the-other-tim-brown commented on code in PR #669: URL: https://github.com/apache/incubator-xtable/pull/669#discussion_r2040718628
########## xtable-core/src/main/java/org/apache/xtable/parquet/ParquetSchemaExtractor.java: ########## @@ -0,0 +1,535 @@ +/* + * 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.xtable.parquet; + +import java.util.HashMap; +import java.util.Map; +import java.util.List; +import java.util.ArrayList; + +import org.apache.xtable.schema.SchemaUtils; +import org.apache.xtable.exception.SchemaExtractorException; + +import java.util.Collections; +import java.util.Optional; + +import lombok.AccessLevel; +import lombok.NoArgsConstructor; + +import java.util.Arrays; +import java.util.Collections; +import java.util.function.Function; +import java.util.stream.Collectors; + +import org.apache.xtable.hudi.idtracking.models.IdMapping; +import org.apache.avro.Schema; +import org.apache.parquet.schema.GroupType; +import org.apache.parquet.schema.LogicalTypeAnnotation; +import org.apache.parquet.schema.MessageType; +import org.apache.parquet.schema.PrimitiveType; +import org.apache.parquet.schema.Type; +import org.apache.xtable.collectors.CustomCollectors; +import org.apache.xtable.exception.UnsupportedSchemaTypeException; +import org.apache.xtable.model.schema.InternalField; +import org.apache.parquet.schema.Type.Repetition; +import org.apache.xtable.model.schema.InternalSchema; +import org.apache.xtable.model.schema.InternalType; +import org.apache.parquet.schema.Type.ID; +import org.apache.parquet.schema.OriginalType; +import org.apache.parquet.schema.PrimitiveType.PrimitiveTypeName; +import org.apache.parquet.schema.Types; +import org.apache.parquet.column.ColumnDescriptor; + + +/** + * Class that converts parquet Schema {@link Schema} to Canonical Schema {@link InternalSchema} and + * vice-versa. This conversion is fully reversible and there is a strict 1 to 1 mapping between + * parquet data types and canonical data types. + */ +@NoArgsConstructor(access = AccessLevel.PRIVATE) +public class ParquetSchemaExtractor { + // parquet only supports string keys in maps + private static final InternalField MAP_KEY_FIELD = + InternalField.builder() + .name(InternalField.Constants.MAP_KEY_FIELD_NAME) + .schema( + InternalSchema.builder() + .name("map_key") + .dataType(InternalType.STRING) + .isNullable(false) + .build()) + .defaultValue("") + .build(); + private static final ParquetSchemaExtractor INSTANCE = new ParquetSchemaExtractor(); + private static final String ELEMENT = "element"; + private static final String KEY = "key"; + private static final String VALUE = "value"; + + public static ParquetSchemaExtractor getInstance() { + return INSTANCE; + } + + private static boolean groupTypeIsNullable(Type schema) { + return schema.getRepetition() == Repetition.REQUIRED ? false : true; + } + + private static boolean groupTypeContainsNull(Type schema) { + if (!schema.isPrimitive()) { + for (Type field : schema.asGroupType().getFields()) { + if (field/*.getLogicalTypeAnnotation().toOriginalType()*/ == null) { + return true; + } + } + } else { + if (schema.equals(null)) { + return true; + } + } + + return false; + } + + /* private static LogicalTypeAnnotation finalizeSchema(LogicalTypeAnnotation targetSchema, InternalSchema inputSchema) { + if (inputSchema.isNullable()) { + return targetSchema.union(null); // LogicalTypeAnnotation.unknownType() + } + return targetSchema; + }*/ + + /** + * Converts the parquet {@link Schema} to {@link InternalSchema}. + * + * @param schema The schema being converted + * @param parentPath If this schema is nested within another, this will be a dot separated string + * representing the path from the top most field to the current schema. + * @return a converted schema + */ + public InternalSchema toInternalSchema( + Type schema, String parentPath) { + // TODO - Does not handle recursion in parquet schema + InternalType newDataType = null; + Type.Repetition currentRepetition = null; + List<InternalField> subFields = new ArrayList<>(); + PrimitiveType primitiveType; + LogicalTypeAnnotation logicalType; + Map<InternalSchema.MetadataKey, Object> metadata = new HashMap<>(); + String elementName = schema.getName(); + if (schema.isPrimitive()) { + primitiveType = schema.asPrimitiveType(); + switch (primitiveType.getPrimitiveTypeName()) { + // PrimitiveTypes + case INT64: + logicalType = schema.getLogicalTypeAnnotation(); + if (logicalType instanceof LogicalTypeAnnotation.TimestampLogicalTypeAnnotation) { + LogicalTypeAnnotation.TimeUnit timeUnit = + ((LogicalTypeAnnotation.TimestampLogicalTypeAnnotation) logicalType).getUnit(); + if (timeUnit == LogicalTypeAnnotation.TimeUnit.MICROS) { + newDataType = InternalType.TIMESTAMP; + metadata.put( + InternalSchema.MetadataKey.TIMESTAMP_PRECISION, + InternalSchema.MetadataValue.MICROS); + } else if (timeUnit == LogicalTypeAnnotation.TimeUnit.MILLIS) { + newDataType = InternalType.TIMESTAMP_NTZ; Review Comment: You are currently using `TIMESTAMP_NTZ` without checking if it is actually this type. checking to see if it is a local timestamp vs adjusted to UTC is important so that other systems can read the value properly. -- This is an automated message from the Apache Git Service. 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