philo-he commented on code in PR #12675: URL: https://github.com/apache/gluten/pull/12675#discussion_r3706838954
########## docs/velox-backend-limitations.md: ########## @@ -144,17 +144,10 @@ Gluten's. Only reading with INT96 and dictionary encoding is supported. When reading INT64 represented millisecond/microsecond timestamps, or INT96 represented timestamps of other encodings, exceptions can occur. -- Complex types - - Parquet scan of nested array with struct or array as element type is not supported in Velox (fallback behavior). - - Parquet scan of nested map with struct as key type, or array type as value type is not supported in Velox (fallback behavior). - -### CSV Read -The header option should be true. And now we only support DatasourceV1, i.e., user should set `spark.sql.sources.useV1SourceList=csv`. User defined read option is not supported, which will make CSV read fall back to vanilla Spark in most case. -CSV read will also fall back to vanilla Spark and log warning when user specifies schema is different with file schema. - ### Utilizing Map Type as Hash Keys in ColumnarShuffleExchange -Spark uses the `spark.sql.legacy.allowHashOnMapType` configuration to support hash map key functions. -Gluten enables this configuration during the creation of ColumnarShuffleExchange, as shown in the code [link](https://github.com/apache/gluten/blob/0dacac84d3bf3d2759a5dd7e0735147852d2845d/backends-velox/src/main/scala/org/apache/gluten/backendsapi/velox/VeloxSparkPlanExecApi.scala#L355-L363). -This method bypasses Spark's unresolved checks and creates projects with the hash(mapType) operator before ColumnarShuffleExchange. -However, if `spark.sql.legacy.allowHashOnMapType` is disabled in a test environment, projects using the hash(mapType) expression may throw an `Invalid call to dataType on unresolved object` exception during validation, causing them to fallback to vanilla Spark, as referenced in the code [link](https://github.com/apache/spark/blob/de5fa426e23b84fc3c2bddeabcd2e1eda515abd5/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/hash.scala#L291-L296). - Enabling this configuration allows the project to be offloaded to Velox. +Spark's `spark.sql.legacy.allowHashOnMapType` configuration controls whether hashing is allowed on map-type keys. +Gluten enables this configuration when creating `ColumnarShuffleExchange`, as shown [here](https://github.com/apache/gluten/blob/0dacac84d3bf3d2759a5dd7e0735147852d2845d/backends-velox/src/main/scala/org/apache/gluten/backendsapi/velox/VeloxSparkPlanExecApi.scala#L355-L363). Review Comment: Just updated the PR description, this "CSV Read" section is not valid now because the CSV reader has been removed from the code. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
