gianm commented on code in PR #19383: URL: https://github.com/apache/druid/pull/19383#discussion_r3171845858
########## processing/src/main/java/org/apache/druid/segment/PartialQueryableIndex.java: ########## @@ -0,0 +1,427 @@ +/* + * 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.druid.segment; + +import com.google.common.base.Supplier; +import com.google.common.base.Suppliers; +import com.google.common.collect.Maps; +import it.unimi.dsi.fastutil.objects.ObjectAVLTreeSet; +import org.apache.druid.collections.bitmap.BitmapFactory; +import org.apache.druid.error.DruidException; +import org.apache.druid.java.util.common.Intervals; +import org.apache.druid.java.util.common.io.smoosh.SmooshedFileMapper; +import org.apache.druid.query.OrderBy; +import org.apache.druid.segment.column.BaseColumnHolder; +import org.apache.druid.segment.column.ColumnCapabilities; +import org.apache.druid.segment.column.ColumnCapabilitiesImpl; +import org.apache.druid.segment.column.ColumnConfig; +import org.apache.druid.segment.column.ColumnDescriptor; +import org.apache.druid.segment.column.ColumnHolder; +import org.apache.druid.segment.data.Indexed; +import org.apache.druid.segment.data.ListIndexed; +import org.apache.druid.segment.file.PartialSegmentFileMapperV10; +import org.apache.druid.segment.file.SegmentFileMapper; +import org.apache.druid.segment.file.SegmentFileMetadata; +import org.apache.druid.segment.projections.AggregateProjectionSchema; +import org.apache.druid.segment.projections.BaseTableProjectionSchema; +import org.apache.druid.segment.projections.ConstantTimeColumn; +import org.apache.druid.segment.projections.ProjectionMetadata; +import org.apache.druid.segment.projections.Projections; +import org.apache.druid.segment.projections.QueryableProjection; +import org.joda.time.Interval; + +import javax.annotation.Nullable; +import java.io.IOException; +import java.nio.ByteBuffer; +import java.util.ArrayList; +import java.util.LinkedHashMap; +import java.util.LinkedHashSet; +import java.util.List; +import java.util.Map; +import java.util.SortedSet; +import java.util.concurrent.ConcurrentHashMap; +import java.util.stream.Collectors; + +/** + * A {@link QueryableIndex} that loads projection and base table columns on demand from a + * {@link PartialSegmentFileMapperV10}. Schema queries (column names, types, intervals, metadata) are answered from + * the {@link SegmentFileMetadata} alone without triggering any downloads. Column data is only downloaded when a column + * is accessed via {@link #getColumnHolder(String)} or {@link #getProjection(CursorBuildSpec)}. + * <p> + * Projection matching uses only metadata ({@link SegmentFileMetadata#getColumnDescriptors()} keys) to determine if + * a projection can satisfy a query, avoiding downloads of projection data that won't be used. + * + * @see PartialSegmentFileMapperV10 + */ +public class PartialQueryableIndex implements QueryableIndex +{ + private final Interval dataInterval; + private final int baseNumRows; + private final Indexed<String> availableDimensions; + private final List<String> columnNames; + private final BitmapFactory bitmapFactory; + private final PartialSegmentFileMapperV10 fileMapper; + private final SegmentFileMetadata metadata; + private final ColumnConfig columnConfig; + private final Metadata reconstructedMetadata; + private final List<OrderBy> ordering; + + // projection metadata for matching + private final SortedSet<AggregateProjectionMetadata> projections; + private final Map<String, AggregateProjectionMetadata> projectionsMap; + private final Map<String, ProjectionMetadata> projectionSpecs; + + // segment-internal file prefix for the base table projection, used to translate column names to descriptor keys + private final String baseProjectionPrefix; + + // base table columns, built at construction time. each entry's supplier defers both mapFile() and column + // deserialization until the column is actually accessed, so queries only trigger downloads for the specific + // columns they use. + private final Map<String, Supplier<BaseColumnHolder>> baseColumns; + + // projection columns, keyed by projection name. built on demand (per-projection) when the projection is matched. + // within each projection, per-column suppliers defer both mapFile() and deserialization. + private final ConcurrentHashMap<String, Map<String, Supplier<BaseColumnHolder>>> projectionColumnsByName = + new ConcurrentHashMap<>(); + + // lazy dimension handlers + private final Supplier<Map<String, DimensionHandler>> dimensionHandlers; + + public PartialQueryableIndex( + SegmentFileMetadata metadata, + PartialSegmentFileMapperV10 fileMapper, + ColumnConfig columnConfig + ) + { + this.metadata = metadata; + this.fileMapper = fileMapper; + this.columnConfig = columnConfig; + + // base table projection is always first + final ProjectionMetadata baseProjection = metadata.getProjections().get(0); + DruidException.conditionalDefensive( + Projections.BASE_TABLE_PROJECTION_NAME.equals(baseProjection.getSchema().getName()), + "Expected base table projection with name[%s], but got projection with name[%s] instead", + Projections.BASE_TABLE_PROJECTION_NAME, + baseProjection.getSchema().getName() + ); + final BaseTableProjectionSchema baseSchema = (BaseTableProjectionSchema) baseProjection.getSchema(); + this.baseNumRows = baseProjection.getNumRows(); + this.baseProjectionPrefix = Projections.getProjectionSegmentInternalFilePrefix(baseSchema); + this.dataInterval = Intervals.of(metadata.getInterval()); + this.bitmapFactory = metadata.getBitmapEncoding().getBitmapFactory(); + this.availableDimensions = new ListIndexed<>(baseSchema.getDimensionNames()); + + // build column names (dimensions first, then other columns, excluding __time) + final LinkedHashSet<String> dimsFirst = new LinkedHashSet<>(baseSchema.getDimensionNames()); + for (String columnName : baseSchema.getColumnNames()) { + if (!ColumnHolder.TIME_COLUMN_NAME.equals(columnName)) { + dimsFirst.add(columnName); + } + } + this.columnNames = List.copyOf(dimsFirst); + + // build aggregate projection metadata for matching + final List<AggregateProjectionMetadata> aggProjections = new ArrayList<>(); + this.projectionSpecs = new ConcurrentHashMap<>(); + boolean first = true; + for (ProjectionMetadata projectionSpec : metadata.getProjections()) { + if (first) { + first = false; + continue; + } + if (projectionSpec.getSchema() instanceof AggregateProjectionSchema) { + aggProjections.add( + new AggregateProjectionMetadata( + (AggregateProjectionSchema) projectionSpec.getSchema(), + projectionSpec.getNumRows() + ) + ); + projectionSpecs.put(projectionSpec.getSchema().getName(), projectionSpec); Review Comment: Some kind of acknowledgement would be good. Either a comment, or warning log, or defensive exception. Whichever one of those seems best. -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
