uros-b commented on code in PR #56550:
URL: https://github.com/apache/spark/pull/56550#discussion_r3431816808
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sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/jdbc/JdbcUtils.scala:
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@@ -354,6 +354,60 @@ object JdbcUtils extends Logging with SQLConfHelper {
internalRows.map(fromRow)
}
+ /**
+ * Estimates the size in bytes of a row given its schema. For
variable-length types
+ * (String, Binary), uses actual value size; for fixed-width types, uses
defaultSize.
+ * Null fields contribute 0 bytes.
+ */
+ private[jdbc] def estimateInternalRowSize(row: InternalRow, schema:
StructType): Long = {
+ var size = 0L
+ var i = 0
+ while (i < schema.length) {
+ if (!row.isNullAt(i)) {
+ schema.fields(i).dataType match {
+ case _: StringType =>
+ size += row.getUTF8String(i).numBytes()
+ case BinaryType =>
+ size += row.getBinary(i).length
+ case at: ArrayType =>
+ size += row.getArray(i).numElements().toLong *
at.elementType.defaultSize
Review Comment:
One note that's worth calling out here: ArrayType estimation is a bit coarse
for variable-length elements. Namely, for arrays of strings or binary,
defaultSize is 20 and 100 respectively, so not quite the actual element sizes.
JDBC does support arrays (Postgres, etc.), so metrics for ARRAY(TEXT) or
ARRAY(BYTEA) could potentially be significantly off.
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