4a8c9e29bc
## What changes were proposed in this pull request?
This PR proposes to enhance the documentation for `trim` functions in the function description session.
- Add more `usage`, `arguments` and `examples` for the trim function
- Adjust space in the `usage` session
After the changes, the trim function documentation will look like this:
- `trim`
```trim(str) - Removes the leading and trailing space characters from str.
trim(BOTH trimStr FROM str) - Remove the leading and trailing trimStr characters from str
trim(LEADING trimStr FROM str) - Remove the leading trimStr characters from str
trim(TRAILING trimStr FROM str) - Remove the trailing trimStr characters from str
Arguments:
str - a string expression
trimStr - the trim string characters to trim, the default value is a single space
BOTH, FROM - these are keywords to specify trimming string characters from both ends of the string
LEADING, FROM - these are keywords to specify trimming string characters from the left end of the string
TRAILING, FROM - these are keywords to specify trimming string characters from the right end of the string
Examples:
> SELECT trim(' SparkSQL ');
SparkSQL
> SELECT trim('SL', 'SSparkSQLS');
parkSQ
> SELECT trim(BOTH 'SL' FROM 'SSparkSQLS');
parkSQ
> SELECT trim(LEADING 'SL' FROM 'SSparkSQLS');
parkSQLS
> SELECT trim(TRAILING 'SL' FROM 'SSparkSQLS');
SSparkSQ
```
- `ltrim`
```ltrim
ltrim(str) - Removes the leading space characters from str.
ltrim(trimStr, str) - Removes the leading string contains the characters from the trim string
Arguments:
str - a string expression
trimStr - the trim string characters to trim, the default value is a single space
Examples:
> SELECT ltrim(' SparkSQL ');
SparkSQL
> SELECT ltrim('Sp', 'SSparkSQLS');
arkSQLS
```
- `rtrim`
```rtrim
rtrim(str) - Removes the trailing space characters from str.
rtrim(trimStr, str) - Removes the trailing string which contains the characters from the trim string from the str
Arguments:
str - a string expression
trimStr - the trim string characters to trim, the default value is a single space
Examples:
> SELECT rtrim(' SparkSQL ');
SparkSQL
> SELECT rtrim('LQSa', 'SSparkSQLS');
SSpark
```
This is the trim characters function jira: [trim function](https://issues.apache.org/jira/browse/SPARK-14878)
## How was this patch tested?
Manually tested
```
spark-sql> describe function extended trim;
17/09/22 17:03:04 INFO CodeGenerator: Code generated in 153.026533 ms
Function: trim
Class: org.apache.spark.sql.catalyst.expressions.StringTrim
Usage:
trim(str) - Removes the leading and trailing space characters from `str`.
trim(BOTH trimStr FROM str) - Remove the leading and trailing `trimStr` characters from `str`
trim(LEADING trimStr FROM str) - Remove the leading `trimStr` characters from `str`
trim(TRAILING trimStr FROM str) - Remove the trailing `trimStr` characters from `str`
Extended Usage:
Arguments:
* str - a string expression
* trimStr - the trim string characters to trim, the default value is a single space
* BOTH, FROM - these are keywords to specify trimming string characters from both ends of
the string
* LEADING, FROM - these are keywords to specify trimming string characters from the left
end of the string
* TRAILING, FROM - these are keywords to specify trimming string characters from the right
end of the string
Examples:
> SELECT trim(' SparkSQL ');
SparkSQL
> SELECT trim('SL', 'SSparkSQLS');
parkSQ
> SELECT trim(BOTH 'SL' FROM 'SSparkSQLS');
parkSQ
> SELECT trim(LEADING 'SL' FROM 'SSparkSQLS');
parkSQLS
> SELECT trim(TRAILING 'SL' FROM 'SSparkSQLS');
SSparkSQ
```
```
spark-sql> describe function extended ltrim;
Function: ltrim
Class: org.apache.spark.sql.catalyst.expressions.StringTrimLeft
Usage:
ltrim(str) - Removes the leading space characters from `str`.
ltrim(trimStr, str) - Removes the leading string contains the characters from the trim string
Extended Usage:
Arguments:
* str - a string expression
* trimStr - the trim string characters to trim, the default value is a single space
Examples:
> SELECT ltrim(' SparkSQL ');
SparkSQL
> SELECT ltrim('Sp', 'SSparkSQLS');
arkSQLS
```
```
spark-sql> describe function extended rtrim;
Function: rtrim
Class: org.apache.spark.sql.catalyst.expressions.StringTrimRight
Usage:
rtrim(str) - Removes the trailing space characters from `str`.
rtrim(trimStr, str) - Removes the trailing string which contains the characters from the trim string from the `str`
Extended Usage:
Arguments:
* str - a string expression
* trimStr - the trim string characters to trim, the default value is a single space
Examples:
> SELECT rtrim(' SparkSQL ');
SparkSQL
> SELECT rtrim('LQSa', 'SSparkSQLS');
SSpark
```
Author: Kevin Yu <qyu@us.ibm.com>
Closes #19329 from kevinyu98/spark-14878-5.
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|---|---|---|
| .. | ||
| catalyst | ||
| core | ||
| hive | ||
| hive-thriftserver | ||
| create-docs.sh | ||
| gen-sql-markdown.py | ||
| mkdocs.yml | ||
| README.md | ||
Spark SQL
This module provides support for executing relational queries expressed in either SQL or the DataFrame/Dataset API.
Spark SQL is broken up into four subprojects:
- Catalyst (sql/catalyst) - An implementation-agnostic framework for manipulating trees of relational operators and expressions.
- Execution (sql/core) - A query planner / execution engine for translating Catalyst's logical query plans into Spark RDDs. This component also includes a new public interface, SQLContext, that allows users to execute SQL or LINQ statements against existing RDDs and Parquet files.
- Hive Support (sql/hive) - Includes an extension of SQLContext called HiveContext that allows users to write queries using a subset of HiveQL and access data from a Hive Metastore using Hive SerDes. There are also wrappers that allows users to run queries that include Hive UDFs, UDAFs, and UDTFs.
- HiveServer and CLI support (sql/hive-thriftserver) - Includes support for the SQL CLI (bin/spark-sql) and a HiveServer2 (for JDBC/ODBC) compatible server.
Running sql/create-docs.sh generates SQL documentation for built-in functions under sql/site.