yupeng9 commented on a change in pull request #6383: URL: https://github.com/apache/incubator-pinot/pull/6383#discussion_r549236949
########## File path: pinot-core/src/main/java/org/apache/pinot/core/operator/transform/function/LookupTransformFunction.java ########## @@ -0,0 +1,284 @@ +/** + * 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 take 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] is 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 playerName, teamID, lookup('baseballTeams', 'teamName', 'teamID', 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++) { + TransformFunction dimJoinKeyFunction = joinArguments.get((i*2)); + Preconditions.checkArgument(dimJoinKeyFunction instanceof LiteralTransformFunction, + "JoinKey argument must be a literal(string) representing the primary key for the dimension table"); + _joinKeys.add(((LiteralTransformFunction) dimJoinKeyFunction).getLiteral()); + + TransformFunction factJoinValueFunction = joinArguments.get((i*2)+1); + TransformResultMetadata factJoinValueFunctionResultMetadata = factJoinValueFunction.getResultMetadata(); + Preconditions.checkArgument(factJoinValueFunctionResultMetadata.isSingleValue(), + "JoinValue argument must be a single value expression"); + _joinValueFunctions.add(factJoinValueFunction); + } + + // Validate lookup table and relevant columns + _dataManager = DimensionTableDataManager.getInstanceByTableName(_dimTableName + TABLE_NAME_SUFFIX); + Preconditions.checkArgument(_dataManager != null, + String.format("Dimension table does not exist: %s", _dimTableName)); + + _lookupColumnFieldSpec = _dataManager.getColumnFieldSpec(_dimColumnName); + Preconditions.checkArgument(_lookupColumnFieldSpec != null, + String.format("Column does not exist in dimension table: %s:%s", _dimTableName, _dimColumnName)); + + for (String joinKey: _joinKeys) { + FieldSpec pkColumnSpec = _dataManager.getColumnFieldSpec(joinKey); + Preconditions.checkArgument(pkColumnSpec != null, Review comment: I meant checking the join keys are the same as the primary keys defined on a table. Assume a table has 2 columns of the primary key, then this lookup function shall take two join keys too, to ensure the same cardinality in the output. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@pinot.apache.org For additional commands, e-mail: commits-h...@pinot.apache.org
