[SPARK-50615][SQL] Push variant into scan. #49235
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@cloud-fan @gene-db @cashmand Please help review, thanks! |
cloud-fan
reviewed
Dec 19, 2024
| @@ -95,7 +95,8 @@ class SparkOptimizer( | |||
| EliminateLimits, | |||
| ConstantFolding), | |||
| Batch("User Provided Optimizers", fixedPoint, experimentalMethods.extraOptimizations: _*), | |||
| Batch("Replace CTE with Repartition", Once, ReplaceCTERefWithRepartition))) | |||
| Batch("Replace CTE with Repartition", Once, ReplaceCTERefWithRepartition), | |||
| Batch("Push Variant Into Scan", Once, PushVariantIntoScan))) | |||
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why does this rule need to be in the end of optimizer?
cloud-fan
reviewed
Dec 19, 2024
Comment on lines
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| def addVariantFields(attrId: ExprId, dataType: DataType, defaultValue: Any, | ||
| path: Seq[Int]): Unit = { |
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Suggested change
| def addVariantFields(attrId: ExprId, dataType: DataType, defaultValue: Any, | |
| path: Seq[Int]): Unit = { | |
| def addVariantFields( | |
| attrId: ExprId, | |
| dataType: DataType, | |
| defaultValue: Any, | |
| path: Seq[Int]): Unit = { |
cloud-fan
reviewed
Dec 19, 2024
Comment on lines
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| private def addField(map: HashMap[RequestedVariantField, Int], | ||
| field: RequestedVariantField): Unit = { |
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Suggested change
| private def addField(map: HashMap[RequestedVariantField, Int], | |
| field: RequestedVariantField): Unit = { | |
| private def addField( | |
| map: HashMap[RequestedVariantField, Int], | |
| field: RequestedVariantField): Unit = { |
cloud-fan
reviewed
Dec 19, 2024
| } | ||
| } | ||
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| private def rewritePlan(originalPlan: LogicalPlan, |
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ditto, fix indentaiton please
cloud-fan
reviewed
Dec 19, 2024
| // - Filter [v.0 = 1] | ||
| // - Relation [v: struct<0: int, 1: string, 2: variant>] | ||
| // The struct fields are annotated with `VariantMetadata` to indicate the extraction path. | ||
| object PushVariantIntoScan extends Rule[LogicalPlan] { |
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This rule matches a similar plan pattern as SchemaPruning, shall we also put this rule in the earlyScanPushDownRules of SparkOptimizer?
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@cloud-fan Thanks! I have made the changes you recommended. |
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thanks, merging to master! |
cloud-fan
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Dec 24, 2024
### What changes were proposed in this pull request? It adds support for variant struct in Parquet reader. The concept of variant struct was introduced in #49235. It includes all the extracted fields from a variant column that the query requests. ### Why are the changes needed? By producing variant struct in Parquet reader, we can avoid reading/rebuilding the full variant and achieve more efficient variant processing. ### Does this PR introduce _any_ user-facing change? No. ### How was this patch tested? Unit test. ### Was this patch authored or co-authored using generative AI tooling? No. Closes #49263 from chenhao-db/spark_variant_struct_reader. Authored-by: Chenhao Li <chenhao.li@databricks.com> Signed-off-by: Wenchen Fan <wenchen@databricks.com>
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What changes were proposed in this pull request?
It adds an optimizer rule to push variant into scan by rewriting the variant type with a struct type producing all requested fields and rewriting the variant extraction expressions by struct accesses. This will be the foundation of the variant shredding reader. The rule must be disabled at this point because the scan part is not yet able to recognize the special struct.
Why are the changes needed?
It is necessary for the performance of reading from shredded variant. With this rule (and the reader implemented), the scan only needs to fetch the necessary shredded columns required by the plan.
Does this PR introduce any user-facing change?
No.
How was this patch tested?
Unit test.
Was this patch authored or co-authored using generative AI tooling?
No.