Class

org.apache.spark.sql.catalyst.expressions

Alias

Related Doc: package expressions

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case class Alias(child: Expression, name: String)(exprId: ExprId = NamedExpression.newExprId, qualifier: Option[String] = None, explicitMetadata: Option[Metadata] = None, isGenerated: Boolean = false) extends UnaryExpression with NamedExpression with Product with Serializable

Used to assign a new name to a computation. For example the SQL expression "1 + 1 AS a" could be represented as follows: Alias(Add(Literal(1), Literal(1)), "a")()

Note that exprId and qualifiers are in a separate parameter list because we only pattern match on child and name.

child

The computation being performed

name

The name to be associated with the result of computing child.

exprId

A globally unique id used to check if an AttributeReference refers to this alias. Auto-assigned if left blank.

qualifier

An optional string that can be used to referred to this attribute in a fully qualified way. Consider the examples tableName.name, subQueryAlias.name. tableName and subQueryAlias are possible qualifiers.

explicitMetadata

Explicit metadata associated with this alias that overwrites child's.

isGenerated

A flag to indicate if this alias is generated by Catalyst

Linear Supertypes
Serializable, Serializable, NamedExpression, UnaryExpression, Expression, TreeNode[Expression], Product, Equals, AnyRef, Any
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Inherited
  1. Alias
  2. Serializable
  3. Serializable
  4. NamedExpression
  5. UnaryExpression
  6. Expression
  7. TreeNode
  8. Product
  9. Equals
  10. AnyRef
  11. Any
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Visibility
  1. Public
  2. All

Instance Constructors

  1. new Alias(child: Expression, name: String)(exprId: ExprId = NamedExpression.newExprId, qualifier: Option[String] = None, explicitMetadata: Option[Metadata] = None, isGenerated: Boolean = false)

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    child

    The computation being performed

    name

    The name to be associated with the result of computing child.

    exprId

    A globally unique id used to check if an AttributeReference refers to this alias. Auto-assigned if left blank.

    qualifier

    An optional string that can be used to referred to this attribute in a fully qualified way. Consider the examples tableName.name, subQueryAlias.name. tableName and subQueryAlias are possible qualifiers.

    explicitMetadata

    Explicit metadata associated with this alias that overwrites child's.

    isGenerated

    A flag to indicate if this alias is generated by Catalyst

Value Members

  1. final def !=(arg0: Any): Boolean

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    Definition Classes
    AnyRef → Any
  2. final def ##(): Int

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    Definition Classes
    AnyRef → Any
  3. final def ==(arg0: Any): Boolean

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    Definition Classes
    AnyRef → Any
  4. def apply(number: Int): TreeNode[_]

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    Returns the tree node at the specified number, used primarily for interactive debugging.

    Returns the tree node at the specified number, used primarily for interactive debugging. Numbers for each node can be found in the numberedTreeString.

    Note that this cannot return BaseType because logical plan's plan node might return physical plan for innerChildren, e.g. in-memory relation logical plan node has a reference to the physical plan node it is referencing.

    Definition Classes
    TreeNode
  5. def argString: String

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    Returns a string representing the arguments to this node, minus any children

    Returns a string representing the arguments to this node, minus any children

    Definition Classes
    TreeNode
  6. def asCode: String

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    Returns a 'scala code' representation of this TreeNode and its children.

    Returns a 'scala code' representation of this TreeNode and its children. Intended for use when debugging where the prettier toString function is obfuscating the actual structure. In the case of 'pure' TreeNodes that only contain primitives and other TreeNodes, the result can be pasted in the REPL to build an equivalent Tree.

    Definition Classes
    TreeNode
  7. final def asInstanceOf[T0]: T0

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    Definition Classes
    Any
  8. lazy val canonicalized: Expression

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    Returns an expression where a best effort attempt has been made to transform this in a way that preserves the result but removes cosmetic variations (case sensitivity, ordering for commutative operations, etc.) See Canonicalize for more details.

    Returns an expression where a best effort attempt has been made to transform this in a way that preserves the result but removes cosmetic variations (case sensitivity, ordering for commutative operations, etc.) See Canonicalize for more details.

    deterministic expressions where this.canonicalized == other.canonicalized will always evaluate to the same result.

