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[SPARK-26450][SQL] Avoid rebuilding map of schema for every column in projection #23392

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[SPARK-26450][SQL] Avoid rebuilding map of schema for every column in projection #23392

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6b66711
Initial commit
bersprockets Dec 12, 2018
a9dbbec
Initial try at helper function
bersprockets Dec 29, 2018
67a943a
Use helper function
bersprockets Dec 31, 2018
3362744
More uses of helper function
bersprockets Dec 31, 2018
306e0a5
Even more uses of helper function
bersprockets Dec 31, 2018
a25b59c
Some clean up
bersprockets Jan 2, 2019
b977d3e
Review feedback
bersprockets Jan 2, 2019
1497d3a
Fix style issue
bersprockets Jan 2, 2019
777c5b4
Move helper function to BindReferences
bersprockets Jan 4, 2019
fbd6787
Handle cases missed before
bersprockets Jan 4, 2019
686e7b5
Review feedback
bersprockets Jan 5, 2019
b1afb3a
Close gap in ExpandExec
bersprockets Jan 13, 2019
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6 changes: 4 additions & 2 deletions ...in/scala/org/apache/spark/sql/catalyst/expressions/codegen/GenerateUnsafeProjection.scala
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Expand Up @@ -316,8 +316,10 @@ object GenerateUnsafeProjection extends CodeGenerator[Seq[Expression], UnsafePro
protected def canonicalize(in: Seq[Expression]): Seq[Expression] =
in.map(ExpressionCanonicalizer.execute)

protected def bind(in: Seq[Expression], inputSchema: Seq[Attribute]): Seq[Expression] =
in.map(BindReferences.bindReference(_, inputSchema))
protected def bind(in: Seq[Expression], inputSchema: Seq[Attribute]): Seq[Expression] = {
lazy val inputSchemaAttrSeq: AttributeSeq = inputSchema
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@hvanhovell hvanhovell Dec 28, 2018

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Why the lazy val? Are you optimizing for the case where in is empty?

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@bersprockets bersprockets Dec 28, 2018

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Yes, that is the reason. For example, the query df.count, where df is a dataframe from a CSV datasource, calls GenerateUnsafeProjection.bind with am empty list of expressions.

However, the map inside the AttributeSeq object is not built until someone accesses exprIdToOrdinal, so maybe it is overkill.

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@mgaido91 mgaido91 Dec 30, 2018 •
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what about changing the signature of bind instead? This would be helpful also to ensure that we don't miss this fix in other parts of the code IMHO.

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@bersprockets bersprockets Dec 30, 2018 •
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@mgaido91 Do you mean change it to this?:

bind(in: Seq[Expression], inputSchema: AttributeSeq): Seq[Expression]

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@mgaido91 mgaido91 Dec 30, 2018

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yes

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@hvanhovell hvanhovell Dec 30, 2018

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+1 on something that eliminates this issue wholesale.

in.map(BindReferences.bindReference(_, inputSchemaAttrSeq))
}

def generate(
expressions: Seq[Expression],
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3 changes: 2 additions & 1 deletion sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/package.scala
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Expand Up @@ -89,7 +89,8 @@ package object expressions {
* A helper function to bind given expressions to an input schema.
*/
def toBoundExprs(exprs: Seq[Expression], inputSchema: Seq[Attribute]): Seq[Expression] = {
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@mgaido91 mgaido91 Dec 30, 2018

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ditto

exprs.map(BindReferences.bindReference(_, inputSchema))
lazy val inputSchemaAttrSeq: AttributeSeq = inputSchema
exprs.map(BindReferences.bindReference(_, inputSchemaAttrSeq))
}

/**
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