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new f96486b [SPARK-28808][DOCS][SQL] Document SHOW FUNCTIONS in SQL
Reference
f96486b is described below
commit f96486b4aaba36a0f843c8a52801c305b0fa2b16
Author: Dilip Biswal <dbis...@us.ibm.com>
AuthorDate: Wed Sep 4 11:47:10 2019 -0700
[SPARK-28808][DOCS][SQL] Document SHOW FUNCTIONS in SQL Reference
### What changes were proposed in this pull request?
Document SHOW FUNCTIONS statement in SQL Reference Guide.
### Why are the changes needed?
Currently Spark lacks documentation on the supported SQL constructs causing
confusion among users who sometimes have to look at the code to understand
the
usage. This is aimed at addressing this issue.
### Does this PR introduce any user-facing change?
Yes.
**Before:**
There was no documentation for this.
**After.**
<img width="589" alt="Screen Shot 2019-09-04 at 11 41 44 AM"
src="https://user-images.githubusercontent.com/11567269/64281911-0fe79000-cf09-11e9-955f-21b44590707c.png";>
<img width="572" alt="Screen Shot 2019-09-04 at 11 41 54 AM"
src="https://user-images.githubusercontent.com/11567269/64281916-12e28080-cf09-11e9-9187-688c2c751559.png";>
### How was this patch tested?
Tested using jykyll build --serve
Closes #25539 from dilipbiswal/ref-doc-show-functions.
Lead-authored-by: Dilip Biswal <dbis...@us.ibm.com>
Co-authored-by: Xiao Li <gatorsm...@gmail.com>
Signed-off-by: Xiao Li <gatorsm...@gmail.com>
---
docs/sql-ref-syntax-aux-describe-function.md | 2 +-
docs/sql-ref-syntax-aux-show-functions.md | 119 ++++++++++++++++++++++++++-
2 files changed, 119 insertions(+), 2 deletions(-)
diff --git a/docs/sql-ref-syntax-aux-describe-function.md
b/docs/sql-ref-syntax-aux-describe-function.md
index 1c50708..d3dc192 100644
--- a/docs/sql-ref-syntax-aux-describe-function.md
+++ b/docs/sql-ref-syntax-aux-describe-function.md
@@ -34,7 +34,7 @@ metadata information is returned along with the extended
usage information.
<dl>
<dt><code><em>function_name</em></code></dt>
<dd>
- Specifies a name of an existing function in the syetem. The function name
may be
+ Specifies a name of an existing function in the system. The function name
may be
optionally qualified with a database name. If `function_name` is qualified
with
a database then the function is resolved from the user specified database,
otherwise
it is resolved from the current database.<br><br>
diff --git a/docs/sql-ref-syntax-aux-show-functions.md
b/docs/sql-ref-syntax-aux-show-functions.md
index ae689fd..db02607 100644
--- a/docs/sql-ref-syntax-aux-show-functions.md
+++ b/docs/sql-ref-syntax-aux-show-functions.md
@@ -19,4 +19,121 @@ license: |
limitations under the License.
---
-**This page is under construction**
+### Description
+Returns the list of functions after applying an optional regex pattern.
+Given number of functions supported by Spark is quite large, this statement
+in conjuction with [describe
function](sql-ref-syntax-aux-describe-function.html)
+may be used to quickly find the function and understand its usage. The `LIKE`
+clause is optional and supported only for compatibility with other systems.
+
+### Syntax
+{% highlight sql %}
+SHOW [ function_kind ] FUNCTIONS ([LIKE] function_name | regex_pattern)
+{% endhighlight %}
+
+### Parameters
+<dl>
+ <dt><code><em>function_kind</em></code></dt>
+ <dd>
+ Specifies the name space of the function to be searched upon. The valid
name spaces are :
+ <ul>
+ <li><b>USER</b> - Looks up the function(s) among the user defined
functions.</li>
+ <li><b>SYSTEM</b> - Looks up the function(s) among the system defined
functions.</li>
+ <li><b>ALL</b> - Looks up the function(s) among both user and system
defined functions.</li>
+ </ul>
+ </dd>
+ <dt><code><em>function_name</em></code></dt>
+ <dd>
+ Specifies a name of an existing function in the system. The function name
may be
+ optionally qualified with a database name. If `function_name` is qualified
with
+ a database then the function is resolved from the user specified database,
otherwise
+ it is resolved from the current database.<br><br>
+ <b>Syntax:</b>
+ <code>
+ [database_name.]function_name
+ </code>
+ </dd>
+ <dt><code><em>regex_pattern</em></code></dt>
+ <dd>
+ Specifies a regular expression pattern that is used to limit the results
of the
+ statement.
+ <ul>
+ <li>Only `*` and `|` are allowed as wildcard pattern.</li>
+ <li>Excluding `*` and `|` the remaining pattern follows the regex
semantics.</li>
+ <li>The leading and trailing blanks are trimmed in the input pattern
before processing.</li>
+ </ul>
+ </dd>
+</dl>
+
+### Examples
+{% highlight sql %}
+-- List a system function `trim` by searching both user defined and system
+-- defined functions.
+SHOW FUNCTIONS trim;
+ +--------+
+ |function|
+ +--------+
+ |trim |
+ +--------+
+
+-- List a system function `concat` by searching system defined functions.
+SHOW SYSTEM FUNCTIONS concat;
+ +--------+
+ |function|
+ +--------+
+ |concat |
+ +--------+
+
+-- List a qualified function `max` from database `salesdb`.
+SHOW SYSTEM FUNCTIONS salesdb.max;
+ +--------+
+ |function|
+ +--------+
+ |max |
+ +--------+
+
+-- List all functions starting with `t`
+SHOW FUNCTIONS LIKE 't*';
+ +-----------------+
+ |function |
+ +-----------------+
+ |tan |
+ |tanh |
+ |timestamp |
+ |tinyint |
+ |to_csv |
+ |to_date |
+ |to_json |
+ |to_timestamp |
+ |to_unix_timestamp|
+ |to_utc_timestamp |
+ |transform |
+ |transform_keys |
+ |transform_values |
+ |translate |
+ |trim |
+ |trunc |
+ +-----------------+
+
+-- List all functions starting with `yea` or `windo`
+SHOW FUNCTIONS LIKE 'yea*|windo*';
+ +--------+
+ |function|
+ +--------+
+ |window |
+ |year |
+ +--------+
+
+-- Use normal regex pattern to list function names that has 4 characters
+-- with `t` as the starting character.
+SHOW FUNCTIONS LIKE 't[a-z][a-z][a-z]';
+ +--------+
+ |function|
+ +--------+
+ |tanh |
+ |trim |
+ +--------+
+{% endhighlight %}
+
+### Related statements
+- [DESCRIBE FUNCTION](sql-ref-syntax-aux-describe-function.html)
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