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https://issues.apache.org/jira/browse/DRILL-3988?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16632180#comment-16632180
]
ASF GitHub Bot commented on DRILL-3988:
---------------------------------------
kkhatua opened a new pull request #1483: DRILL-3988: Expose Drill built-in
functions & UDFs in a system table
URL: https://github.com/apache/drill/pull/1483
This commit exposes available SQL functions in Drill and also detects UDFs
that have been dynamically loaded into Drill.
An example is shown below for 2 UDFs dynamically loaded into the cluster,
along side the existing built-in functions that come with Drill.
```
0: jdbc:drill:schema=sys> select source, count(*) as functionCount from
sys.functions group by source;
+-----------------------------------------+----------------+
| source | functionCount |
+-----------------------------------------+----------------+
| built-in | 2704 |
| simple-drill-function-1.0-SNAPSHOT.jar | 12 |
| drill-url-tools-1.0.jar | 1 |
+-----------------------------------------+----------------+
1 row selected (0.211 seconds)
```
The system table exposes information as shown. Since UDFs are lazily
initialized (i.e. only when a SQL query needs it), the `returnType` is not
available and listed as `n/a`.
Once the UDF is initialized, the `returnType` is also available.
The `random(FLOAT8-REQUIRED,FLOAT8-REQUIRED)` function is an example of a
lazily loaded UDF (see `returnType`).
The `url_parse(VARCHAR-REQUIRED)` function is an example of an initialized
UDF (see `returnType`).
Rest are built-in functions that meet the query's filter criteria.
```
0: jdbc:drill:schema=sys>select * from sys.functions where name like
'random' or `name` like '%url%';
+-------------+----------------------------------+-------------+-----------------------------------------+
| name | signature | returnType |
source |
+-------------+----------------------------------+-------------+-----------------------------------------+
| parse_url | VARCHAR-REQUIRED | LATE | built-in
|
| random | | FLOAT8 | built-in
|
| random | FLOAT8-REQUIRED,FLOAT8-REQUIRED | n/a |
simple-drill-function-1.0-SNAPSHOT.jar |
| url_decode | VARCHAR-REQUIRED | VARCHAR | built-in
|
| url_encode | VARCHAR-REQUIRED | VARCHAR | built-in
|
| url_parse | VARCHAR-REQUIRED | LATE |
drill-url-tools-1.0.jar |
+-------------+----------------------------------+-------------+-----------------------------------------+
6 rows selected (0.221 seconds)
```
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> Create a sys.functions table to expose available Drill functions
> ----------------------------------------------------------------
>
> Key: DRILL-3988
> URL: https://issues.apache.org/jira/browse/DRILL-3988
> Project: Apache Drill
> Issue Type: Sub-task
> Components: Metadata
> Reporter: Jacques Nadeau
> Assignee: Kunal Khatua
> Priority: Major
> Labels: newbie
> Fix For: 1.15.0
>
>
> Create a new sys.functions table that returns a list of all available
> functions.
> Key considerations:
> - one row per name or one per argument set. I'm inclined to latter so people
> can use queries to get to data.
> - we need to create a delineation between user functions and internal
> functions and only show user functions. 'CastInt' isn't something the user
> should be able to see (or run).
> - should we add a description annotation that could be included in the
> sys.functions table?
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