diff --git a/spark-plugin/plugin/src/main/scala/org/apache/spark/dataflint/DataFlintRDDUtils.scala b/spark-plugin/plugin/src/main/scala/org/apache/spark/dataflint/DataFlintRDDUtils.scala
index 2106a9e..3a2d5a4 100644
--- a/spark-plugin/plugin/src/main/scala/org/apache/spark/dataflint/DataFlintRDDUtils.scala
+++ b/spark-plugin/plugin/src/main/scala/org/apache/spark/dataflint/DataFlintRDDUtils.scala
@@ -1,5 +1,6 @@
 package org.apache.spark.dataflint
 
+import org.apache.spark.{Partition, TaskContext}
 import org.apache.spark.rdd.RDD
 import org.apache.spark.sql.catalyst.InternalRow
 import org.apache.spark.sql.execution.metric.SQLMetric
@@ -7,36 +8,44 @@ import org.apache.spark.sql.vectorized.ColumnarBatch
 
 object DataFlintRDDUtils {
   def withDurationMetric(rdd: RDD[InternalRow], durationMetric: SQLMetric): RDD[InternalRow] =
-    rdd.mapPartitions { iter =>
-      val startTime = System.nanoTime()
-      var done = false
-      new Iterator[InternalRow] {
-        override def hasNext: Boolean = {
-          val r = iter.hasNext
-          if (!r && !done) {
-            durationMetric += ((System.nanoTime() - startTime)/(1000 * 1000))
-            done = true
+    new RDD[InternalRow](rdd) {
+      override def compute(split: Partition, context: TaskContext): Iterator[InternalRow] = {
+        val startTime = System.nanoTime()
+        val iter = firstParent[InternalRow].iterator(split, context)
+        var done = false
+        new Iterator[InternalRow] {
+          override def hasNext: Boolean = {
+            val r = iter.hasNext
+            if (!r && !done) {
+              durationMetric += (System.nanoTime() - startTime) / (1000 * 1000)
+              done = true
+            }
+            r
           }
-          r
+          override def next(): InternalRow = iter.next()
         }
-        override def next(): InternalRow = iter.next()
       }
+      override protected def getPartitions: Array[Partition] = firstParent.partitions
     }
 
   def withDurationMetricColumnar(rdd: RDD[ColumnarBatch], durationMetric: SQLMetric): RDD[ColumnarBatch] =
-    rdd.mapPartitions { iter =>
-      val startTime = System.nanoTime()
-      var done = false
-      new Iterator[ColumnarBatch] {
-        override def hasNext: Boolean = {
-          val r = iter.hasNext
-          if (!r && !done) {
-            durationMetric += ((System.nanoTime() - startTime) / (1000 * 1000))
-            done = true
+    new RDD[ColumnarBatch](rdd) {
+      override def compute(split: Partition, context: TaskContext): Iterator[ColumnarBatch] = {
+        val startTime = System.nanoTime()
+        val iter = firstParent[ColumnarBatch].iterator(split, context)
+        var done = false
+        new Iterator[ColumnarBatch] {
+          override def hasNext: Boolean = {
+            val r = iter.hasNext
+            if (!r && !done) {
+              durationMetric += (System.nanoTime() - startTime) / (1000 * 1000)
+              done = true
+            }
+            r
           }
-          r
+          override def next(): ColumnarBatch = iter.next()
         }
-        override def next(): ColumnarBatch = iter.next()
       }
+      override protected def getPartitions: Array[Partition] = firstParent.partitions
     }
 }
\ No newline at end of file
diff --git a/spark-plugin/plugin/src/main/scala/org/apache/spark/dataflint/SlowSumAggregator.scala b/spark-plugin/plugin/src/main/scala/org/apache/spark/dataflint/SlowSumAggregator.scala
index 9defd45..773a3d6 100644
--- a/spark-plugin/plugin/src/main/scala/org/apache/spark/dataflint/SlowSumAggregator.scala
+++ b/spark-plugin/plugin/src/main/scala/org/apache/spark/dataflint/SlowSumAggregator.scala
@@ -16,7 +16,7 @@ class SlowSumAggregator extends Aggregator[Double, Double, Double] {
   private lazy val sleepMs: Long = {
     try {
       val sc = org.apache.spark.SparkContext.getActive
-      sc.map(_.conf.getLong("spark.dataflint.test.slowSumSleepMs", 1L)).getOrElse(1L)
+      sc.map(_.conf.getLong("spark.dataflint.test.slowSumSleepMs", 1L)).getOrElse(0L)
     } catch {
       case _: Throwable => 1L
     }
diff --git a/spark-plugin/plugin/src/main/scala/org/apache/spark/dataflint/TimedExec.scala b/spark-plugin/plugin/src/main/scala/org/apache/spark/dataflint/TimedExec.scala
index 0f04f32..7ecf5b9 100644
--- a/spark-plugin/plugin/src/main/scala/org/apache/spark/dataflint/TimedExec.scala
+++ b/spark-plugin/plugin/src/main/scala/org/apache/spark/dataflint/TimedExec.scala
@@ -80,17 +80,36 @@ class TimedExec(val child: SparkPlan) extends SparkPlan with CodegenSupport with
 
