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Posted to dev@tajo.apache.org by "hyoungjunkim (JIRA)" <ji...@apache.org> on 2014/01/09 02:03:50 UTC
[jira] [Assigned] (TAJO-482) Implements listing functions and
describing a specified function.
[ https://issues.apache.org/jira/browse/TAJO-482?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
hyoungjunkim reassigned TAJO-482:
---------------------------------
Assignee: hyoungjunkim
> Implements listing functions and describing a specified function.
> -----------------------------------------------------------------
>
> Key: TAJO-482
> URL: https://issues.apache.org/jira/browse/TAJO-482
> Project: Tajo
> Issue Type: Sub-task
> Components: function/udf
> Reporter: hyoungjunkim
> Assignee: hyoungjunkim
> Priority: Minor
> Fix For: 0.8-incubating
>
>
> 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).
> {code}
> 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(*)
> {code}
> When describing a specified function
> if all functions have same description, prints out first function description. Otherwise prints out all function.
> {code}
> 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
> {code}
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