snleee commented on code in PR #10856: URL: https://github.com/apache/pinot/pull/10856#discussion_r1220317462
########## pinot-plugins/pinot-input-format/pinot-csv/src/main/java/org/apache/pinot/plugin/inputformat/csv/CSVDefaultHeaderUtil.java: ########## @@ -0,0 +1,195 @@ +/** + * 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.pinot.plugin.inputformat.csv; + +import java.io.BufferedReader; +import java.io.File; +import java.io.IOException; +import java.util.ArrayList; +import java.util.HashMap; +import java.util.Iterator; +import java.util.List; +import java.util.Map; +import org.apache.commons.csv.CSVFormat; +import org.apache.commons.csv.CSVParser; +import org.apache.commons.csv.CSVRecord; +import org.apache.commons.lang3.StringUtils; +import org.apache.commons.lang3.math.NumberUtils; +import org.apache.pinot.spi.data.readers.RecordReaderUtils; + + +public class CSVDefaultHeaderUtil { + + private CSVDefaultHeaderUtil() { + } + + private static final String DEFAULT_CSV_COLUMN_PREFIX = "col_"; + private static final int MAX_CSV_SAMPLE_ROWS = 100; + + static class ColumnValueAttributes { + private Type _dataType; + private int _length; + + enum Type { + STRING, NUMBER, ARRAY + } + + ColumnValueAttributes(Object value, Character multiValueDelimiter) { + _dataType = Type.STRING; + if (multiValueDelimiter != null && value.toString().contains(String.valueOf(multiValueDelimiter))) { + _dataType = Type.ARRAY; + return; + } else if (NumberUtils.isParsable(value.toString())) { + _dataType = Type.NUMBER; + } + _length = value.toString().length(); + } + + public Type getDataType() { + return _dataType; + } + + public int getLength() { + return _length; + } + } + + /** + * Detects the types for each column based on the row values. If any column is of a single type (e.g. number), except + * for the first row, then the first row is presumed to be a header. If the type of the column is assumed to + * be a string, the length of the strings within the body is the determining factor. Specifically, if all the rows + * except the first are the same length, it's a header. + * + * If no header is detected, then the header property within the CSVRecordReaderConfig will be set with the following + * e.g. {col_0, col_1, col_2, ..}. If a header is detected within the file, then the header property will not + * be set and will default to use the first row of the file. + * + * Motivation for this logic is taken from: https://github.com/python/cpython/blob/main/Lib/csv.py + * + * Returns the default header when no header is detected. If the header is detected, then returns null. + */ + public static String getDefaultHeader(File csvFile, CSVFormat format, Character delimiter, + Character multiValueDelimiter) + throws IOException { + // Assume there is no header and the default header based on number of columns. We need the default header or + // else the CSVRecordReader may not read the values correctly when there are columns with the same values. + int numColumns = 0; + int rowCounter = 0; + List<CSVRecord> records = new ArrayList<>(); + String[] originalHeader = format.getHeader(); + try (BufferedReader bufferedReader = RecordReaderUtils.getBufferedReader(csvFile)) { + format.withHeader(null); + CSVParser parser = format.parse(bufferedReader); + Iterator<CSVRecord> iterator = parser.iterator(); + while (iterator.hasNext() && rowCounter < MAX_CSV_SAMPLE_ROWS + 1) { + CSVRecord row = iterator.next(); + records.add(row); + int curNumColumns = row.size(); + if (curNumColumns > numColumns) { + numColumns = curNumColumns; + } + rowCounter++; + } + } + + if (records.size() == 0) { + throw new IllegalStateException("CSV file is empty. csvFile=" + csvFile.getAbsolutePath()); + } + + String[] defaultColumnNames = new String[numColumns]; + for (int i = 0; i < numColumns; i++) { + defaultColumnNames[i] = DEFAULT_CSV_COLUMN_PREFIX + i; + } + + HashMap<String, ColumnValueAttributes> csvHeaderAttributes = new HashMap<>(numColumns); + HashMap<String, ColumnValueAttributes> csvBodyAttributes = new HashMap<>(numColumns); + Iterator<CSVRecord> iterator = records.iterator(); + if (iterator.hasNext()) { Review Comment: good catch. updated. -- This is an automated message from the Apache Git Service. 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