Github user ppadma commented on a diff in the pull request: https://github.com/apache/drill/pull/1001#discussion_r146392275 --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/SqlPatternContainsMatcher.java --- @@ -17,37 +17,166 @@ */ package org.apache.drill.exec.expr.fn.impl; -public class SqlPatternContainsMatcher implements SqlPatternMatcher { +public final class SqlPatternContainsMatcher implements SqlPatternMatcher { final String patternString; CharSequence charSequenceWrapper; final int patternLength; + final MatcherFcn matcherFcn; public SqlPatternContainsMatcher(String patternString, CharSequence charSequenceWrapper) { - this.patternString = patternString; + this.patternString = patternString; this.charSequenceWrapper = charSequenceWrapper; - patternLength = patternString.length(); + patternLength = patternString.length(); + + // The idea is to write loops with simple condition checks to allow the Java Hotspot achieve + // better optimizations (especially vectorization) + if (patternLength == 1) { + matcherFcn = new Matcher1(); --- End diff -- I am not sure if it is a good idea to write special case code for each pattern length. It is not easy to maintain. Can you please give more details how this is improving performance ? Are we getting better performance for patternLength 1 or 2 or 3 or N or all ? If so, how much and why ?
---