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Split up JsonRDD2 into multiple objects
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Nathan Howell
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May 4, 2015
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sql/core/src/main/scala/org/apache/spark/sql/json/InferSchema.scala
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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. | ||
*/ | ||
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package org.apache.spark.sql.json | ||
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import com.fasterxml.jackson.core._ | ||
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import org.apache.spark.rdd.RDD | ||
import org.apache.spark.sql.catalyst.analysis.HiveTypeCoercion | ||
import org.apache.spark.sql.json.JacksonUtils.nextUntil | ||
import org.apache.spark.sql.types._ | ||
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private[sql] object InferSchema { | ||
/** | ||
* Infer the type of a collection of json records in three stages: | ||
* 1. Infer the type of each record | ||
* 2. Merge types by choosing the lowest type necessary to cover equal keys | ||
* 3. Replace any remaining null fields with string, the top type | ||
*/ | ||
def apply( | ||
json: RDD[String], | ||
samplingRatio: Double = 1.0, | ||
columnNameOfCorruptRecords: String): StructType = { | ||
require(samplingRatio > 0, s"samplingRatio ($samplingRatio) should be greater than 0") | ||
val schemaData = if (samplingRatio > 0.99) { | ||
json | ||
} else { | ||
json.sample(withReplacement = false, samplingRatio, 1) | ||
} | ||
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// perform schema inference on each row and merge afterwards | ||
schemaData.mapPartitions { iter => | ||
val factory = new JsonFactory() | ||
iter.map { row => | ||
try { | ||
val parser = factory.createParser(row) | ||
parser.nextToken() | ||
inferField(parser) | ||
} catch { | ||
case _: JsonParseException => | ||
StructType(Seq(StructField(columnNameOfCorruptRecords, StringType))) | ||
} | ||
} | ||
}.treeAggregate[DataType](StructType(Seq()))(compatibleRootType, compatibleRootType) match { | ||
case st: StructType => nullTypeToStringType(st) | ||
} | ||
} | ||
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/** | ||
* Infer the type of a json document from the parser's token stream | ||
*/ | ||
private def inferField(parser: JsonParser): DataType = { | ||
import com.fasterxml.jackson.core.JsonToken._ | ||
parser.getCurrentToken match { | ||
case null | VALUE_NULL => NullType | ||
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case FIELD_NAME => | ||
parser.nextToken() | ||
inferField(parser) | ||
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case VALUE_STRING if parser.getTextLength < 1 => | ||
// Zero length strings and nulls have special handling to deal | ||
// with JSON generators that do not distinguish between the two. | ||
// To accurately infer types for empty strings that are really | ||
// meant to represent nulls we assume that the two are isomorphic | ||
// but will defer treating null fields as strings until all the | ||
// record fields' types have been combined. | ||
NullType | ||
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case VALUE_STRING => StringType | ||
case START_OBJECT => | ||
val builder = Seq.newBuilder[StructField] | ||
while (nextUntil(parser, END_OBJECT)) { | ||
builder += StructField(parser.getCurrentName, inferField(parser), nullable = true) | ||
} | ||
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StructType(builder.result().sortBy(_.name)) | ||
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case START_ARRAY => | ||
// If this JSON array is empty, we use NullType as a placeholder. | ||
// If this array is not empty in other JSON objects, we can resolve | ||
// the type as we pass through all JSON objects. | ||
var elementType: DataType = NullType | ||
while (nextUntil(parser, END_ARRAY)) { | ||
elementType = compatibleType(elementType, inferField(parser)) | ||
} | ||
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ArrayType(elementType) | ||
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case VALUE_NUMBER_INT | VALUE_NUMBER_FLOAT => | ||
import JsonParser.NumberType._ | ||
parser.getNumberType match { | ||
// For Integer values, use LongType by default. | ||
case INT | LONG => LongType | ||
// Since we do not have a data type backed by BigInteger, | ||
// when we see a Java BigInteger, we use DecimalType. | ||
case BIG_INTEGER | BIG_DECIMAL => DecimalType.Unlimited | ||
case FLOAT | DOUBLE => DoubleType | ||
} | ||
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case VALUE_TRUE | VALUE_FALSE => BooleanType | ||
} | ||
} | ||
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private def nullTypeToStringType(struct: StructType): StructType = { | ||
val fields = struct.fields.map { | ||
case StructField(fieldName, dataType, nullable, _) => | ||
