amogh-jahagirdar commented on code in PR #6559: URL: https://github.com/apache/iceberg/pull/6559#discussion_r1161334713
########## core/src/main/java/org/apache/iceberg/view/ViewMetadataParser.java: ########## @@ -0,0 +1,213 @@ +/* + * 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.view; + +import com.fasterxml.jackson.core.JsonGenerator; +import com.fasterxml.jackson.databind.JsonNode; +import java.io.IOException; +import java.io.InputStream; +import java.io.OutputStream; +import java.io.OutputStreamWriter; +import java.nio.charset.StandardCharsets; +import java.util.Iterator; +import java.util.List; +import java.util.Map; +import org.apache.iceberg.Schema; +import org.apache.iceberg.SchemaParser; +import org.apache.iceberg.exceptions.RuntimeIOException; +import org.apache.iceberg.io.InputFile; +import org.apache.iceberg.io.OutputFile; +import org.apache.iceberg.relocated.com.google.common.base.Preconditions; +import org.apache.iceberg.relocated.com.google.common.collect.ImmutableList; +import org.apache.iceberg.relocated.com.google.common.collect.Lists; +import org.apache.iceberg.util.JsonUtil; +import org.apache.iceberg.util.PropertyUtil; + +class ViewMetadataParser { + + // visible for testing + static final String FORMAT_VERSION = "format-version"; + static final String LOCATION = "location"; + static final String CURRENT_VERSION_ID = "current-version-id"; + static final String VERSIONS = "versions"; + static final String VERSION_LOG = "version-log"; + static final String PROPERTIES = "properties"; + static final String SCHEMAS = "schemas"; + static final String CURRENT_SCHEMA_ID = "current-schema-id"; + + public static void overwrite(ViewMetadata metadata, OutputFile outputFile) { + internalWrite(metadata, outputFile, true); + } + + public static void write(ViewMetadata metadata, OutputFile outputFile) { + internalWrite(metadata, outputFile, false); + } + + public static void internalWrite( + ViewMetadata metadata, OutputFile outputFile, boolean overwrite) { + OutputStream stream = overwrite ? outputFile.createOrOverwrite() : outputFile.create(); + try (OutputStreamWriter writer = new OutputStreamWriter(stream, StandardCharsets.UTF_8)) { + JsonGenerator generator = JsonUtil.factory().createGenerator(writer); + generator.useDefaultPrettyPrinter(); + toJson(metadata, generator); + generator.flush(); + } catch (IOException e) { + throw new RuntimeIOException(e, "Failed to write json to file: %s", outputFile); + } + } + + public static void toJson(ViewMetadata metadata, JsonGenerator generator) throws IOException { + generator.writeStartObject(); + + generator.writeNumberField(FORMAT_VERSION, metadata.formatVersion()); + generator.writeStringField(LOCATION, metadata.location()); + + JsonUtil.writeStringMap(PROPERTIES, metadata.properties(), generator); + + if (metadata.schemas() != null && !metadata.schemas().isEmpty()) { + generator.writeNumberField(CURRENT_SCHEMA_ID, metadata.currentSchemaId()); + generator.writeArrayFieldStart(SCHEMAS); + for (Schema schema : metadata.schemas()) { + SchemaParser.toJson(schema, generator); + } + + generator.writeEndArray(); + } Review Comment: I found https://github.com/apache/iceberg/pull/3188#discussion_r748303084 this thread on the original spec proposal, and then for view representation case there was https://github.com/apache/iceberg/pull/4925#discussion_r1015649887. So based on these two I don't think it's required that it's optional? I think it's just a convenience to avoid an engine having to pass in a schema at the time of view creation. Based on the second link it seems there is some complexity related to aliasing but if we store the pre-aliased schema that should be sufficient, the post alias columns can be subsequently derived. Schema handling will probably be a focal point around the view spec so it's important we get this right as we try and conclude this implementation. Right now schemaID in `SQLViewRepresentation` is optional. Maybe we revisit this, and make schemaID at the version level, since I think all representations should have the same Iceberg schema. Would love to get others thoughts here. -- 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. 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