    Definition Classes
    Expression
  9. def checkInputDataTypes(): TypeCheckResult

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    Checks the input data types, returns TypeCheckResult.success if it's valid, or returns a TypeCheckResult with an error message if invalid.

    Checks the input data types, returns TypeCheckResult.success if it's valid, or returns a TypeCheckResult with an error message if invalid. Note: it's not valid to call this method until childrenResolved == true.

    Definition Classes
    Expression
  10. val child: Expression

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    The computation being performed

    The computation being performed

    Definition Classes
    AliasUnaryExpression
  11. final def children: Seq[Expression]

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    Returns a Seq of the children of this node.

    Returns a Seq of the children of this node. Children should not change. Immutability required for containsChild optimization

    Definition Classes
    UnaryExpressionTreeNode
  12. def childrenResolved: Boolean

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    Returns true if all the children of this expression have been resolved to a specific schema and false if any still contains any unresolved placeholders.

    Returns true if all the children of this expression have been resolved to a specific schema and false if any still contains any unresolved placeholders.

    Definition Classes
    Expression
  13. def clone(): AnyRef

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    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  14. def collect[B](pf: PartialFunction[Expression, B]): Seq[B]

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    Returns a Seq containing the result of applying a partial function to all elements in this tree on which the function is defined.

    Returns a Seq containing the result of applying a partial function to all elements in this tree on which the function is defined.

    Definition Classes
    TreeNode
  15. def collectFirst[B](pf: PartialFunction[Expression, B]): Option[B]

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    Finds and returns the first TreeNode of the tree for which the given partial function is defined (pre-order), and applies the partial function to it.

    Finds and returns the first TreeNode of the tree for which the given partial function is defined (pre-order), and applies the partial function to it.

    Definition Classes
    TreeNode
  16. def collectLeaves(): Seq[Expression]

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    Returns a Seq containing the leaves in this tree.

    Returns a Seq containing the leaves in this tree.

    Definition Classes
    TreeNode
  17. lazy val containsChild: Set[TreeNode[_]]

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    Definition Classes
    TreeNode
  18. def dataType: DataType

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    Returns the DataType of the result of evaluating this expression.

    Returns the DataType of the result of evaluating this expression. It is invalid to query the dataType of an unresolved expression (i.e., when resolved == false).

    Definition Classes
    AliasExpression
  19. def defineCodeGen(ctx: CodegenContext, ev: ExprCode, f: (String) ⇒ String): ExprCode

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    Called by unary expressions to generate a code block that returns null if its parent returns null, and if not null, use f to generate the expression.

    Called by unary expressions to generate a code block that returns null if its parent returns null, and if not null, use f to generate the expression.

    As an example, the following does a boolean inversion (i.e. NOT).

    defineCodeGen(ctx, ev, c => s"!($c)")
    f

    function that accepts a variable name and returns Java code to compute the output.

    Attributes
    protected
    Definition Classes
    UnaryExpression
  20. def deterministic: Boolean

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    Returns true when the current expression always return the same result for fixed inputs from children.

    Returns true when the current expression always return the same result for fixed inputs from children.

    Note that this means that an expression should be considered as non-deterministic if: - it relies on some mutable internal state, or - it relies on some implicit input that is not part of the children expression list. - it has non-deterministic child or children.

    An example would be SparkPartitionID that relies on the partition id returned by TaskContext. By default leaf expressions are deterministic as Nil.forall(_.deterministic) returns true.

    Definition Classes
    Expression
  21. def doGenCode(ctx: CodegenContext, ev: ExprCode): ExprCode

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    Returns Java source code that can be compiled to evaluate this expression.

    Returns Java source code that can be compiled to evaluate this expression. The default behavior is to call the eval method of the expression. Concrete expression implementations should override this to do actual code generation.

    ctx

    a CodegenContext

    ev

    an ExprCode with unique terms.

    returns

    an ExprCode containing the Java source code to generate the given expression

    Attributes
    protected
    Definition Classes
    AliasExpression
  22. final def eq(arg0: AnyRef): Boolean

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    Definition Classes
    AnyRef
  23. def equals(other: Any): Boolean

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    Definition Classes
    Alias → Equals → AnyRef → Any
  24. def eval(input: InternalRow): Any

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    Default behavior of evaluation according to the default nullability of UnaryExpression.

