org.apache.impala.infra.tableflattener.SchemaUtil.java Source code

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Here is the source code for org.apache.impala.infra.tableflattener.SchemaUtil.java

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// 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.impala.infra.tableflattener;

import com.google.common.base.Joiner;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableMap;
import org.apache.avro.Schema;
import org.apache.avro.Schema.Field;
import org.apache.avro.Schema.Type;
import org.apache.avro.generic.GenericRecord;
import org.codehaus.jackson.JsonNode;

import java.util.Map;

public class SchemaUtil {

    // Used to validate unions. This is a substitution map for comparison purposes.
    static final Map<Type, Type> BASE_TYPES = ImmutableMap.<Type, Type>builder().put(Type.STRING, Type.BYTES)
            .put(Type.FIXED, Type.BYTES).put(Type.DOUBLE, Type.INT).put(Type.FLOAT, Type.INT)
            .put(Type.LONG, Type.INT).build();

    static Field createField(String name, Type type) {
        return createField(name, type, null, null);
    }

    static Field createField(String name, Type type, String doc, JsonNode defaultValue) {
        return new Field(name, Schema.createUnion(Schema.create(Type.NULL), Schema.create(type)), doc,
                defaultValue);
    }

    static Field createField(String name, Schema schema) {
        return createField(name, schema, null, null);
    }

    static Field createField(String name, Schema schema, String doc, JsonNode defaultValue) {
        Preconditions.checkState(!schemaHasNesting(schema));
        if (schema.getType() == Type.UNION) {
            return new Field(name, Schema.createUnion(schema.getTypes()), doc, defaultValue);
        }
        return createField(name, schema.getType(), doc, defaultValue);
    }

    static boolean recordHasField(GenericRecord record, String fieldName) {
        return record.getSchema().getField(fieldName) != null;
    }

    static Schema reduceUnionToNonNull(Schema unionSchema) {
        Schema reducedSchema = null;
        Type reducedBaseType = null;
        for (Schema schema : unionSchema.getTypes()) {
            if (schema.getType() == Type.NULL)
                continue;
            String logicalType = schema.getProp("logicalType");
            Type baseType;
            if (logicalType == null) {
                baseType = BASE_TYPES.containsKey(schema.getType()) ? BASE_TYPES.get(schema.getType())
                        : schema.getType();
            } else {
                Preconditions.checkState(logicalType.equals("decimal"));
                baseType = Type.INT;
            }
            if (reducedBaseType == null) {
                reducedSchema = schema;
                reducedBaseType = baseType;
                continue;
            }
            if (reducedBaseType != baseType) {
                throw new RuntimeException(String.format("Union contains incompatible types: %s",
                        Joiner.on(" ,").join(unionSchema.getTypes())));
            }
        }
        if (reducedSchema == null) {
            throw new RuntimeException(String.format("Union schema contains no non-null types: %s",
                    Joiner.on(" ,").join(unionSchema.getTypes())));
        }
        return reducedSchema;
    }

    static boolean isNullable(Schema schema) {
        return schema.getType() == Type.NULL || (schema.getType() == Type.UNION && unionIsNullable(schema));
    }

    static boolean unionIsNullable(Schema unionSchema) {
        for (Schema schema : unionSchema.getTypes()) {
            if (schema.getType() == Type.NULL)
                return true;
        }
        return false;
    }

    static boolean isComplexType(Type type) {
        Preconditions.checkState(type != Type.UNION);
        return type == Type.ARRAY || type == Type.MAP || type == Type.RECORD;
    }

    static boolean isSimpleType(Schema schema) {
        if (schema.getType() == Type.UNION)
            schema = reduceUnionToNonNull(schema);
        return !isComplexType(schema.getType());
    }

    static boolean requiresChildDataset(Schema schema) {
        if (schema.getType() == Type.UNION)
            schema = reduceUnionToNonNull(schema);
        return schema.getType() == Type.ARRAY || schema.getType() == Type.MAP;
    }

    static boolean schemaHasNesting(Schema schema) {
        if (schema.getType() == Type.UNION)
            schema = reduceUnionToNonNull(schema);
        return isComplexType(schema.getType());
    }
}