Github user kkhatua commented on a diff in the pull request:
https://github.com/apache/drill/pull/907#discussion_r133859807
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/RegexpUtil.java
---
@@ -96,20 +145,46 @@ public static String sqlToRegexLike(
|| (nextChar == '%')
|| (nextChar == escapeChar)) {
javaPattern.append(nextChar);
+ simplePattern.append(nextChar);
i++;
} else {
throw invalidEscapeSequence(sqlPattern, i);
}
} else if (c == '_') {
+ // if we find _, it is not simple pattern, we are looking for only
%
+ notSimple = true;
javaPattern.append('.');
} else if (c == '%') {
+ if (i == 0) {
+ // % at the start could potentially be one of the simple cases
i.e. ENDS_WITH.
+ endsWith = true;
+ } else if (i == (len-1)) {
+ // % at the end could potentially be one of the simple cases
i.e. STARTS_WITH
+ startsWith = true;
+ } else {
+ // If we find % anywhere other than start or end, it is not a
simple case.
--- End diff --
Consider ABC%XYZ.
It might be worthwhile to decide whether to leverage a pattern or fall back
to Java's Regex util based on the number of occurrences of '%' as a criteria.
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