    Default behavior of evaluation according to the default nullability of UnaryExpression. If subclass of UnaryExpression override nullable, probably should also override this.

    Definition Classes
    AliasUnaryExpressionExpression
  25. val explicitMetadata: Option[Metadata]

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    Explicit metadata associated with this alias that overwrites child's.

  26. val exprId: ExprId

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    A globally unique id used to check if an AttributeReference refers to this alias.

    A globally unique id used to check if an AttributeReference refers to this alias. Auto-assigned if left blank.

    Definition Classes
    AliasNamedExpression
  27. def fastEquals(other: TreeNode[_]): Boolean

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    Faster version of equality which short-circuits when two treeNodes are the same instance.

    Faster version of equality which short-circuits when two treeNodes are the same instance. We don't just override Object.equals, as doing so prevents the scala compiler from generating case class equals methods

    Definition Classes
    TreeNode
  28. def finalize(): Unit

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    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
  29. def find(f: (Expression) ⇒ Boolean): Option[Expression]

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    Find the first TreeNode that satisfies the condition specified by f.

    Find the first TreeNode that satisfies the condition specified by f. The condition is recursively applied to this node and all of its children (pre-order).

    Definition Classes
    TreeNode
  30. def flatArguments: Iterator[Any]

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    Attributes
    protected
    Definition Classes
    Expression
  31. def flatMap[A](f: (Expression) ⇒ TraversableOnce[A]): Seq[A]

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    Returns a Seq by applying a function to all nodes in this tree and using the elements of the resulting collections.

    Returns a Seq by applying a function to all nodes in this tree and using the elements of the resulting collections.

    Definition Classes
    TreeNode
  32. def foldable: Boolean

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    We should never fold named expressions in order to not remove the alias.

    We should never fold named expressions in order to not remove the alias.

    Definition Classes
    NamedExpressionExpression
  33. def foreach(f: (Expression) ⇒ Unit): Unit

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    Runs the given function on this node and then recursively on children.

    Runs the given function on this node and then recursively on children.

    f

    the function to be applied to each node in the tree.

    Definition Classes
    TreeNode
  34. def foreachUp(f: (Expression) ⇒ Unit): Unit

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    Runs the given function recursively on children then on this node.

    Runs the given function recursively on children then on this node.

    f

    the function to be applied to each node in the tree.

    Definition Classes
    TreeNode
  35. def genCode(ctx: CodegenContext): ExprCode

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    Just a simple passthrough for code generation.

    Just a simple passthrough for code generation.

    ctx

    a CodegenContext

    returns

    ExprCode

    Definition Classes
    AliasExpression
  36. def generateTreeString(depth: Int, lastChildren: Seq[Boolean], builder: StringBuilder, verbose: Boolean, prefix: String = "", addSuffix: Boolean = false): StringBuilder

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    Appends the string represent of this node and its children to the given StringBuilder.

    Appends the string represent of this node and its children to the given StringBuilder.

    The i-th element in lastChildren indicates whether the ancestor of the current node at depth i + 1 is the last child of its own parent node. The depth of the root node is 0, and lastChildren for the root node should be empty.

    Note that this traversal (numbering) order must be the same as getNodeNumbered.

    Definition Classes
    TreeNode
  37. final def getClass(): Class[_]

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    Definition Classes
    AnyRef → Any
  38. def hashCode(): Int

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    Definition Classes
    AliasTreeNode → AnyRef → Any
  39. def innerChildren: Seq[TreeNode[_]]

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    All the nodes that should be shown as a inner nested tree of this node.

    All the nodes that should be shown as a inner nested tree of this node. For example, this can be used to show sub-queries.

    Attributes
    protected
    Definition Classes
    TreeNode
  40. val isGenerated: Boolean

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    A flag to indicate if this alias is generated by Catalyst

    A flag to indicate if this alias is generated by Catalyst

    Definition Classes
    AliasNamedExpression
  41. final def isInstanceOf[T0]: Boolean

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    Definition Classes
    Any
  42. def jsonFields: List[JField]

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    Attributes
    protected
    Definition Classes
    TreeNode
  43. def makeCopy(newArgs: Array[AnyRef]): Expression

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    Creates a copy of this type of tree node after a transformation.

