$SPARK_HOME/bin/spark-shell --master local[*] --jars ${SPARK_RAPIDS_PLUGIN_JAR} --conf spark.plugins=com.nvidia.spark.SQLPlugin --conf spark.rapids.sql.enabled=true

scala> spark.conf.set("spark.sql.parquet.enableVectorizedReader", "false")

scala> val df = sql("SELECT 1.0 a, CAST(1.23 AS DECIMAL(17, 2)) b, CAST(1.23 AS DECIMAL(36, 2)) c")
df: org.apache.spark.sql.DataFrame = [a: decimal(2,1), b: decimal(17,2) ... 1 more field]

scala> df.show()
+---+----+----+
|  a|   b|   c|
+---+----+----+
|1.0|1.23|1.23|
+---+----+----+


scala> df.write.parquet("/home/fejiang/Documents/temp")

scala> val schema1 = "a DECIMAL(3, 2), b DECIMAL(18, 3), c DECIMAL(37, 3)"
schema1: String = a DECIMAL(3, 2), b DECIMAL(18, 3), c DECIMAL(37, 3)

scala> val df2 = spark.read.schema(schema1).parquet("/home/fejiang/Documents/temp")
df2: org.apache.spark.sql.DataFrame = [a: decimal(3,2), b: decimal(18,3) ... 1 more field]

scala> df2.show()
+----+-----+-----+
|   a|    b|    c|
+----+-----+-----+
|1.00|1.230|1.230|
+----+-----+-----+

scala> spark.conf.set("spark.sql.parquet.enableVectorizedReader", "false")

scala> val df = sql("SELECT 1.0 a, CAST(1.23 AS DECIMAL(17, 2)) b, CAST(1.23 AS DECIMAL(36, 2)) c")
df: org.apache.spark.sql.DataFrame = [a: decimal(2,1), b: decimal(17,2) ... 1 more field]

scala> df.show()
24/09/06 15:30:30 WARN GpuOverrides: 
  ! <RDDScanExec> cannot run on GPU because GPU does not currently support the operator class org.apache.spark.sql.execution.RDDScanExec

+---+----+----+
|  a|   b|   c|
+---+----+----+
|1.0|1.23|1.23|
+---+----+----+


scala> df.write.parquet("/home/fejiang/Documents/temp")
24/09/06 15:30:31 WARN GpuOverrides: 
    ! <RDDScanExec> cannot run on GPU because GPU does not currently support the operator class org.apache.spark.sql.execution.RDDScanExec


scala> val schema1 = "a DECIMAL(3, 2), b DECIMAL(18, 3), c DECIMAL(37, 3)"
schema1: String = a DECIMAL(3, 2), b DECIMAL(18, 3), c DECIMAL(37, 3)

scala> val df2 = spark.read.schema(schema1).parquet("/home/fejiang/Documents/temp")
df2: org.apache.spark.sql.DataFrame = [a: decimal(3,2), b: decimal(18,3) ... 1 more field]

scala> df2.show()
24/09/06 15:30:32 WARN GpuOverrides: 
!Exec <CollectLimitExec> cannot run on GPU because the Exec CollectLimitExec has been disabled, and is disabled by default because Collect Limit replacement can be slower on the GPU, if huge number of rows in a batch it could help by limiting the number of rows transferred from GPU to CPU. Set spark.rapids.sql.exec.CollectLimitExec to true if you wish to enable it
  @Partitioning <SinglePartition$> could run on GPU

24/09/06 15:30:32 ERROR Executor: Exception in task 0.0 in stage 3.0 (TID 3)
org.apache.spark.sql.execution.QueryExecutionException: Parquet column cannot be converted in file file:///home/fejiang/Documents/temp/part-00000-9f83dfb2-74c0-4b2a-9bd4-5faadaeb893d-c000.snappy.parquet. Column: a, Expected: decimal(3,2), Found: required int32 a (DECIMAL(2,1))
	at com.nvidia.spark.rapids.GpuParquetFileFilterHandler.throwTypeIncompatibleError(GpuParquetScan.scala:1025)
	at com.nvidia.spark.rapids.GpuParquetFileFilterHandler.$anonfun$filterBlocks$12(GpuParquetScan.scala:757)
	at com.nvidia.spark.rapids.GpuParquetFileFilterHandler.$anonfun$filterBlocks$12$adapted(GpuParquetScan.scala:757)
	at com.nvidia.spark.rapids.GpuParquetFileFilterHandler.$anonfun$checkSchemaCompat$6(GpuParquetScan.scala:878)
	at com.nvidia.spark.rapids.GpuParquetFileFilterHandler.checkPrimitiveCompat(GpuParquetScan.scala:1009)
	at com.nvidia.spark.rapids.GpuParquetFileFilterHandler.checkSchemaCompat(GpuParquetScan.scala:878)
	at com.nvidia.spark.rapids.GpuParquetFileFilterHandler.$anonfun$checkSchemaCompat$3(GpuParquetScan.scala:830)
	at com.nvidia.spark.rapids.GpuParquetFileFilterHandler.$anonfun$checkSchemaCompat$3$adapted(GpuParquetScan.scala:821)
	at scala.Option.foreach(Option.scala:407)
	at com.nvidia.spark.rapids.GpuParquetFileFilterHandler.$anonfun$checkSchemaCompat$2(GpuParquetScan.scala:821)
	at com.nvidia.spark.rapids.GpuParquetFileFilterHandler.$anonfun$checkSchemaCompat$2$adapted(GpuParquetScan.scala:820)
	at scala.collection.IndexedSeqOptimized.foreach(IndexedSeqOptimized.scala:36)
	at scala.collection.IndexedSeqOptimized.foreach$(IndexedSeqOptimized.scala:33)