hvanhovell commented on a change in pull request #26013: [SPARK-29347][SQL] Add
JSON serialization for external Rows
URL: https://github.com/apache/spark/pull/26013#discussion_r332182808
##########
File path: sql/catalyst/src/main/scala/org/apache/spark/sql/Row.scala
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@@ -501,4 +513,88 @@ trait Row extends Serializable {
private def getAnyValAs[T <: AnyVal](i: Int): T =
if (isNullAt(i)) throw new NullPointerException(s"Value at index $i is
null")
else getAs[T](i)
+
+ /** The compact JSON representation of this row. */
+ def json: String = compact(jsonValue)
Review comment:
So two things to consider here.
I want to use this in StreamingQueryProgress right? All the JSON
serialization there is based on the json4s AST and not strings (which is what
JacksonGenerator produces).
There is a difference between it being slow, and what you are suggesting.
The latter being crazy inefficient. Let's break that down:
- Row to InternalRow conversion. You will need to create a converter per row
because there is currently no way we can safely cache a converter. You can
either use `ScalaReflection` or `RowEncoder` here, the latter is particularly
bad because it uses code generation (which takes in the order of mills and
which is weakly cached on the driver).
- Setting up the JacksonGenerator, again this is uncached and we need to set
up the same thing for each tuple.
- Generating the string.
Do you see my point here? Or shall I write a benchmark?
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