Thanks for opening a pull request!

Could you open an issue for this pull request on Github Issues?

https://github.com/oap-project/gluten/issues

Then could you also rename commit message and pull request title in the following format?

[GLUTEN-${ISSUES_ID}][COMPONENT]feat/fix: ${detailed message}

See also:

• Other pull requests

Run Gluten Clickhouse CI

Follow #2902, more previous discussion can be found there.

Run Gluten Clickhouse CI

Run Gluten Clickhouse CI

Run Gluten Clickhouse CI

Run Gluten Clickhouse CI

@YannByron do you have any suggestion how we can test how broken is Delta when running on Gluten/Velox?

I started an experiment, but then realized it doesn't follow the same pattern Gluten uses to test Spark. It seems we extends the existing classes and adds GlutenSQLTestsTrait, example: https://github.com/oap-project/gluten/pull/1381/files.
Should we do the same with Delta?

The experiment I started was to actually change Delta code to run the tests using Gluten:

1-) Cherry picked this to Delta 2.2. (this old workaround is not needed anymore and was messing the extension setting): delta-io/delta@975daae
2-) Added gluten to the session, at DeltaSQLCommandTest.sparkConf:

  override protected def sparkConf: SparkConf = {
    super.sparkConf
      .set(StaticSQLConf.SPARK_SESSION_EXTENSIONS.key,
        classOf[DeltaSparkSessionExtension].getName)
      .set(SQLConf.V2_SESSION_CATALOG_IMPLEMENTATION.key,
        classOf[DeltaCatalog].getName)
      .set("spark.plugins", "io.glutenproject.GlutenPlugin")
      .set("spark.gluten.sql.columnar.backend.lib", "velox")
      .set("spark.memory.offHeap.enabled", "true")
      .set("spark.memory.offHeap.size", "10g")
      .set("spark.gluten.sql.columnar.forceshuffledhashjoin", "true")
      .set("spark.shuffle.manager", "org.apache.spark.shuffle.sort.ColumnarShuffleManager")
  }

3-) Added a reference to gluten jar in libraryDependencies for delta-core.

But it it not a complete solution, most of tests are failing or not running. And the ones which passes, I can't say if they are passing because it is really working fine with Gluten/Velox, or because it falls back to non-native.

Found that _metadata is not working for Delta when column mapping is enabled.

_metadata has been recently changed to fall back: #2618

@YannByron will you work on update this PR based on discussion?

Hi, @felipepessoto, sorry for the late reply.

I run TPCDS based on delta table with gluten/velox in EMR. I use Delta 2.2 only with some internal commits (there aren't related to gluten/velox), and add the delta jar in $SPARK_HOME/jars. And the configures are same with yours except that I don't use spark.gluten.sql.columnar.backend.lib.

Found that _metadata is not working for Delta when column mapping is enabled.

I'm not really aware of this _metadata. Where to use this during querying delta in gluten/velox env? If _metadata is used in parsing delta log, i think we can ignore for now because there are other factors (like UDFs) which make parsing delta log unsupported and the time cost for this phase was low.

I think _metadata is not heavily used in 2.2, or not at all, but may be needed to replace the input_file_name UDF. In recent versions like 2.4 it is used for deletion vectors, as it needs the _metadata_row_index.

I created this repro:

class TestGluten extends QueryTest
  with SharedSparkSession with DeltaSQLCommandTest {
  test("mytest") {
    withTempDir { inputDir =>
      val testPath = inputDir.getCanonicalPath
      spark.range(10)
        .write
        .format("delta")
        .save(testPath)

      spark.sql(s""" ALTER TABLE delta.`$testPath` SET TBLPROPERTIES (
    'delta.minReaderVersion' = '2',
    'delta.minWriterVersion' = '5',
    'delta.columnMapping.mode' = 'name'
  )""")

      spark.sql(s"""SELECT id, _metadata.file_name FROM delta.`$testPath`""").show(false)
    }
  }
}

It fails because we try to replace every column, and _metadata fields are not in the mapping:

[info] - mytest *** FAILED *** (7 seconds, 852 milliseconds)
[info] java.util.NoSuchElementException: key not found: file_name
[info] at scala.collection.MapLike.default(MapLike.scala:236)
[info] at scala.collection.MapLike.default$(MapLike.scala:235)
[info] at scala.collection.AbstractMap.default(Map.scala:65)
[info] at scala.collection.mutable.HashMap.apply(HashMap.scala:69)
[info] at io.glutenproject.extension.RewritePlanIfNeeded.$anonfun$transformColumnMappingPlan$4(ColumnarOverrides.scala:109)
[info] at scala.collection.immutable.List.map(List.scala:297)
[info] at io.glutenproject.extension.RewritePlanIfNeeded.io$glutenproject$extension$RewritePlanIfNeeded$$transformColumnMappingPlan(ColumnarOverrides.scala:107)
[info] at io.glutenproject.extension.RewritePlanIfNeeded$$anonfun$apply$1.applyOrElse(ColumnarOverrides.scala:64)
[info] at io.glutenproject.extension.RewritePlanIfNeeded$$anonfun$apply$1.applyOrElse(ColumnarOverrides.scala:59)

val newAttr = o.withName(columnNameMapping(o.name))