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https://issues.apache.org/jira/browse/DRILL-5899?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16243237#comment-16243237
]
ASF GitHub Bot commented on DRILL-5899:
---------------------------------------
Github user paul-rogers commented on a diff in the pull request:
https://github.com/apache/drill/pull/1015#discussion_r149552453
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/AbstractSqlPatternMatcher.java
---
@@ -0,0 +1,61 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.drill.exec.expr.fn.impl;
+
+import com.google.common.base.Charsets;
+import org.apache.drill.common.exceptions.UserException;
+import java.nio.ByteBuffer;
+import java.nio.CharBuffer;
+import java.nio.charset.CharacterCodingException;
+import java.nio.charset.CharsetEncoder;
+import static
org.apache.drill.exec.expr.fn.impl.StringFunctionHelpers.logger;
+
+// To get good performance for most commonly used pattern matches
--- End diff --
Javadoc?
```
/**
* This is a Javadoc comment and appears in generated documentation.
*/
// This is a plain comment and does not appear in documentation.
```
> Simple pattern matchers can work with DrillBuf directly
> -------------------------------------------------------
>
> Key: DRILL-5899
> URL: https://issues.apache.org/jira/browse/DRILL-5899
> Project: Apache Drill
> Issue Type: Improvement
> Components: Execution - Flow
> Reporter: Padma Penumarthy
> Assignee: Padma Penumarthy
> Priority: Critical
>
> For the 4 simple patterns we have i.e. startsWith, endsWith, contains and
> constant,, we do not need the overhead of charSequenceWrapper. We can work
> with DrillBuf directly. This will save us from doing isAscii check and UTF8
> decoding for each row.
> UTF-8 encoding ensures that no UTF-8 character is a prefix of any other valid
> character. So, instead of decoding varChar from each row we are processing,
> encode the patternString once during setup and do raw byte comparison.
> Instead of bounds checking and reading one byte at a time, we get the whole
> buffer in one shot and use that for comparison.
> This improved overall performance for filter operator by around 20%.
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