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[SPARK-4413][SQL] Parquet support through datasource API
Goals: - Support for accessing parquet using SQL but not requiring Hive (thus allowing support of parquet tables with decimal columns) - Support for folder based partitioning with automatic discovery of available partitions - Caching of file metadata See scaladoc of `ParquetRelation2` for more details. Author: Michael Armbrust <michael@databricks.com> Closes apache#3269 from marmbrus/newParquet and squashes the following commits: 1dd75f1 [Michael Armbrust] Pass all paths for FileInputFormat at once. 645768b [Michael Armbrust] Review comments. abd8e2f [Michael Armbrust] Alternative implementation of parquet based on the datasources API. 938019e [Michael Armbrust] Add an experimental interface to data sources that exposes catalyst expressions. e9d2641 [Michael Armbrust] logging / formatting improvements.
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sql/core/src/main/scala/org/apache/spark/sql/parquet/newParquet.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. | ||
*/ | ||
package org.apache.spark.sql.parquet | ||
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import java.util.{List => JList} | ||
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import org.apache.hadoop.fs.{FileStatus, FileSystem, Path} | ||
import org.apache.hadoop.conf.{Configurable, Configuration} | ||
import org.apache.hadoop.io.Writable | ||
import org.apache.hadoop.mapreduce.{JobContext, InputSplit, Job} | ||
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import parquet.hadoop.ParquetInputFormat | ||
import parquet.hadoop.util.ContextUtil | ||
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import org.apache.spark.annotation.DeveloperApi | ||
import org.apache.spark.{Partition => SparkPartition, Logging} | ||
import org.apache.spark.rdd.{NewHadoopPartition, RDD} | ||
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import org.apache.spark.sql.{SQLConf, Row, SQLContext} | ||
import org.apache.spark.sql.catalyst.expressions.{SpecificMutableRow, And, Expression, Attribute} | ||
import org.apache.spark.sql.catalyst.types.{IntegerType, StructField, StructType} | ||
import org.apache.spark.sql.sources._ | ||
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import scala.collection.JavaConversions._ | ||
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/** | ||
* Allows creation of parquet based tables using the syntax | ||
* `CREATE TABLE ... USING org.apache.spark.sql.parquet`. Currently the only option required | ||
* is `path`, which should be the location of a collection of, optionally partitioned, | ||
* parquet files. | ||
*/ | ||
class DefaultSource extends RelationProvider { | ||
/** Returns a new base relation with the given parameters. */ | ||
override def createRelation( | ||
sqlContext: SQLContext, | ||
parameters: Map[String, String]): BaseRelation = { | ||
val path = | ||
parameters.getOrElse("path", sys.error("'path' must be specifed for parquet tables.")) | ||
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ParquetRelation2(path)(sqlContext) | ||
} | ||
} | ||
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private[parquet] case class Partition(partitionValues: Map[String, Any], files: Seq[FileStatus]) | ||
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/** | ||
* An alternative to [[ParquetRelation]] that plugs in using the data sources API. This class is | ||
* currently not intended as a full replacement of the parquet support in Spark SQL though it is | ||
* likely that it will eventually subsume the existing physical plan implementation. | ||
* | ||
* Compared with the current implementation, this class has the following notable differences: | ||
* | ||
* Partitioning: Partitions are auto discovered and must be in the form of directories `key=value/` | ||
* located at `path`. Currently only a single partitioning column is supported and it must | ||
* be an integer. This class supports both fully self-describing data, which contains the partition | ||
* key, and data where the partition key is only present in the folder structure. The presence | ||
* of the partitioning key in the data is also auto-detected. The `null` partition is not yet | ||
* supported. | ||
* | ||
* Metadata: The metadata is automatically discovered by reading the first parquet file present. | ||
* There is currently no support for working with files that have different schema. Additionally, | ||
* when parquet metadata caching is turned on, the FileStatus objects for all data will be cached | ||
* to improve the speed of interactive querying. When data is added to a table it must be dropped | ||
* and recreated to pick up any changes. | ||
* | ||
* Statistics: Statistics for the size of the table are automatically populated during metadata | ||
* discovery. | ||
*/ | ||
@DeveloperApi | ||
