MaxGekk commented on a change in pull request #27497:
[SPARK-30245][SQL][FOLLOWUP] Improve regex expression when pattern not changed
URL: https://github.com/apache/spark/pull/27497#discussion_r376724195
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/regexpExpressions.scala
##########
@@ -54,9 +54,20 @@ trait StringRegexExpression extends Expression
Pattern.compile(escape(str))
}
+ var lastPatternStr: String = null
+ var compiledPattern: Pattern = null
+
def nullSafeMatch(input1: Any, input2: Any): Any = {
- val s = input2.asInstanceOf[UTF8String].toString
- val regex = if (cache == null) compile(s) else cache
+ val patternStr = input2.asInstanceOf[UTF8String].toString
+ val regex = if (cache == null) {
+ if (!(patternStr).equals(lastPatternStr)) {
Review comment:
Benefits of this optimization depend on how patterns are distributed in a
column. For example, if we have:
| string | pattern|
|-|-|
|s1|pattern1|
|s2|pattern2|
|s3|pattern1|
|s4|pattern2|
in that case, this optimization can lead to slowdown.
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