Github user davies commented on a diff in the pull request:
https://github.com/apache/spark/pull/11055#discussion_r51952950
--- Diff: sql/core/src/main/scala/org/apache/spark/sql/SQLConf.scala ---
@@ -345,6 +345,14 @@ private[spark] object SQLConf {
defaultValue = Some(true),
doc = "Enables using the custom ParquetUnsafeRowRecordReader.")
+ // Note: this can not be enabled all the time because the reader will
not be returning UnsafeRows.
+ // Doing so is very expensive and we should remove this requirement
instead of fixing it here.
+ // Initial testing seems to indicate only sort requires this.
--- End diff --
Right, all the operators output UnsafeRow, some operators may depends on
some properties of UnsafeRow:
1). copy() returns UnsafeRow
2). getStruct() return UnsafeRow, getArray() return UnsafeArrayData,
getMap() returns UnsafeMap
3). hashCode() is murmur3 on bytes of UnsafeRow
4). compareTo() will compare the row as bytes
For example, the in-memory cache requires 2), except requires 4)
@rxin Do you have more comment on this?
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