    Creates a copy of this type of tree node after a transformation. Must be overridden by child classes that have constructor arguments that are not present in the productIterator.

    newArgs

    the new product arguments.

    Definition Classes
    TreeNode
  44. def map[A](f: (Expression) ⇒ A): Seq[A]

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    Returns a Seq containing the result of applying the given function to each node in this tree in a preorder traversal.

    Returns a Seq containing the result of applying the given function to each node in this tree in a preorder traversal.

    f

    the function to be applied.

    Definition Classes
    TreeNode
  45. def mapChildren(f: (Expression) ⇒ Expression): Expression

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    Returns a copy of this node where f has been applied to all the nodes children.

    Returns a copy of this node where f has been applied to all the nodes children.

    Definition Classes
    TreeNode
  46. def mapProductIterator[B](f: (Any) ⇒ B)(implicit arg0: ClassTag[B]): Array[B]

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    Efficient alternative to productIterator.map(f).toArray.

    Efficient alternative to productIterator.map(f).toArray.

    Attributes
    protected
    Definition Classes
    TreeNode
  47. def metadata: Metadata

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    Returns the metadata when an expression is a reference to another expression with metadata.

    Returns the metadata when an expression is a reference to another expression with metadata.

    Definition Classes
    AliasNamedExpression
  48. val name: String

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    The name to be associated with the result of computing child.

    The name to be associated with the result of computing child.

    Definition Classes
    AliasNamedExpression
  49. final def ne(arg0: AnyRef): Boolean

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    Definition Classes
    AnyRef
  50. def newInstance(): NamedExpression

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    Returns a copy of this expression with a new exprId.

    Returns a copy of this expression with a new exprId.

    Definition Classes
    AliasNamedExpression
  51. def nodeName: String

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    Returns the name of this type of TreeNode.

    Returns the name of this type of TreeNode. Defaults to the class name. Note that we remove the "Exec" suffix for physical operators here.

    Definition Classes
    TreeNode
  52. final def notify(): Unit

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    Definition Classes
    AnyRef
  53. final def notifyAll(): Unit

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    Definition Classes
    AnyRef
  54. def nullSafeCodeGen(ctx: CodegenContext, ev: ExprCode, f: (String) ⇒ String): ExprCode

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    Called by unary expressions to generate a code block that returns null if its parent returns null, and if not null, use f to generate the expression.

    Called by unary expressions to generate a code block that returns null if its parent returns null, and if not null, use f to generate the expression.

    f

    function that accepts the non-null evaluation result name of child and returns Java code to compute the output.

    Attributes
    protected
    Definition Classes
    UnaryExpression
  55. def nullSafeEval(input: Any): Any

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    Called by default eval implementation.

    Called by default eval implementation. If subclass of UnaryExpression keep the default nullability, they can override this method to save null-check code. If we need full control of evaluation process, we should override eval.

    Attributes
    protected
    Definition Classes
    UnaryExpression
  56. def nullable: Boolean

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    Definition Classes
    AliasUnaryExpressionExpression
  57. def numberedTreeString: String

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    Returns a string representation of the nodes in this tree, where each operator is numbered.

    Returns a string representation of the nodes in this tree, where each operator is numbered. The numbers can be used with TreeNode.apply to easily access specific subtrees.

    The numbers are based on depth-first traversal of the tree (with innerChildren traversed first before children).

    Definition Classes
    TreeNode
  58. val origin: Origin

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    Definition Classes
    TreeNode
  59. final def otherCopyArgs: Seq[AnyRef]

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    Args to the constructor that should be copied, but not transformed.

    Args to the constructor that should be copied, but not transformed. These are appended to the transformed args automatically by makeCopy

    Attributes
    protected
    Definition Classes
    AliasTreeNode
  60. def p(number: Int): Expression

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    Returns the tree node at the specified number, used primarily for interactive debugging.

