Github user jodersky commented on a diff in the pull request:
https://github.com/apache/spark/pull/15398#discussion_r84143867
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/regexpExpressions.scala
---
@@ -68,7 +68,20 @@ trait StringRegexExpression extends
ImplicitCastInputTypes {
* Simple RegEx pattern matching function
*/
@ExpressionDescription(
- usage = "str _FUNC_ pattern - Returns true if str matches pattern and
false otherwise.")
+ usage = "str _FUNC_ pattern - Returns true if str matches pattern, " +
+ "null if any arguments are null, false otherwise.",
+ extended =
+ "The pattern is a string which is matched literally, with exception to
the " +
+ "following special symbols:\n\n" +
+ " _ matches any one character in the input (similar to . in posix "
+
+ "regular expressions)\n\n" +
+ " % matches zero ore more characters in the input (similar to .* in
" +
+ "posix regular expressions\n\n" +
+ "The default escape character is '\\'. If an escape character precedes
a special symbol or " +
+ "another escape character, the following character is matched
literally, otherwise the " +
+ "escape character is treated literally. I.e. '\\%' would match '%',
whereas '\\a' matches " +
+ "'\\a'.\n\n" +
--- End diff --
good idea
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