Jackie-Jiang commented on code in PR #15703: URL: https://github.com/apache/pinot/pull/15703#discussion_r2074221728
########## pinot-broker/src/main/java/org/apache/pinot/broker/requesthandler/EmptyResponseUtils.java: ########## @@ -0,0 +1,206 @@ +/** + * 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.broker.requesthandler; + +import com.google.common.base.Preconditions; +import java.util.Arrays; +import java.util.List; +import org.apache.calcite.rel.RelRoot; +import org.apache.calcite.rel.type.RelDataTypeField; +import org.apache.commons.lang3.tuple.Pair; +import org.apache.pinot.common.config.provider.TableCache; +import org.apache.pinot.common.request.context.ExpressionContext; +import org.apache.pinot.common.request.context.FilterContext; +import org.apache.pinot.common.response.BrokerResponse; +import org.apache.pinot.common.response.broker.ResultTable; +import org.apache.pinot.common.utils.DataSchema; +import org.apache.pinot.common.utils.DataSchema.ColumnDataType; +import org.apache.pinot.core.query.aggregation.function.AggregationFunction; +import org.apache.pinot.core.query.aggregation.function.AggregationFunctionUtils; +import org.apache.pinot.core.query.request.context.QueryContext; +import org.apache.pinot.query.QueryEnvironment; +import org.apache.pinot.query.planner.logical.RelToPlanNodeConverter; +import org.apache.pinot.spi.data.FieldSpec; +import org.apache.pinot.spi.data.Schema; + + +/// Similar to {@link org.apache.pinot.core.operator.blocks.results.ResultsBlockUtils} which handles empty results on +/// the server side, this class handles empty results on the broker side. +@SuppressWarnings({"rawtypes", "unchecked"}) +public class EmptyResponseUtils { + private EmptyResponseUtils() { + } + + // TODO: Use schema to fill the correct data types for empty results. + public static ResultTable buildEmptyResultTable(QueryContext queryContext) { + if (queryContext.getAggregationFunctions() == null) { + return buildEmptySelectionResultTable(queryContext); + } + if (queryContext.getGroupByExpressions() == null) { + return buildEmptyAggregationResultTable(queryContext); + } + return buildEmptyGroupByResultTable(queryContext); + } + + private static ResultTable buildEmptySelectionResultTable(QueryContext queryContext) { + List<ExpressionContext> selectExpressions = queryContext.getSelectExpressions(); + int numSelectExpressions = selectExpressions.size(); + String[] columnNames = new String[numSelectExpressions]; + for (int i = 0; i < numSelectExpressions; i++) { + columnNames[i] = selectExpressions.get(i).toString(); + } + ColumnDataType[] columnDataTypes = new ColumnDataType[numSelectExpressions]; + // NOTE: Use STRING column data type as default for selection query + Arrays.fill(columnDataTypes, ColumnDataType.STRING); + return new ResultTable(new DataSchema(columnNames, columnDataTypes), List.of()); + } + + private static ResultTable buildEmptyAggregationResultTable(QueryContext queryContext) { + List<Pair<AggregationFunction, FilterContext>> filteredAggregationFunctions = + queryContext.getFilteredAggregationFunctions(); + assert filteredAggregationFunctions != null; + int numAggregations = filteredAggregationFunctions.size(); + String[] columnNames = new String[numAggregations]; + ColumnDataType[] columnDataTypes = new ColumnDataType[numAggregations]; + Object[] row = new Object[numAggregations]; + for (int i = 0; i < numAggregations; i++) { + Pair<AggregationFunction, FilterContext> pair = filteredAggregationFunctions.get(i); + AggregationFunction aggregationFunction = pair.getLeft(); + columnNames[i] = AggregationFunctionUtils.getResultColumnName(aggregationFunction, pair.getRight()); + columnDataTypes[i] = aggregationFunction.getFinalResultColumnType(); + row[i] = aggregationFunction.extractFinalResult( + aggregationFunction.extractAggregationResult(aggregationFunction.createAggregationResultHolder())); + } + return new ResultTable(new DataSchema(columnNames, columnDataTypes), List.