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[SPARK-14259] [SQL] Merging small files together based on the cost of opening #12095

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[SPARK-14259] [SQL] Merging small files together based on the cost of opening #12095

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13 changes: 5 additions & 8 deletions sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/FileSourceStrategy.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -130,9 +130,9 @@ private[sql] object FileSourceStrategy extends Strategy with Logging {

case _ =>
val maxSplitBytes = files.sqlContext.conf.filesMaxPartitionBytes
val maxFileNumInPartition = files.sqlContext.conf.filesMaxNumInPartition
val openCostInBytes = files.sqlContext.conf.filesOpenCostInBytes
logInfo(s"Planning scan with bin packing, max size: $maxSplitBytes bytes, " +
s"max #files: $maxFileNumInPartition")
s"open cost is considered as scanning $openCostInBytes bytes.")

val splitFiles = selectedPartitions.flatMap { partition =>
partition.files.flatMap { file =>
Expand All @@ -150,7 +150,7 @@ private[sql] object FileSourceStrategy extends Strategy with Logging {

/** Add the given file to the current partition. */
def addFile(file: PartitionedFile): Unit = {
currentSize += file.length
currentSize += file.length + openCostInBytes
currentFiles.append(file)
}

Expand All @@ -170,13 +170,10 @@ private[sql] object FileSourceStrategy extends Strategy with Logging {
// Assign files to partitions using "First Fit Decreasing" (FFD)
// TODO: consider adding a slop factor here?
splitFiles.foreach { file =>
if (currentSize + file.length > maxSplitBytes ||
currentFiles.length >= maxFileNumInPartition) {
if (currentSize + file.length > maxSplitBytes) {
closePartition()
addFile(file)
} else {
addFile(file)
}
addFile(file)
}
closePartition()
partitions
Expand Down
13 changes: 8 additions & 5 deletions sql/core/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala
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Expand Up @@ -510,10 +510,13 @@ object SQLConf {
doc = "The maximum number of bytes to pack into a single partition when reading files.",
isPublic = true)

val FILES_MAX_NUM_IN_PARTITION = longConf("spark.sql.files.maxNumInPartition",
defaultValue = Some(32),
doc = "The maximum number of files to pack into a single partition when reading files.",
isPublic = true)
val FILES_OPEN_COST_IN_BYTES = longConf("spark.sql.files.openCostInBytes",
defaultValue = Some(4 * 1024 * 1024),
doc = "The estimated cost to open a file, measured by the number of bytes could be scanned in" +
" the same time. This is used when putting multiple files into a partition. It's better to" +
" over estimated, then the partitions with small files will be faster than partitions with" +
" bigger files (which is scheduled first).",
isPublic = false)

val EXCHANGE_REUSE_ENABLED = booleanConf("spark.sql.exchange.reuse",
defaultValue = Some(true),
Expand Down Expand Up @@ -572,7 +575,7 @@ class SQLConf extends Serializable with CatalystConf with Logging {

def filesMaxPartitionBytes: Long = getConf(FILES_MAX_PARTITION_BYTES)

def filesMaxNumInPartition: Long = getConf(FILES_MAX_NUM_IN_PARTITION)
def filesOpenCostInBytes: Long = getConf(FILES_OPEN_COST_IN_BYTES)

def useCompression: Boolean = getConf(COMPRESS_CACHED)

Expand Down
14 changes: 8 additions & 6 deletions ...e/src/test/scala/org/apache/spark/sql/execution/datasources/FileSourceStrategySuite.scala
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Expand Up @@ -76,7 +76,8 @@ class FileSourceStrategySuite extends QueryTest with SharedSQLContext with Predi
"file2" -> 5,
"file3" -> 5))

withSQLConf(SQLConf.FILES_MAX_PARTITION_BYTES.key -> "10") {
withSQLConf(SQLConf.FILES_MAX_PARTITION_BYTES.key -> "11",
SQLConf.FILES_OPEN_COST_IN_BYTES.key -> "1") {
checkScan(table.select('c1)) { partitions =>
// 5 byte files should be laid out [(5, 5), (5)]
assert(partitions.size == 2, "when checking partitions")
Expand All @@ -98,11 +99,12 @@ class FileSourceStrategySuite extends QueryTest with SharedSQLContext with Predi
createTable(
files = Seq(
"file1" -> 15,
"file2" -> 4))
"file2" -> 3))

withSQLConf(SQLConf.FILES_MAX_PARTITION_BYTES.key -> "10") {
withSQLConf(SQLConf.FILES_MAX_PARTITION_BYTES.key -> "10",
SQLConf.FILES_OPEN_COST_IN_BYTES.key -> "1") {
checkScan(table.select('c1)) { partitions =>
// Files should be laid out [(0-5), (5-10, 4)]
// Files should be laid out [(0-10), (10-15, 4)]
assert(partitions.size == 2, "when checking partitions")
assert(partitions(0).files.size == 1, "when checking partition 1")
assert(partitions(1).files.size == 2, "when checking partition 2")
Expand Down Expand Up @@ -132,8 +134,8 @@ class FileSourceStrategySuite extends QueryTest with SharedSQLContext with Predi
"file5" -> 1,
"file6" -> 1))

withSQLConf(SQLConf.FILES_MAX_PARTITION_BYTES.key -> "3",
SQLConf.FILES_MAX_NUM_IN_PARTITION.key -> "2") {
withSQLConf(SQLConf.FILES_MAX_PARTITION_BYTES.key -> "4",
SQLConf.FILES_OPEN_COST_IN_BYTES.key -> "1") {
checkScan(table.select('c1)) { partitions =>
// Files should be laid out [(file1), (file2, file3), (file4, file5), (file6)]
assert(partitions.size == 4, "when checking partitions")
Expand Down