8 Release Preparation