val newType = dataType match { | ||
case NullType => StringType | ||
case ArrayType(NullType, containsNull) => ArrayType(StringType, containsNull) | ||
case ArrayType(struct: StructType, containsNull) => | ||
ArrayType(nullTypeToStringType(struct), containsNull) | ||
case struct: StructType =>nullTypeToStringType(struct) | ||
case other: DataType => other | ||
} | ||
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StructField(fieldName, newType, nullable) | ||
} | ||
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StructType(fields) | ||
} | ||
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/** | ||
* Remove top-level ArrayType wrappers and merge the remaining schemas | ||
*/ | ||
private def compatibleRootType: (DataType, DataType) => DataType = { | ||
case (ArrayType(ty1, _), ty2) => compatibleRootType(ty1, ty2) | ||
case (ty1, ArrayType(ty2, _)) => compatibleRootType(ty1, ty2) | ||
case (ty1, ty2) => compatibleType(ty1, ty2) | ||
} | ||
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/** | ||
* Returns the most general data type for two given data types. | ||
*/ | ||
private[json] def compatibleType(t1: DataType, t2: DataType): DataType = { | ||
HiveTypeCoercion.findTightestCommonType(t1, t2).getOrElse { | ||
// t1 or t2 is a StructType, ArrayType, or an unexpected type. | ||
(t1, t2) match { | ||
case (other: DataType, NullType) => other | ||
case (NullType, other: DataType) => other | ||
case (StructType(fields1), StructType(fields2)) => | ||
val newFields = (fields1 ++ fields2).groupBy(field => field.name).map { | ||
case (name, fieldTypes) => | ||
val dataType = fieldTypes.view.map(_.dataType).reduce(compatibleType) | ||
StructField(name, dataType, nullable = true) | ||
} | ||
StructType(newFields.toSeq.sortBy(_.name)) | ||
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case (ArrayType(elementType1, containsNull1), ArrayType(elementType2, containsNull2)) => | ||
ArrayType(compatibleType(elementType1, elementType2), containsNull1 || containsNull2) | ||
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// strings and every string is a Json object. | ||
case (_, _) => StringType | ||
} | ||
} | ||
} | ||
} |
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77
sql/core/src/main/scala/org/apache/spark/sql/json/JacksonGenerator.scala
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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. | ||
*/ | ||
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package org.apache.spark.sql.json | ||
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import scala.collection.Map | ||
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import com.fasterxml.jackson.core._ | ||
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import org.apache.spark.sql.catalyst.expressions._ | ||
import org.apache.spark.sql.types._ | ||
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private[sql] object JacksonGenerator { | ||
/** Transforms a single Row to JSON using Jackson | ||
* | ||
* @param rowSchema the schema object used for conversion | ||
* @param gen a JsonGenerator object | ||
* @param row The row to convert | ||
*/ | ||
def apply(rowSchema: StructType, gen: JsonGenerator)(row: Row): Unit = { | ||
def valWriter: (DataType, Any) => Unit = { | ||
case (_, null) | (NullType, _) => gen.writeNull() | ||
case (StringType, v: String) => gen.writeString(v) | ||
case (TimestampType, v: java.sql.Timestamp) => gen.writeString(v.toString) | ||
case (IntegerType, v: Int) => gen.writeNumber(v) | ||
case (ShortType, v: Short) => gen.writeNumber(v) | ||
case (FloatType, v: Float) => gen.writeNumber(v) | ||
case (DoubleType, v: Double) => gen.writeNumber(v) | ||
case (LongType, v: Long) => gen.writeNumber(v) | ||
case (DecimalType(), v: java.math.BigDecimal) => gen.writeNumber(v) | ||
case (ByteType, v: Byte) => gen.writeNumber(v.toInt) | ||
case (BinaryType, v: Array[Byte]) => gen.writeBinary(v) | ||
case (BooleanType, v: Boolean) => gen.writeBoolean(v) | ||
case (DateType, v) => gen.writeString(v.toString) | ||
case (udt: UserDefinedType[_], v) => valWriter(udt.sqlType, udt.serialize(v)) | ||
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case (ArrayType(ty, _), v: Seq[_] ) => | ||
gen.writeStartArray() | ||
v.foreach(valWriter(ty,_)) | ||
gen.writeEndArray() | ||
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case (MapType(kv,vv, _), v: Map[_,_]) => | ||
gen.writeStartObject() | ||
v.foreach { p => | ||
gen.writeFieldName(p._1.toString) | ||
valWriter(vv,p._2) | ||
} | ||
gen.writeEndObject() | ||
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case (StructType(ty), v: Row) => | ||
gen.writeStartObject() | ||
ty.zip(v.toSeq).foreach { | ||
case (_, null) => | ||
case (field, v) => | ||
gen.writeFieldName(field.name) | ||
valWriter(field.dataType, v) | ||
} | ||
gen.writeEndObject() | ||
} | ||
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valWriter(rowSchema, row) | ||
} | ||
} |
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