maropu commented on a change in pull request #25001: [SPARK-28083][SQL] Support
LIKE ... ESCAPE syntax
URL: https://github.com/apache/spark/pull/25001#discussion_r308523852
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File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/regexpExpressions.scala
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@@ -83,33 +83,39 @@ abstract class StringRegexExpression extends
BinaryExpression
% matches zero or more characters in the input (similar to .* in
posix regular
expressions)
- The escape character is '\'. If an escape character precedes a
special symbol or another
- escape character, the following character is matched literally. It
is invalid to escape
- any other character.
-
Since Spark 2.0, string literals are unescaped in our SQL parser.
For example, in order
to match "\abc", the pattern should be "\\abc".
When SQL config 'spark.sql.parser.escapedStringLiterals' is enabled,
it fallbacks
to Spark 1.6 behavior regarding string literal parsing. For example,
if the config is
enabled, the pattern to match "\abc" should be "\abc".
+ * escape - a optional string. The default escape character is the '\' .
If an escape character
+ precedes a special symbol or another escape character, the following
character is matched
+ literally. It is invalid to escape any other character. You can
specify '' as escape
+ character so that disables the escape mechanism, which makes it
impossible to turn off
+ the special meaning of underscore and percent signs in the pattern.
Review comment:
I like the behivour, but we should wait for the other review's comment. cc:
@dongjoon-hyun @gatorsmile
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