case class ParquetRelation2(path: String)(@transient val sqlContext: SQLContext) | ||
extends CatalystScan with Logging { | ||
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def sparkContext = sqlContext.sparkContext | ||
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// Minor Hack: scala doesnt seem to respect @transient for vals declared via extraction | ||
@transient | ||
private var partitionKeys: Seq[String] = _ | ||
@transient | ||
private var partitions: Seq[Partition] = _ | ||
discoverPartitions() | ||
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// TODO: Only finds the first partition, assumes the key is of type Integer... | ||
private def discoverPartitions() = { | ||
val fs = FileSystem.get(new java.net.URI(path), sparkContext.hadoopConfiguration) | ||
val partValue = "([^=]+)=([^=]+)".r | ||
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val childrenOfPath = fs.listStatus(new Path(path)).filterNot(_.getPath.getName.startsWith("_")) | ||
val childDirs = childrenOfPath.filter(s => s.isDir) | ||
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if (childDirs.size > 0) { | ||
val partitionPairs = childDirs.map(_.getPath.getName).map { | ||
case partValue(key, value) => (key, value) | ||
} | ||
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val foundKeys = partitionPairs.map(_._1).distinct | ||
if (foundKeys.size > 1) { | ||
sys.error(s"Too many distinct partition keys: $foundKeys") | ||
} | ||
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// Do a parallel lookup of partition metadata. | ||
val partitionFiles = | ||
childDirs.par.map { d => | ||
fs.listStatus(d.getPath) | ||
// TODO: Is there a standard hadoop function for this? | ||
.filterNot(_.getPath.getName.startsWith("_")) | ||
.filterNot(_.getPath.getName.startsWith(".")) | ||
}.seq | ||
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partitionKeys = foundKeys.toSeq | ||
partitions = partitionFiles.zip(partitionPairs).map { case (files, (key, value)) => | ||
Partition(Map(key -> value.toInt), files) | ||
}.toSeq | ||
} else { | ||
partitionKeys = Nil | ||
partitions = Partition(Map.empty, childrenOfPath) :: Nil | ||
} | ||
} | ||
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override val sizeInBytes = partitions.flatMap(_.files).map(_.getLen).sum | ||
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val dataSchema = StructType.fromAttributes( // TODO: Parquet code should not deal with attributes. | ||
ParquetTypesConverter.readSchemaFromFile( | ||
partitions.head.files.head.getPath, | ||
Some(sparkContext.hadoopConfiguration), | ||
sqlContext.isParquetBinaryAsString)) | ||
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val dataIncludesKey = | ||
partitionKeys.headOption.map(dataSchema.fieldNames.contains(_)).getOrElse(true) | ||
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override val schema = | ||
if (dataIncludesKey) { | ||
dataSchema | ||
} else { | ||
StructType(dataSchema.fields :+ StructField(partitionKeys.head, IntegerType)) | ||
} | ||
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override def buildScan(output: Seq[Attribute], predicates: Seq[Expression]): RDD[Row] = { | ||
// This is mostly a hack so that we can use the existing parquet filter code. | ||
val requiredColumns = output.map(_.name) | ||
// TODO: Parquet filters should be based on data sources API, not catalyst expressions. | ||
val filters = DataSourceStrategy.selectFilters(predicates) | ||
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val job = new Job(sparkContext.hadoopConfiguration) | ||
ParquetInputFormat.setReadSupportClass(job, classOf[RowReadSupport]) | ||
val jobConf: Configuration = ContextUtil.getConfiguration(job) | ||
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val requestedSchema = StructType(requiredColumns.map(schema(_))) | ||
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// TODO: Make folder based partitioning a first class citizen of the Data Sources API. | ||
val partitionFilters = filters.collect { | ||
case e @ EqualTo(attr, value) if partitionKeys.contains(attr) => | ||
logInfo(s"Parquet scan partition filter: $attr=$value") | ||
(p: Partition) => p.partitionValues(attr) == value | ||
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case e @ In(attr, values) if partitionKeys.contains(attr) => | ||
logInfo(s"Parquet scan partition filter: $attr IN ${values.mkString("{", ",", "}")}") | ||
val set = values.toSet | ||
(p: Partition) => set.contains(p.partitionValues(attr)) | ||
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case e @ GreaterThan(attr, value) if partitionKeys.contains(attr) => | ||
logInfo(s"Parquet scan partition filter: $attr > $value") | ||
(p: Partition) => p.partitionValues(attr).asInstanceOf[Int] > value.asInstanceOf[Int] | ||
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case e @ GreaterThanOrEqual(attr, value) if partitionKeys.contains(attr) => | ||