   // Write path: DataWritingCommandExec does work eagerly in sideEffectResult (a lazy val),
   // triggered by executeCollect(). doExecute()/withDurationMetric only wraps the trivial
-  // result RDD and misses the actual I/O. This override captures the full write duration.
-  // For non-write nodes this is harmless — executeCollect() on TimedExec is only called
-  // when TimedExec is the plan root (writes), not when it's inside WSCE (codegen path).
+  // result RDD and misses the actual I/O.
+  //
+  // To get per-partition timing (consistent with codegen/RDD paths), we reconstruct
+  // DataWritingCommandExec with the data-producing plan wrapped in an RDDTimingWrapper.
+  // The write command consumes this timed RDD via sparkContext.runJob, so the wall-clock-
+  // per-partition timing captures both data production AND write I/O (writes happen between
+  // next() calls on the timed iterator).
+  //
+  // Spark 3.4+ inserts WriteFilesExec between DataWritingCommandExec and the data plan.
+  // cmd.run() type-checks for WriteFilesExec, so we wrap the data plan INSIDE WriteFilesExec
+  // (one level deeper), preserving the type check. On older Spark we wrap the child directly.
   override def executeCollect(): Array[InternalRow] = {
-    val start = System.nanoTime()
-    val result = child.executeCollect()
-    val durationMs = (System.nanoTime() - start) / (1000 * 1000)
-    val durationMetric = longMetric("duration")
-    durationMetric += durationMs
-    MetricsUtils.postDriverMetrics(sparkContext, durationMetric)
-    result
+    if (child.getClass.getSimpleName == "DataWritingCommandExec") {
+      val durationMetric = longMetric("duration")
+      val innerChild = child.children.head
+      val wrappedChild = if (innerChild.getClass.getSimpleName == "WriteFilesExec") {
+        // Spark 3.4+: wrap the data plan inside WriteFilesExec
+        val dataPlan = innerChild.children.head
+        val timedDataPlan = new TimedExec.RDDTimingWrapper(dataPlan, durationMetric)
+        val wrappedWriteFiles = innerChild.withNewChildren(IndexedSeq(timedDataPlan))
+        child.withNewChildren(IndexedSeq(wrappedWriteFiles))
+      } else {
+        // Older Spark: wrap the data plan directly
+        val timedDataPlan = new TimedExec.RDDTimingWrapper(innerChild, durationMetric)
+        child.withNewChildren(IndexedSeq(timedDataPlan))
+      }
+      wrappedChild.executeCollect()
+    } else {
+      super.executeCollect()
+    }
   }
 
