32cfd3e75a
## What changes were proposed in this pull request?
Current code block manipulation API is immature and hacky. We need a formal API to manipulate code blocks.
The basic idea is making `JavaCode` as `TreeNode`. So we can use familiar `transform` API to manipulate code blocks and expressions in code blocks.
For example, we can replace `SimpleExprValue` in a code block like this:
```scala
code.transformExprValues {
case SimpleExprValue("1 + 1", _) => aliasedParam
}
```
The example use case is splitting code to methods.
For example, we have an `ExprCode` containing generated code. But it is too long and we need to split it as method. Because statement-based expressions can't be directly passed into. We need to transform them as variables first:
```scala
def getExprValues(block: Block): Set[ExprValue] = block match {
case c: CodeBlock =>
c.blockInputs.collect {
case e: ExprValue => e
}.toSet
case _ => Set.empty
}
def currentCodegenInputs(ctx: CodegenContext): Set[ExprValue] = {
// Collects current variables in ctx.currentVars and ctx.INPUT_ROW.
// It looks roughly like...
ctx.currentVars.flatMap { v =>
getExprValues(v.code) ++ Set(v.value, v.isNull)
}.toSet + ctx.INPUT_ROW
}
// A code block of an expression contains too long code, making it as method
if (eval.code.length > 1024) {
val setIsNull = if (!eval.isNull.isInstanceOf[LiteralValue]) {
...
} else {
""
}
// Pick up variables and statements necessary to pass in.
val currentVars = currentCodegenInputs(ctx)
val varsPassIn = getExprValues(eval.code).intersect(currentVars)
val aliasedExprs = HashMap.empty[SimpleExprValue, VariableValue]
// Replace statement-based expressions which can't be directly passed in the method.
val newCode = eval.code.transform {
case block =>
block.transformExprValues {
case s: SimpleExprValue(_, javaType) if varsPassIn.contains(s) =>
if (aliasedExprs.contains(s)) {
aliasedExprs(s)
} else {
val aliasedVariable = JavaCode.variable(ctx.freshName("aliasedVar"), javaType)
aliasedExprs += s -> aliasedVariable
varsPassIn += aliasedVariable
aliasedVariable
}
}
}
val params = varsPassIn.filter(!_.isInstanceOf[SimpleExprValue])).map { variable =>
s"${variable.javaType.getName} ${variable.variableName}"
}.mkString(", ")
val funcName = ctx.freshName("nodeName")
val javaType = CodeGenerator.javaType(dataType)
val newValue = JavaCode.variable(ctx.freshName("value"), dataType)
val funcFullName = ctx.addNewFunction(funcName,
s"""
|private $javaType $funcName($params) {
| $newCode
| $setIsNull
| return ${eval.value};
|}
""".stripMargin))
eval.value = newValue
val args = varsPassIn.filter(!_.isInstanceOf[SimpleExprValue])).map { variable =>
s"${variable.variableName}"
}
// Create a code block to assign statements to aliased variables.
val createVariables = aliasedExprs.foldLeft(EmptyBlock) { (block, (statement, variable)) =>
block + code"${statement.javaType.getName} $variable = $statement;"
}
eval.code = createVariables + code"$javaType $newValue = $funcFullName($args);"
}
```
## How was this patch tested?
Added unite tests.
Author: Liang-Chi Hsieh <viirya@gmail.com>
Closes #21405 from viirya/codeblock-api.
|
||
|---|---|---|
| .. | ||
| catalyst | ||
| core | ||
| hive | ||
| hive-thriftserver | ||
| create-docs.sh | ||
| gen-sql-markdown.py | ||
| mkdocs.yml | ||
| README.md | ||
Spark SQL
This module provides support for executing relational queries expressed in either SQL or the DataFrame/Dataset API.
Spark SQL is broken up into four subprojects:
- Catalyst (sql/catalyst) - An implementation-agnostic framework for manipulating trees of relational operators and expressions.
- Execution (sql/core) - A query planner / execution engine for translating Catalyst's logical query plans into Spark RDDs. This component also includes a new public interface, SQLContext, that allows users to execute SQL or LINQ statements against existing RDDs and Parquet files.
- Hive Support (sql/hive) - Includes an extension of SQLContext called HiveContext that allows users to write queries using a subset of HiveQL and access data from a Hive Metastore using Hive SerDes. There are also wrappers that allow users to run queries that include Hive UDFs, UDAFs, and UDTFs.
- HiveServer and CLI support (sql/hive-thriftserver) - Includes support for the SQL CLI (bin/spark-sql) and a HiveServer2 (for JDBC/ODBC) compatible server.
Running sql/create-docs.sh generates SQL documentation for built-in functions under sql/site.