logInfo(s"Parquet scan partition filter: $attr >= $value") | ||
(p: Partition) => p.partitionValues(attr).asInstanceOf[Int] >= value.asInstanceOf[Int] | ||
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case e @ LessThan(attr, value) if partitionKeys.contains(attr) => | ||
logInfo(s"Parquet scan partition filter: $attr < $value") | ||
(p: Partition) => p.partitionValues(attr).asInstanceOf[Int] < value.asInstanceOf[Int] | ||
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case e @ LessThanOrEqual(attr, value) if partitionKeys.contains(attr) => | ||
logInfo(s"Parquet scan partition filter: $attr <= $value") | ||
(p: Partition) => p.partitionValues(attr).asInstanceOf[Int] <= value.asInstanceOf[Int] | ||
} | ||
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val selectedPartitions = partitions.filter(p => partitionFilters.forall(_(p))) | ||
val fs = FileSystem.get(new java.net.URI(path), sparkContext.hadoopConfiguration) | ||
val selectedFiles = selectedPartitions.flatMap(_.files).map(f => fs.makeQualified(f.getPath)) | ||
org.apache.hadoop.mapreduce.lib.input.FileInputFormat.setInputPaths(job, selectedFiles:_*) | ||
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// Push down filters when possible | ||
predicates | ||
.reduceOption(And) | ||
.flatMap(ParquetFilters.createFilter) | ||
.filter(_ => sqlContext.parquetFilterPushDown) | ||
.foreach(ParquetInputFormat.setFilterPredicate(jobConf, _)) | ||
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def percentRead = selectedPartitions.size.toDouble / partitions.size.toDouble * 100 | ||
logInfo(s"Reading $percentRead% of $path partitions") | ||
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// Store both requested and original schema in `Configuration` | ||
jobConf.set( | ||
RowReadSupport.SPARK_ROW_REQUESTED_SCHEMA, | ||
ParquetTypesConverter.convertToString(requestedSchema.toAttributes)) | ||
jobConf.set( | ||
RowWriteSupport.SPARK_ROW_SCHEMA, | ||
ParquetTypesConverter.convertToString(schema.toAttributes)) | ||
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// Tell FilteringParquetRowInputFormat whether it's okay to cache Parquet and FS metadata | ||
val useCache = sqlContext.getConf(SQLConf.PARQUET_CACHE_METADATA, "true").toBoolean | ||
jobConf.set(SQLConf.PARQUET_CACHE_METADATA, useCache.toString) | ||
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val baseRDD = | ||
new org.apache.spark.rdd.NewHadoopRDD( | ||
sparkContext, | ||
classOf[FilteringParquetRowInputFormat], | ||
classOf[Void], | ||
classOf[Row], | ||
jobConf) { | ||
val cacheMetadata = useCache | ||
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@transient | ||
val cachedStatus = selectedPartitions.flatMap(_.files) | ||
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// Overridden so we can inject our own cached files statuses. | ||
override def getPartitions: Array[SparkPartition] = { | ||
val inputFormat = | ||
if (cacheMetadata) { | ||
new FilteringParquetRowInputFormat { | ||
override def listStatus(jobContext: JobContext): JList[FileStatus] = cachedStatus | ||
} | ||
} else { | ||
new FilteringParquetRowInputFormat | ||
} | ||
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inputFormat match { | ||
case configurable: Configurable => | ||
configurable.setConf(getConf) | ||
case _ => | ||
} | ||
val jobContext = newJobContext(getConf, jobId) | ||
val rawSplits = inputFormat.getSplits(jobContext).toArray | ||
val result = new Array[SparkPartition](rawSplits.size) | ||
for (i <- 0 until rawSplits.size) { | ||
result(i) = | ||
new NewHadoopPartition(id, i, rawSplits(i).asInstanceOf[InputSplit with Writable]) | ||
} | ||
result | ||
} | ||
} | ||
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// The ordinal for the partition key in the result row, if requested. | ||
val partitionKeyLocation = | ||
partitionKeys | ||
.headOption | ||
.map(requiredColumns.indexOf(_)) | ||
.getOrElse(-1) | ||
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// When the data does not include the key and the key is requested then we must fill it in | ||
// based on information from the input split. | ||
if (!dataIncludesKey && partitionKeyLocation != -1) { | ||
baseRDD.mapPartitionsWithInputSplit { case (split, iter) => | ||
val partValue = "([^=]+)=([^=]+)".r | ||
val partValues = | ||
split.asInstanceOf[parquet.hadoop.ParquetInputSplit] | ||
.getPath | ||
.toString | ||
.split("/") | ||
.flatMap { | ||
case partValue(key, value) => Some(key -> value) | ||
case _ => None | ||
}.toMap | ||
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val currentValue = partValues.values.head.toInt | ||
iter.map { pair => | ||
val res = pair._2.asInstanceOf[SpecificMutableRow] | ||
res.setInt(partitionKeyLocation, currentValue) | ||
res | ||
} | ||
} | ||
} else { | ||
baseRDD.map(_._2) | ||
} | ||
} | ||
} |
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