<Object[]>of(row)); + } + + private static ResultTable buildEmptyGroupByResultTable(QueryContext queryContext) { + List<Pair<AggregationFunction, FilterContext>> filteredAggregationFunctions = + queryContext.getFilteredAggregationFunctions(); + List<ExpressionContext> groupByExpressions = queryContext.getGroupByExpressions(); + assert filteredAggregationFunctions != null && groupByExpressions != null; + int numColumns = groupByExpressions.size() + filteredAggregationFunctions.size(); + String[] columnNames = new String[numColumns]; + ColumnDataType[] columnDataTypes = new ColumnDataType[numColumns]; + int index = 0; + for (ExpressionContext groupByExpression : groupByExpressions) { + columnNames[index] = groupByExpression.toString(); + // Use STRING column data type as default for group-by expressions + columnDataTypes[index] = ColumnDataType.STRING; + index++; + } + for (Pair<AggregationFunction, FilterContext> pair : filteredAggregationFunctions) { + AggregationFunction aggregationFunction = pair.getLeft(); + columnNames[index] = AggregationFunctionUtils.getResultColumnName(aggregationFunction, pair.getRight()); + columnDataTypes[index] = aggregationFunction.getFinalResultColumnType(); + index++; + } + return new ResultTable(new DataSchema(columnNames, columnDataTypes), List.of()); + } + + /** + * Tries to fill an {@link DataSchema} when no row has been returned. + * + * Response data schema can be inaccurate (all columns set to STRING) when all segments are pruned on broker or + * server. + * + * Priority is: + * - Types from multi-stage engine validation for the given query (if allowed). + * - Types from schema for the given table (only applicable to identifiers). + * - Types from single-stage engine response (no action). + * + * Multi-stage engine schema will be available only if query compiles. + */ + public static void fillEmptyResponseSchema(boolean useMSE, BrokerResponse response, TableCache tableCache, + Schema schema, String database, String query) { + Preconditions.checkState(response.getNumRowsResultSet() == 0, "Cannot fill schema for non-empty response"); + + DataSchema dataSchema = response.getResultTable() != null ? response.getResultTable().getDataSchema() : null; + + List<RelDataTypeField> dataTypeFields = null; + // Turn on (with pinot.broker.use.mse.to.fill.empty.response.schema=true or query option + // useMSEToFillEmptyResponseSchema=true) only for clusters where no queries with huge IN clauses are expected + // (see https://github.com/apache/pinot/issues/15064) + if (useMSE) { + QueryEnvironment queryEnvironment = new QueryEnvironment(database, tableCache, null); + RelRoot root; + try (QueryEnvironment.CompiledQuery compiledQuery = queryEnvironment.compile(query)) { + root = compiledQuery.getRelRoot(); + } catch (Exception ignored) { + root = null; + } + if (root != null && root.validatedRowType != null) { + dataTypeFields = root.validatedRowType.getFieldList(); + } + } + + if (dataSchema == null && dataTypeFields == null) { + // No schema available, nothing we can do + return; + } + + if (dataSchema == null || (dataTypeFields != null && dataSchema.size() != dataTypeFields.size())) { + // If data schema is not available or has different number of columns than the validated row type, we use the + // validated row type to populate the schema. + int numColumns = dataTypeFields.size(); + String[] columnNames = new String[numColumns]; + ColumnDataType[] columnDataTypes = new ColumnDataType[numColumns]; + for (int i = 0; i < numColumns; i++) { + RelDataTypeField dataTypeField = dataTypeFields.get(i); + columnNames[i] = dataTypeField.getName(); Review Comment: In most cases this code path shouldn't be triggered. It is only triggered when the column count doesn't match in SSE and MSE, and when user want to use MSE to fill the data schema. This method is only moved and no logic is changed -- 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. To unsubscribe, e-mail: commits-unsubscr...@pinot.apache.org 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
