/
ComplexTypes.scala
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/
ComplexTypes.scala
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.spark.sql.catalyst.optimizer
import org.apache.spark.sql.catalyst.expressions._
import org.apache.spark.sql.catalyst.plans.logical.{Aggregate, LogicalPlan}
import org.apache.spark.sql.catalyst.rules.Rule
import org.apache.spark.sql.types.StructType
/**
* Simplify redundant [[CreateNamedStruct]], [[CreateArray]] and [[CreateMap]] expressions.
*/
object SimplifyExtractValueOps extends Rule[LogicalPlan] {
override def apply(plan: LogicalPlan): LogicalPlan = plan transform {
// One place where this optimization is invalid is an aggregation where the select
// list expression is a function of a grouping expression:
//
// SELECT struct(a,b).a FROM tbl GROUP BY struct(a,b)
//
// cannot be simplified to SELECT a FROM tbl GROUP BY struct(a,b). So just skip this
// optimization for Aggregates (although this misses some cases where the optimization
// can be made).
case a: Aggregate => a
case p => p.transformExpressionsUp {
// Remove redundant field extraction.
case GetStructField(createNamedStruct: CreateNamedStruct, ordinal, _) =>
createNamedStruct.valExprs(ordinal)
case GetStructField(u: UpdateFields, ordinal, _)if !u.structExpr.isInstanceOf[UpdateFields] =>
val structExpr = u.structExpr
u.newExprs(ordinal) match {
// if the struct itself is null, then any value extracted from it (expr) will be null
// so we don't need to wrap expr in If(IsNull(struct), Literal(null, expr.dataType), expr)
case expr: GetStructField if expr.child.semanticEquals(structExpr) => expr
case expr =>
if (structExpr.nullable) {
If(IsNull(structExpr), Literal(null, expr.dataType), expr)
} else {
expr
}
}
// Remove redundant array indexing.
case GetArrayStructFields(CreateArray(elems, useStringTypeWhenEmpty), field, ordinal, _, _) =>
// Instead of selecting the field on the entire array, select it from each member
// of the array. Pushing down the operation this way may open other optimizations
// opportunities (i.e. struct(...,x,...).x)
CreateArray(elems.map(GetStructField(_, ordinal, Some(field.name))), useStringTypeWhenEmpty)
// Remove redundant map lookup.
case ga @ GetArrayItem(CreateArray(elems, _), IntegerLiteral(idx), _) =>
// Instead of creating the array and then selecting one row, remove array creation
// altogether.
if (idx >= 0 && idx < elems.size) {
// valid index
elems(idx)
} else {
// out of bounds, mimic the runtime behavior and return null
Literal(null, ga.dataType)
}
case GetMapValue(CreateMap(elems, _), key) => CaseKeyWhen(key, elems)
}
}
}