Re: [PR] [SPARK-59063][SQL] Use a byte-length guard in LikeSimplification for 'prefix%suffix' [spark]

["uros-b (via GitHub)" <gi...@apache.org>]

uros-b commented on code in PR #58362:
URL: https://github.com/apache/spark/pull/58362#discussion_r3890866686


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sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/expressions.scala:
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@@ -830,11 +830,13 @@ object LikeSimplification extends Rule[LogicalPlan] with PredicateHelper {
         case endsWith(postfix) =>
           Some(EndsWith(input, Literal.create(postfix, input.dataType)))
         // 'a%a' pattern is basically same with 'a%' && '%a'.
-        // However, the additional `Length` condition is required to prevent 'a' match 'a%a'.
+        // However, the additional length condition is required to prevent 'a' match 'a%a'.
+        // Since StartsWith/EndsWith already pin the prefix and suffix at code-point boundaries,
+        // a byte-length guard (OctetLength, O(1)) is equivalent to a char-length guard and cheaper.
         case startsAndEndsWith(prefix, postfix) =>
-          Some(And(GreaterThanOrEqual(Length(input),
-            Literal.create(prefix.codePointCount(0, prefix.length)
-              + postfix.codePointCount(0, postfix.length))),
+          Some(And(GreaterThanOrEqual(OctetLength(input),

Review Comment:
   The main thing to be aware of here is that collation-aware anchors can match code points with different UTF-8 lengths.



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