Franck Tago created SPARK-44768:
-----------------------------------

             Summary: Improve WSCG handling of row buffer by accounting for 
executor memory
                 Key: SPARK-44768
                 URL: https://issues.apache.org/jira/browse/SPARK-44768
             Project: Spark
          Issue Type: Bug
          Components: Optimizer
    Affects Versions: 3.4.1, 3.4.0, 3.3.2
            Reporter: Franck Tago


consider a scenario where you flatten  a nested array 

// e.g you can use the following steps to create the dataframe 

/create a partClass
case class partClass (PARTNAME: String , PartNumber: String , PartPrice : 
Double )

//create a nested array array class
case  class array_array_class (
 col_int: Int,
 arr_arr_string : Seq[Seq[String]],
 arr_arr_bigint : Seq[Seq[Long]],
 col_string     : String,
 parts_s        : Seq[Seq[partClass]]
 
)

//create a dataframe
var df_array_array = sc.parallelize(
 Seq(
 (1,Seq(Seq("a","b" ,"c" ,"d") ,Seq("aa","bb" ,"cc","dd")) , 
Seq(Seq(1000,20000), Seq(30000,-10000)),"ItemPart1",
  Seq(Seq(partClass("PNAME1","P1",20.75),partClass("PNAME1_1","P1_1",30.75)))
 ) ,
 
 (2,Seq(Seq("ab","bc" ,"cd" ,"de") ,Seq("aab","bbc" 
,"ccd","dde"),Seq("aaaaaabbbbb")) , Seq(Seq(-1000,-20000,-1,-2), 
Seq(0,30000,-10000)),"ItemPart2",
  
Seq(Seq(partClass("PNAME2","P2",170.75),partClass("PNAME2_1","P2_1",33.75),partClass("PNAME2_2","P2_2",73.75)))
 )
  
 )

).toDF("c1" ,"c2" ,"c3" ,"c4" ,"c5")

//explode a nested array 

var  result   =  df_array_array.select( col("c1"), 
explode(col("c2"))).select('c1 , explode('col))

result.explain

 

The physical for this operator is seen below.

-------------------------------------
Physical plan 

== Physical Plan ==
*(1) Generate explode(col#27), [c1#17], false, [col#30]
+- *(1) Filter ((size(col#27, true) > 0) AND isnotnull(col#27))
   +- *(1) Generate explode(c2#18), [c1#17], false, [col#27]
      +- *(1) Project [_1#6 AS c1#17, _2#7 AS c2#18]
         +- *(1) Filter ((size(_2#7, true) > 0) AND isnotnull(_2#7))
            +- *(1) SerializeFromObject [knownnotnull(assertnotnull(input[0, 
scala.Tuple5, true]))._1 AS _1#6, mapobjects(lambdavariable(MapObject, 
ObjectType(class java.lang.Object), true, -1), 
mapobjects(lambdavariable(MapObject, ObjectType(class java.lang.Object), true, 
-2), staticinvoke(class org.apache.spark.unsafe.types.UTF8String, StringType, 
fromString, validateexternaltype(lambdavariable(MapObject, ObjectType(class 
java.lang.Object), true, -2), StringType, ObjectType(class java.lang.String)), 
true, false, true), validateexternaltype(lambdavariable(MapObject, 
ObjectType(class java.lang.Object), true, -1), ArrayType(StringType,true), 
ObjectType(interface scala.collection.Seq)), None), 
knownnotnull(assertnotnull(input[0, scala.Tuple5, true]))._2, None) AS _2#7, 
mapobjects(lambdavariable(MapObject, ObjectType(class java.lang.Object), true, 
-3), mapobjects(lambdavariable(MapObject, ObjectType(class java.lang.Object), 
true, -4), assertnotnull(validateexternaltype(lambdavariable(MapObject, 
ObjectType(class java.lang.Object), true, -4), IntegerType, IntegerType)), 
validateexternaltype(lambdavariable(MapObject, ObjectType(class 
java.lang.Object), true, -3), ArrayType(IntegerType,false), 
ObjectType(interface scala.collection.Seq)), None), 
knownnotnull(assertnotnull(input[0, scala.Tuple5, true]))._3, None) AS _3#8, 
staticinvoke(class org.apache.spark.unsafe.types.UTF8String, StringType, 
fromString, knownnotnull(assertnotnull(input[0, scala.Tuple5, true]))._4, true, 
false, true) AS _4#9, mapobjects(lambdavariable(MapObject, ObjectType(class 
java.lang.Object), true, -5), mapobjects(lambdavariable(MapObject, 
ObjectType(class java.lang.Object), true, -6), if 
(isnull(validateexternaltype(lambdavariable(MapObject, ObjectType(class 
java.lang.Object), true, -6), StructField(PARTNAME,StringType,true), 
StructField(PartNumber,StringType,true), 
StructField(PartPrice,DoubleType,false), ObjectType(class 
$line14.$read$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw$partClass)))) null else 
named_struct(PARTNAME, staticinvoke(class 
org.apache.spark.unsafe.types.UTF8String, StringType, fromString, 
knownnotnull(validateexternaltype(lambdavariable(MapObject, ObjectType(class 
java.lang.Object), true, -6), StructField(PARTNAME,StringType,true), 
StructField(PartNumber,StringType,true), 
StructField(PartPrice,DoubleType,false), ObjectType(class 
$line14.$read$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw$partClass))).PARTNAME, true, 
false, true), PartNumber, staticinvoke(class 
org.apache.spark.unsafe.types.UTF8String, StringType, fromString, 
knownnotnull(validateexternaltype(lambdavariable(MapObject, ObjectType(class 
java.lang.Object), true, -6), StructField(PARTNAME,StringType,true), 
StructField(PartNumber,StringType,true), 
StructField(PartPrice,DoubleType,false), ObjectType(class 
$line14.$read$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw$partClass))).PartNumber, true, 
false, true), PartPrice, 
knownnotnull(validateexternaltype(lambdavariable(MapObject, ObjectType(class 
java.lang.Object), true, -6), StructField(PARTNAME,StringType,true), 
StructField(PartNumber,StringType,true), 
StructField(PartPrice,DoubleType,false), ObjectType(class 
$line14.$read$$iw$$iw$$iw$$iw$$iw$$iw$$iw$$iw$partClass))).PartPrice), 
validateexternaltype(lambdavariable(MapObject, ObjectType(class 
java.lang.Object), true, -5), 
ArrayType(StructType(StructField(PARTNAME,StringType,true),StructField(PartNumber,StringType,true),StructField(PartPrice,DoubleType,false)),true),
 ObjectType(interface scala.collection.Seq)), None), 
knownnotnull(assertnotnull(input[0, scala.Tuple5, true]))._5, None) AS _5#10]
               +- Scan[obj#5]

 

 

Because the explode function can create multiple rows from a single row  , we 
should account for the memory available when adding rows to the buffer .  

 

This is even more important when we are exploding nested arrays . 



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