aokolnychyi commented on a change in pull request #2403: URL: https://github.com/apache/iceberg/pull/2403#discussion_r606458455
########## File path: core/src/main/java/org/apache/iceberg/SerializedTable.java ########## @@ -0,0 +1,312 @@ +/* + * 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.iceberg; + +import java.io.Serializable; +import java.util.List; +import java.util.Map; +import org.apache.iceberg.encryption.EncryptionManager; +import org.apache.iceberg.hadoop.HadoopFileIO; +import org.apache.iceberg.hadoop.SerializedConfiguration; +import org.apache.iceberg.io.FileIO; +import org.apache.iceberg.io.LocationProvider; +import org.apache.iceberg.util.SerializableMap; + +/** + * A read-only serializable table implementation that can be sent to other nodes. + * <p> + * While this class captures the metadata file location that can be used to load the full table + * metadata, it also serializes directly things like properties, schema, spec, sort order + * to avoid reading the metadata file from other nodes to access frequently needed metadata. + * <p> + * <em>Note:</em> loading the full metadata from a large number of nodes can overwhelm the storage. + */ +public class SerializedTable implements Table, Serializable { + private final String name; + private final String location; + private final String metadataFileLocation; + private final Map<String, String> properties; + private final String schemaAsJson; + private final String specAsJson; + private final String sortOrderAsJson; + private final FileIO io; + private final EncryptionManager encryption; + private final LocationProvider locationProvider; + + private transient volatile Table lazyTable = null; + private transient volatile Schema lazySchema = null; + private transient volatile PartitionSpec lazySpec = null; + private transient volatile SortOrder lazySortOrder = null; + + public SerializedTable(Table table) { + this.name = table.name(); + this.location = table.location(); + this.metadataFileLocation = metadataFileLocation(table); + this.properties = SerializableMap.copyOf(table.properties()); + this.schemaAsJson = SchemaParser.toJson(table.schema()); + this.specAsJson = PartitionSpecParser.toJson(table.spec()); + this.sortOrderAsJson = SortOrderParser.toJson(table.sortOrder()); + this.io = fileIO(table); + this.encryption = table.encryption(); + this.locationProvider = table.locationProvider(); + } + + private String metadataFileLocation(Table table) { + if (table instanceof HasTableOperations) { + TableOperations ops = ((HasTableOperations) table).operations(); + return ops.current().metadataFileLocation(); + } else { + return null; + } + } + + private FileIO fileIO(Table table) { Review comment: Yeah, we would definitely need a more generic solution for `FileIO` implementations that depend on Hadoop conf. I tried to prototype that but it raised a number of questions. The last idea I had was something like this: ``` interface ConfigurableFileIO<T extends ConfigurableFileIO> extends FileIO, Configurable { T toSerializable(SerializedConfiguration serializedConf); default Object writeReplace() { // default the implementation to call `toSerializable` } } ``` It was clear this requires a separate PR and more thinking. That's why I propose to address that in a follow-up. -- 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: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
