Jackie-Jiang commented on a change in pull request #6383: URL: https://github.com/apache/incubator-pinot/pull/6383#discussion_r549547785
########## File path: pinot-core/src/main/java/org/apache/pinot/core/operator/transform/function/LookupTransformFunction.java ########## @@ -0,0 +1,290 @@ +/** + * 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.core.operator.transform.function; + +import java.util.Arrays; +import java.util.List; +import java.util.Map; +import java.util.ArrayList; +import com.google.common.base.Preconditions; +import org.apache.commons.lang3.ArrayUtils; +import org.apache.pinot.core.common.DataSource; +import org.apache.pinot.core.data.manager.offline.DimensionTableDataManager; +import org.apache.pinot.core.operator.blocks.ProjectionBlock; +import org.apache.pinot.core.operator.transform.TransformResultMetadata; +import org.apache.pinot.spi.data.FieldSpec; +import org.apache.pinot.spi.data.readers.GenericRow; +import org.apache.pinot.spi.data.readers.PrimaryKey; + + +/** + * LOOKUP function takes 4 or more arguments: + * <ul> + * <li><b>TableName:</b> name of the dimension table which will be used</li> + * <li><b>ColumnName:</b> column name from the dimension table to look up</li> + * <li><b>JoinKey:</b> primary key column name for the dimension table. Note: Only primary key[s] are supported for JoinKey</li> + * <li><b>JoinValue:</b> primary key value</li> + * ...<br> + * *[If the dimension table has more then one primary keys (composite pk)] + * <li><b>JoinKey2</b></li> + * <li><b>JoinValue2</b></li> + * ... + * </ul> + * <br> + * Example: + * <pre>{@code SELECT + * baseballStats.playerName, + * baseballStats.teamID, + * LOOKUP('dimBaseballTeams', 'teamName', 'teamID', baseballStats.teamID) + * FROM + * baseballStats + * LIMIT 10}</pre> + * <br> + * Above example joins the dimension table 'baseballTeams' into regular table 'baseballStats' on 'teamID' key. + * Lookup function returns the value of the column 'teamName'. + */ +public class LookupTransformFunction extends BaseTransformFunction { + public static final String FUNCTION_NAME = "lookUp"; + private static final String TABLE_NAME_SUFFIX = "_OFFLINE"; + + // Lookup parameters + private String _dimTableName; + private String _dimColumnName; + private final List<String> _joinKeys = new ArrayList<>(); + private final List<FieldSpec> _joinValueFieldSpecs = new ArrayList<>(); + private final List<TransformFunction> _joinValueFunctions = new ArrayList<>(); + + private DimensionTableDataManager _dataManager; + private FieldSpec _lookupColumnFieldSpec; + + @Override + public String getName() { + return FUNCTION_NAME; + } + + @Override + public void init(List<TransformFunction> arguments, Map<String, DataSource> dataSourceMap) { + // Check that there are correct number of arguments + Preconditions + .checkArgument(arguments.size() >= 4, "At least 4 arguments are required for LOOKUP transform function"); + Preconditions + .checkArgument(arguments.size() % 2 == 0, "Should have the same number of JoinKey and JoinValue arguments"); + + TransformFunction dimTableNameFunction = arguments.get(0); + Preconditions.checkArgument(dimTableNameFunction instanceof LiteralTransformFunction, + "First argument must be a literal(string) representing the dimension table name"); + _dimTableName = ((LiteralTransformFunction) dimTableNameFunction).getLiteral(); + + TransformFunction dimColumnFunction = arguments.get(1); + Preconditions.checkArgument(dimColumnFunction instanceof LiteralTransformFunction, + "Second argument must be a literal(string) representing the column name from dimension table to lookup"); + _dimColumnName = ((LiteralTransformFunction) dimColumnFunction).getLiteral(); + + List<TransformFunction> joinArguments = arguments.subList(2, arguments.size()); + for (int i = 0; i < joinArguments.size() / 2; i++) { Review comment: The for loop will keep calling `joinArguments.size()` for each iteration ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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