bojana-db commented on code in PR #56864:
URL: https://github.com/apache/spark/pull/56864#discussion_r3748987498
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sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/variant/variantExpressions.scala:
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@@ -1490,6 +1490,92 @@ object VariantArrayAppendExpressionBuilder extends
VariantArrayAppendExpressionB
// scalastyle:on line.size.limit
object TryVariantArrayAppendExpressionBuilder
extends VariantArrayAppendExpressionBuilderBase(false)
+case class VariantStripNulls(child: Expression, includeArrays: Expression)
+ extends RuntimeReplaceable
+ with ExpectsInputTypes
+ with BinaryLike[Expression]
+ with QueryErrorsBase {
+
+ override def left: Expression = child
+ override def right: Expression = includeArrays
+
+ override def inputTypes: Seq[AbstractDataType] = Seq(VariantType,
BooleanType)
+
+ override def checkInputDataTypes(): TypeCheckResult = {
+ val result = super.checkInputDataTypes()
+ if (result.isFailure) {
+ result
+ } else if (!includeArrays.foldable) {
+ DataTypeMismatch(
+ errorSubClass = "NON_FOLDABLE_INPUT",
+ messageParameters = Map(
+ "inputName" -> toSQLId("include_arrays"),
+ "inputType" -> toSQLType(includeArrays.dataType),
+ "inputExpr" -> toSQLExpr(includeArrays)))
+ } else {
+ TypeCheckResult.TypeCheckSuccess
+ }
+ }
+
+ override lazy val replacement: Expression = StaticInvoke(
+ VariantExpressionEvalUtils.getClass,
+ VariantType,
+ "stripNulls",
+ Seq(child, includeArrays),
+ inputTypes,
+ returnNullable = false)
+
+ override def prettyName: String = "variant_strip_nulls"
+
+ override protected def withNewChildrenInternal(
+ newLeft: Expression, newRight: Expression): VariantStripNulls =
+ copy(child = newLeft, includeArrays = newRight)
+}
+
+// scalastyle:off line.size.limit
+@ExpressionDescription(
+ usage = "_FUNC_(v[, include_arrays]) - Recursively removes object fields and
array elements " +
+ "whose value is a variant null, unless `include_arrays` is false, in which
case null array " +
+ "elements are kept. Returns NULL if any argument is NULL.",
+ arguments = """
+ Arguments:
+ * v - A variant value to mutate.
+ * include_arrays - An optional boolean (default true). Must be a
constant.
Review Comment:
`variant_strip_nulls` mirrors BigQuery's
[JSON_STRIP_NULLS](https://docs.cloud.google.com/bigquery/docs/reference/standard-sql/json_functions#json_strip_nulls),
where `include_arrays` defaults to `TRUE`, so name and default both match
BigQuery. PostgreSQL's `strip_in_arrays=false` is a backward-compat default
(arrays were untouched before PG 18), not an analytics preference. BigQuery
frames the function as data compaction ( ["JSON_STRIP_NULLS compresses the data
by removing JSON nulls ... helpful for reducing data size during
exports"](https://cloud.google.com/blog/products/data-analytics/announcing-new-sql-functions-for-json-in-bigquery)
) which makes sense fot DW/analytics workload and for that use case you
generally want array nulls stripped too.
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