   override def canEqual(that: Any): Boolean = that.isInstanceOf[TimedExec]
@@ -147,9 +166,16 @@ class TimedExec(val child: SparkPlan) extends SparkPlan with CodegenSupport with
    *
    * The accumulated nanos are flushed to the SQLMetric after each produce invocation.
    * For pipelined children this happens per-row; for blocking children once after the
-   * full build phase — both are correct.
+   * full build phase.
+   *
+   * Uses try/finally so the timing flushes even when blocking operators (SortExec, etc.)
+   * exit early via shouldStop()/return — without this, duration would be 0.
    */
   override protected def doProduce(ctx: CodegenContext): String = {
+    // CodegenSupport.variablePrefix is private and falls through to nodeName.toLowerCase
+    // for unknown types (like TimedExec). Nodes with spaces in nodeName (e.g. RDDScanExec's
+    // "Scan ExistingRDD") produce invalid Java identifiers. Sanitize the prefix here.
+    ctx.freshNamePrefix = ctx.freshNamePrefix.replaceAll("[^a-zA-Z0-9_]", "")
     val durationTerm = metricTerm(ctx, "duration")
     val startTime    = ctx.freshName("timedExecStart")
     val accumulated  = ctx.addMutableState("long", ctx.freshName("timedExecAccNs"),
@@ -157,15 +183,26 @@ class TimedExec(val child: SparkPlan) extends SparkPlan with CodegenSupport with
     val childCode    = child.asInstanceOf[CodegenSupport].produce(ctx, this)
     // Test-only: inject a per-partition sleep into the generated code so tests can verify
     // that the codegen timing path actually captures wall-clock time.
+    // Uses a mutable flag so the sleep fires once per partition (not every processNext() call).
     val sleepMs = sparkContext.conf.getLong("spark.dataflint.test.codegenSleepMs", 0L)
-    val sleepCode = if (sleepMs > 0) s"try { Thread.sleep(${sleepMs}L); } catch (InterruptedException e) { }" else ""
+    val sleepCode = if (sleepMs > 0) {
+      val sleepDone = ctx.addMutableState("boolean", ctx.freshName("timedExecSleepDone"),
+        v => s"$v = false;")
+      s"""if (!$sleepDone) {
+         |  try { Thread.sleep(${sleepMs}L); } catch (InterruptedException e) { }
+         |  $sleepDone = true;
+         |}""".stripMargin
+    } else ""
     s"""
        |long $startTime = System.nanoTime();
        |$sleepCode
-       |$childCode
-       |$accumulated += System.nanoTime() - $startTime;
-       |$durationTerm.add($accumulated / $NANOS_PER_MILLIS);
-       |$accumulated = 0L;
+       |try {
+       |  $childCode
+       |} finally {
+       |  $accumulated += System.nanoTime() - $startTime;
+       |  $durationTerm.add($accumulated / $NANOS_PER_MILLIS);
+       |  $accumulated = 0L;
+       |}
      """.stripMargin
   }
 
@@ -176,4 +213,30 @@ class TimedExec(val child: SparkPlan) extends SparkPlan with CodegenSupport with
 
