CreateNamedStruct Expression¶

CreateNamedStruct is a <> expression that...FIXME

[[prettyName]] CreateNamedStruct uses named_struct for the <>.

[source, scala]¶

// Using Catalyst DSL import org.apache.spark.sql.catalyst.dsl.expressions._ val s = namedStruct("") scala> println(s) named_struct()

CreateNamedStruct is registered in <> under the name of named_struct SQL function.

[source, scala]¶

import org.apache.spark.sql.catalyst.FunctionIdentifier val fid = FunctionIdentifier(funcName = "named_struct") val className = spark.sessionState.functionRegistry.lookupFunction(fid).get.getClassName scala> println(className) org.apache.spark.sql.catalyst.expressions.CreateNamedStruct

val q = sql("SELECT named_struct('id', 0)") // analyzed so the function is resolved already (using FunctionRegistry) val analyzedPlan = q.queryExecution.analyzed scala> println(analyzedPlan.numberedTreeString) 00 Project [named_struct(id, 0) AS named_struct(id, 0)#7] 01 +- OneRowRelation

val e = analyzedPlan.expressions.head.children.head import org.apache.spark.sql.catalyst.expressions.CreateNamedStruct assert(e.isInstanceOf[CreateNamedStruct])

CreateNamedStruct is <> when:

• ScalaReflection, RowEncoder and JavaTypeInference are requested for a serializer of a type

• TimeWindowing and ResolveCreateNamedStruct logical resolution rules are executed

• CreateStruct is requested to <>

[[children]] [[creating-instance]] CreateNamedStruct takes a collection of <> when created.

CreateNamedStruct <>.

[source, scala]¶

// You could also use Seq("*") import org.apache.spark.sql.functions.lit val exprs = Seq("a", 1).map(lit).map(_.expr)

import org.apache.spark.sql.catalyst.expressions.CreateNamedStruct val createNamedStruct = CreateNamedStruct(exprs)

import org.apache.spark.sql.catalyst.expressions.codegen.{CodegenContext, ExprCode} val ctx = new CodegenContext // doGenCode is used when Expression.genCode is executed val ExprCode(code, _, _) = createNamedStruct.genCode(ctx)

// Helper methods def trim(code: String): String = { code.trim.split("\n").map(_.trim).filter(line => line.nonEmpty).mkString("\n") } def prettyPrint(code: String) = println(trim(code)) // END: Helper methods

scala> println(trim(code)) Object[] values_0 = new Object[1]; if (false) { values_0[0] = null; } else { values_0[0] = 1; } final InternalRow value_0 = new org.apache.spark.sql.catalyst.expressions.GenericInternalRow(values_0); values_0 = null;

[TIP]¶

Use namedStruct operator from Catalyst DSL's expressions to create a CreateNamedStruct expression.

[source, scala]¶

import org.apache.spark.sql.catalyst.dsl.expressions._ val s = namedStruct() scala> :type s org.apache.spark.sql.catalyst.expressions.Expression

import org.apache.spark.sql.catalyst.expressions.CreateNamedStruct assert(s.isInstanceOf[CreateNamedStruct])

val s = namedStruct("") scala> println(s) named_struct()

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=== [[doGenCode]] Generating Java Source Code (ExprCode) For Code-Generated Expression Evaluation -- doGenCode Method

[source, scala]¶

doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode¶

NOTE: doGenCode is part of <> to generate a Java source code (ExprCode) for code-generated expression evaluation.

doGenCode...FIXME