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https://issues.apache.org/jira/browse/DRILL-5498?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16016372#comment-16016372
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ASF GitHub Bot commented on DRILL-5498:
---------------------------------------
Github user sohami commented on a diff in the pull request:
https://github.com/apache/drill/pull/830#discussion_r117338017
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/store/easy/text/compliant/HeaderBuilder.java
---
@@ -0,0 +1,249 @@
+/*
+ * 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.store.easy.text.compliant;
+
+import java.nio.BufferOverflowException;
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+import com.google.common.base.Charsets;
+
+/**
+ * Text output that implements a header reader/parser.
+ * The caller parses out the characters of each header;
+ * this class assembles UTF-8 bytes into Unicode characters,
+ * fixes invalid characters (those not legal for SQL symbols),
+ * and maps duplicate names to unique names.
+ * <p>
+ * That is, this class is as permissive as possible with file
+ * headers to avoid spurious query failures for trivial reasons.
+ */
+
+// Note: this class uses Java heap strings and the usual Java
+// convenience classes. Since we do heavy Unicode string operations,
+// and read a single row, there is no good reason to try to use
+// value vectors and direct memory for this task.
+
+public class HeaderBuilder extends TextOutput {
+
+ /**
+ * Maximum Drill symbol length, as enforced for headers.
+ * @see <a
href="https://drill.apache.org/docs/lexical-structure/#identifier";>
+ * identifier documentation</a>
+ */
+ // TODO: Replace with the proper constant, if available
+ public static final int MAX_HEADER_LEN = 1024;
+
+ /**
+ * Exception that reports header errors. Is an unchecked exception
+ * to avoid cluttering the normal field reader interface.
+ */
+ public static class HeaderError extends RuntimeException {
+
+ private static final long serialVersionUID = 1L;
+
+ public HeaderError(String msg) {
+ super(msg);
+ }
+
+ public HeaderError(int colIndex, String msg) {
+ super("Column " + (colIndex + 1) + ": " + msg);
+ }
+
+ }
+
+ public List<String> headers = new ArrayList<>();
+ public ByteBuffer currentField = ByteBuffer.allocate(MAX_HEADER_LEN);
+
--- End diff --
`final` for both the parameters
> CSV text reader does not properly handle duplicate header names
> ---------------------------------------------------------------
>
> Key: DRILL-5498
> URL: https://issues.apache.org/jira/browse/DRILL-5498
> Project: Apache Drill
> Issue Type: Bug
> Affects Versions: 1.8.0
> Reporter: Paul Rogers
> Assignee: Paul Rogers
> Priority: Minor
>
> Consider the following CSV file:
> {code}
> h,h,h
> a,b,c
> d,e,f
> {code}
> Parse this with the CSV storage plugins to parse headers. The result:
> {code}
> 2 row(s):
> h
> c
> f
> {code}
> Expected a runtime error for the duplicate column names, or automatic
> "uniqification" of the names. Certainly did not expect the first two columns
> to be dropped.
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