JackieTien97 commented on a change in pull request #821: [IOTDB-298]Last time-value query URL: https://github.com/apache/incubator-iotdb/pull/821#discussion_r380531833
########## File path: server/src/main/java/org/apache/iotdb/db/query/executor/LastQueryExecutor.java ########## @@ -0,0 +1,201 @@ +/* + * 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.iotdb.db.query.executor; + +import org.apache.iotdb.db.exception.StorageEngineException; +import org.apache.iotdb.db.exception.path.PathException; +import org.apache.iotdb.db.exception.query.QueryProcessException; +import org.apache.iotdb.db.metadata.MManager; +import org.apache.iotdb.db.metadata.MNode; +import org.apache.iotdb.db.qp.constant.SQLConstant; +import org.apache.iotdb.db.qp.physical.crud.AggregationPlan; +import org.apache.iotdb.db.qp.physical.crud.LastQueryPlan; +import org.apache.iotdb.db.query.aggregation.AggregateResult; +import org.apache.iotdb.db.query.context.QueryContext; +import org.apache.iotdb.db.query.control.QueryResourceManager; +import org.apache.iotdb.db.query.dataset.SingleDataSet; +import org.apache.iotdb.db.query.factory.AggreResultFactory; +import org.apache.iotdb.db.query.reader.series.IAggregateReader; +import org.apache.iotdb.db.query.reader.series.SeriesAggregateReader; +import org.apache.iotdb.tsfile.exception.cache.CacheException; +import org.apache.iotdb.tsfile.file.metadata.enums.TSDataType; +import org.apache.iotdb.tsfile.file.metadata.statistics.Statistics; +import org.apache.iotdb.tsfile.read.TimeValuePair; +import org.apache.iotdb.tsfile.read.common.BatchData; +import org.apache.iotdb.tsfile.read.common.Path; +import org.apache.iotdb.tsfile.read.common.RowRecord; +import org.apache.iotdb.tsfile.read.filter.basic.Filter; +import org.apache.iotdb.tsfile.read.query.dataset.QueryDataSet; +import org.apache.iotdb.tsfile.utils.TsPrimitiveType; +import org.omg.CORBA.TIMEOUT; + +import java.io.IOException; +import java.sql.Time; +import java.util.*; + +public class LastQueryExecutor { + private List<Path> selectedSeries; + private List<TSDataType> dataTypes; + + public LastQueryExecutor(LastQueryPlan lastQueryPlan) { + this.selectedSeries = lastQueryPlan.getPaths(); + this.dataTypes = lastQueryPlan.getDataTypes(); + } + + /** + * execute last function + * + * @param context query context + */ + public QueryDataSet execute(QueryContext context) + throws StorageEngineException, IOException, QueryProcessException { + + List<LastQueryResult> lastQueryResultList = new ArrayList<>(); + for (int i = 0; i < selectedSeries.size(); i++) { + LastQueryResult lastQueryResult = calculateLastPairForOneSeries(selectedSeries.get(i), dataTypes.get(i), context); + lastQueryResultList.add(lastQueryResult); + } + + RowRecord resultRecord = constructLastRowRecord(lastQueryResultList); + SingleDataSet dataSet = new SingleDataSet(selectedSeries, dataTypes); + dataSet.setRecord(resultRecord); + return dataSet; + } + + /** + * get aggregation result for one series + * + * @param context query context + * @return AggregateResult list + */ + private LastQueryResult calculateLastPairForOneSeries( + Path seriesPath, TSDataType tsDataType, + QueryContext context) + throws IOException, QueryProcessException, StorageEngineException { + LastQueryResult queryResult = new LastQueryResult(); + MNode node = null; + try { + node = MManager.getInstance().getNodeByPathFromCache(seriesPath.toString()); + } catch (PathException e) { + throw new QueryProcessException(e); + } catch (CacheException e) { + throw new QueryProcessException(e.getMessage()); + } + if (node.getCachedLast() != null) { + queryResult.setPairResult(node.getCachedLast()); + return queryResult; + } + + // construct series reader without value filter + Filter timeFilter = null; + IAggregateReader seriesReader = new SeriesAggregateReader( + seriesPath, tsDataType, context, QueryResourceManager.getInstance() + .getQueryDataSource(seriesPath, context, timeFilter), timeFilter, null); + + long maxTime = Long.MIN_VALUE; + while (seriesReader.hasNextChunk()) { + while (seriesReader.hasNextPage()) { + // cal by page data + while (seriesReader.hasNextOverlappedPage()) { + BatchData nextOverlappedPageData = seriesReader.nextOverlappedPage(); + int maxIndex = nextOverlappedPageData.length() - 1; + if (maxIndex < 0) { + continue; + } + long time = nextOverlappedPageData.getTimeByIndex(maxIndex); + if (time > maxTime) { + maxTime = time; + queryResult.setPairResult(maxTime, nextOverlappedPageData.getValueInTimestamp(time), tsDataType); + } + nextOverlappedPageData.resetBatchData(); + } + } + } Review comment: You can use the chunk and page statistics if possible. The code will be like as: ``` while (seriesReader.hasNextChunk()) { if (seriesReader.canUseCurrentChunkStatistics()) { if (seriesReader.currentChunkStatistics().getEndTime() > maxTime) { maxTime = seriesReader.currentChunkStatistics().getEndTime(); queryResult.setPairResult(maxTime, seriesReader.currentChunkStatistics().getLastValue(), tsDataType); } seriesReader.skipCurrentChunk(); continue; } while (seriesReader.hasNextPage()) { if (seriesReader.canUseCurrentPageStatistics()) { if (seriesReader.currentPageStatistics().getEndTime() > maxTime) { maxTime = seriesReader.currentPageStatistics().getEndTime(); queryResult.setPairResult(maxTime, seriesReader.currentPageStatistics().getLastValue(), tsDataType); } seriesReader.skipCurrentPage(); continue; } // cal by page data while (seriesReader.hasNextOverlappedPage()) { BatchData nextOverlappedPageData = seriesReader.nextOverlappedPage(); int maxIndex = nextOverlappedPageData.length() - 1; if (maxIndex < 0) { continue; } long time = nextOverlappedPageData.getTimeByIndex(maxIndex); if (time > maxTime) { maxTime = time; queryResult.setPairResult(maxTime, nextOverlappedPageData.getValueInTimestamp(time), tsDataType); } nextOverlappedPageData.resetBatchData(); } } } ``` ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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