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From: paul-rogers <git@git.apache.org>
To: dev@drill.apache.org
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References: <git-pr-907-drill@git.apache.org>
In-Reply-To: <git-pr-907-drill@git.apache.org>
Subject: [GitHub] drill pull request #907: DRILL-5697: Improve performance of filter operator ...
Content-Type: text/plain
Message-Id: <20170818191758.1A45EDFDDD@git1-us-west.apache.org>
Date: Fri, 18 Aug 2017 19:17:58 +0000 (UTC)
archived-at: Fri, 18 Aug 2017 19:18:01 -0000

Github user paul-rogers commented on a diff in the pull request:

    https://github.com/apache/drill/pull/907#discussion_r134035728
  
    --- Diff: exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/StringFunctions.java ---
    @@ -85,23 +183,118 @@ public void eval() {
         @Output BitHolder out;
         @Workspace java.util.regex.Matcher matcher;
         @Workspace org.apache.drill.exec.expr.fn.impl.CharSequenceWrapper charSequenceWrapper;
    +    @Workspace org.apache.drill.exec.expr.fn.impl.RegexpUtil.sqlPatternInfo patternInfo;
     
         @Override
         public void setup() {
    -      matcher = java.util.regex.Pattern.compile(org.apache.drill.exec.expr.fn.impl.RegexpUtil.sqlToRegexLike( //
    +      patternInfo = org.apache.drill.exec.expr.fn.impl.RegexpUtil.sqlToRegexLike(
               org.apache.drill.exec.expr.fn.impl.StringFunctionHelpers.toStringFromUTF8(pattern.start,  pattern.end,  pattern.buffer),
    -          org.apache.drill.exec.expr.fn.impl.StringFunctionHelpers.toStringFromUTF8(escape.start,  escape.end,  escape.buffer))).matcher("");
    +          org.apache.drill.exec.expr.fn.impl.StringFunctionHelpers.toStringFromUTF8(escape.start,  escape.end,  escape.buffer));
           charSequenceWrapper = new org.apache.drill.exec.expr.fn.impl.CharSequenceWrapper();
    -      matcher.reset(charSequenceWrapper);
    +
    +      // Use java regex and compile pattern only if it is not a simple pattern.
    +      if (patternInfo.getPatternType() == org.apache.drill.exec.expr.fn.impl.RegexpUtil.sqlPatternType.NOT_SIMPLE) {
    +        java.lang.String javaPatternString = patternInfo.getJavaPatternString();
    +        matcher = java.util.regex.Pattern.compile(javaPatternString).matcher("");
    +        matcher.reset(charSequenceWrapper);
    +      }
         }
     
         @Override
         public void eval() {
           charSequenceWrapper.setBuffer(input.start, input.end, input.buffer);
           // Reusing same charSequenceWrapper, no need to pass it in.
           // This saves one method call since reset(CharSequence) calls reset()
    -      matcher.reset();
    -      out.value = matcher.matches()? 1:0;
    +
    +      // Not a simple case. Just use Java regex.
    +      if (patternInfo.getPatternType() == org.apache.drill.exec.expr.fn.impl.RegexpUtil.sqlPatternType.NOT_SIMPLE) {
    --- End diff --
    
    We are doing a switch (actually, chain of ifs) per value. This is a tight inner loop. Far better to simply generate an instance of the proper class and call a single method to do the work.


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