 object TimedExec {
   def apply(child: SparkPlan): TimedExec = new TimedExec(child)
+
+  /**
+   * A minimal SparkPlan that wraps execute() with per-partition duration timing.
+   * Used by the write path: inserted inside WriteFilesExec (or as the direct child on older
+   * Spark) so that the write command consumes a timed RDD per partition.
+   */
+  private[dataflint] class RDDTimingWrapper(val child: SparkPlan, durationMetric: SQLMetric) extends SparkPlan {
+    override def output: Seq[Attribute] = child.output
+    override def children: Seq[SparkPlan] = Seq(child)
+    override def outputPartitioning: Partitioning = child.outputPartitioning
+    override def outputOrdering: Seq[SortOrder] = child.outputOrdering
+    override def supportsColumnar: Boolean = child.supportsColumnar
+
+    override protected def doExecute(): RDD[InternalRow] =
+      DataFlintRDDUtils.withDurationMetric(child.execute(), durationMetric)
+
+    override protected def doExecuteColumnar(): RDD[ColumnarBatch] =
+      DataFlintRDDUtils.withDurationMetricColumnar(child.executeColumnar(), durationMetric)
+
+    override def productArity: Int = 1
+    override def productElement(n: Int): Any =
+      if (n == 0) child else throw new IndexOutOfBoundsException(s"$n")
+    override def canEqual(that: Any): Boolean = that.isInstanceOf[RDDTimingWrapper]
+    override protected def withNewChildrenInternal(newChildren: IndexedSeq[SparkPlan]): SparkPlan =
+      new RDDTimingWrapper(newChildren.head, durationMetric)
+  }
 }
\ No newline at end of file
diff --git a/spark-plugin/pluginspark3/src/main/scala/org/apache/spark/dataflint/DataFlintInstrumentationExtension.scala b/spark-plugin/pluginspark3/src/main/scala/org/apache/spark/dataflint/DataFlintInstrumentationExtension.scala
index f8eb04a..1d6e2ea 100644
--- a/spark-plugin/pluginspark3/src/main/scala/org/apache/spark/dataflint/DataFlintInstrumentationExtension.scala
+++ b/spark-plugin/pluginspark3/src/main/scala/org/apache/spark/dataflint/DataFlintInstrumentationExtension.scala
@@ -44,7 +44,7 @@ case class DataFlintInstrumentationColumnarRule(session: SparkSession) extends C
       "SortMergeJoinExec", "BroadcastHashJoinExec", "BroadcastNestedLoopJoinExec",
       "CartesianProductExec", "WindowGroupLimitExec", "SortAggregateExec", "SortExec", "HashAggregateExec",
       "DataWritingCommandExec",
-      "FileSourceScanExec", "RowDataSourceScanExec", "BatchScanExec",
+      "FileSourceScanExec", "RowDataSourceScanExec", "BatchScanExec", "RDDScanExec",
     )
     val all = Set(
       "BatchEvalPythonExec",
diff --git a/spark-plugin/pluginspark4/src/main/scala/org/apache/spark/dataflint/DataFlintInstrumentationExtension.scala b/spark-plugin/pluginspark4/src/main/scala/org/apache/spark/dataflint/DataFlintInstrumentationExtension.scala
index 1473091..a97ebde 100644
--- a/spark-plugin/pluginspark4/src/main/scala/org/apache/spark/dataflint/DataFlintInstrumentationExtension.scala
+++ b/spark-plugin/pluginspark4/src/main/scala/org/apache/spark/dataflint/DataFlintInstrumentationExtension.scala
@@ -36,7 +36,7 @@ case class DataFlintInstrumentationColumnarRule(session: SparkSession) extends C
       "SortMergeJoinExec", "BroadcastHashJoinExec", "BroadcastNestedLoopJoinExec",
       "CartesianProductExec", "WindowGroupLimitExec", "SortAggregateExec",
       "DataWritingCommandExec",
-      "FileSourceScanExec", "RowDataSourceScanExec", "BatchScanExec",
+      "FileSourceScanExec", "RowDataSourceScanExec", "BatchScanExec", "RDDScanExec",
     )
     val all = Set(
       "BatchEvalPythonExec",
diff --git a/spark-plugin/pyspark-testing/dataflint_pyspark_example.py b/spark-plugin/pyspark-testing/dataflint_pyspark_example.py
index 2ea8424..63fe59e 100755
--- a/spark-plugin/pyspark-testing/dataflint_pyspark_example.py
+++ b/spark-plugin/pyspark-testing/dataflint_pyspark_example.py
@@ -64,7 +64,7 @@ def sleep(seconds):
     .config("spark.plugins", "io.dataflint.spark.SparkDataflintPlugin") \
     .config("spark.ui.port", "10000") \
     .config("spark.sql.maxMetadataStringLength", "10000") \
-    .config("spark.sql.adaptive.enabled", "true") \
+    .config("spark.sql.adaptive.enabled", "false") \
     .config("spark.dataflint.telemetry.enabled", "false") \
     .config("spark.dataflint.instrument.spark.mapInPandas.enabled", instrument) \
     .config("spark.dataflint.instrument.spark.mapInArrow.enabled", instrument) \