    Returns the tree node at the specified number, used primarily for interactive debugging. Numbers for each node can be found in the numberedTreeString.

    This is a variant of apply that returns the node as BaseType (if the type matches).

    Definition Classes
    TreeNode
  61. def prettyJson: String

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    Definition Classes
    TreeNode
  62. def prettyName: String

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    Returns a user-facing string representation of this expression's name.

    Returns a user-facing string representation of this expression's name. This should usually match the name of the function in SQL.

    Definition Classes
    Expression
  63. def qualifiedName: String

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    Returns a dot separated fully qualified name for this attribute.

    Returns a dot separated fully qualified name for this attribute. Given that there can be multiple qualifiers, it is possible that there are other possible way to refer to this attribute.

    Definition Classes
    NamedExpression
  64. val qualifier: Option[String]

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    An optional string that can be used to referred to this attribute in a fully qualified way.

    An optional string that can be used to referred to this attribute in a fully qualified way. Consider the examples tableName.name, subQueryAlias.name. tableName and subQueryAlias are possible qualifiers.

    Definition Classes
    AliasNamedExpression
  65. def references: AttributeSet

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    Definition Classes
    Expression
  66. lazy val resolved: Boolean

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    Returns true if this expression and all its children have been resolved to a specific schema and input data types checking passed, and false if it still contains any unresolved placeholders or has data types mismatch.

    Returns true if this expression and all its children have been resolved to a specific schema and input data types checking passed, and false if it still contains any unresolved placeholders or has data types mismatch. Implementations of expressions should override this if the resolution of this type of expression involves more than just the resolution of its children and type checking.

    Definition Classes
    AliasExpression
  67. def semanticEquals(other: Expression): Boolean

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    Returns true when two expressions will always compute the same result, even if they differ cosmetically (i.e.

    Returns true when two expressions will always compute the same result, even if they differ cosmetically (i.e. capitalization of names in attributes may be different).

    See Canonicalize for more details.

    Definition Classes
    Expression
  68. def semanticHash(): Int

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    Returns a hashCode for the calculation performed by this expression.

    Returns a hashCode for the calculation performed by this expression. Unlike the standard hashCode, an attempt has been made to eliminate cosmetic differences.

    See Canonicalize for more details.

    Definition Classes
    Expression
  69. def simpleString: String

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    ONE line description of this node.

    ONE line description of this node.

    Definition Classes
    ExpressionTreeNode
  70. def sql: String

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    Returns SQL representation of this expression.

    Returns SQL representation of this expression. For expressions extending NonSQLExpression, this method may return an arbitrary user facing string.

    Definition Classes
    AliasExpression
  71. def stringArgs: Iterator[Any]

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    The arguments that should be included in the arg string.

    The arguments that should be included in the arg string. Defaults to the productIterator.

    Attributes
    protected
    Definition Classes
    TreeNode
  72. final def synchronized[T0](arg0: ⇒ T0): T0

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    Definition Classes
    AnyRef
  73. def toAttribute: Attribute

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    Definition Classes
    AliasNamedExpression
  74. def toJSON: String

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    Definition Classes
    TreeNode
  75. def toString(): String

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    Definition Classes
    AliasExpressionTreeNode → AnyRef → Any
  76. def transform(rule: PartialFunction[Expression, Expression]): Expression

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    Returns a copy of this node where rule has been recursively applied to the tree.

    Returns a copy of this node where rule has been recursively applied to the tree. When rule does not apply to a given node it is left unchanged. Users should not expect a specific directionality. If a specific directionality is needed, transformDown or transformUp should be used.

    rule

    the function use to transform this nodes children

    Definition Classes
    TreeNode
  77. def transformDown(rule: PartialFunction[Expression, Expression]): Expression

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    Returns a copy of this node where rule has been recursively applied to it and all of its children (pre-order).

    Returns a copy of this node where rule has been recursively applied to it and all of its children (pre-order). When rule does not apply to a given node it is left unchanged.

    rule

    the function used to transform this nodes children

    Definition Classes
    TreeNode
  78. def transformUp(rule: PartialFunction[Expression, Expression]): Expression

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    Returns a copy of this node where rule has been recursively applied first to all of its children and then itself (post-order).

    Returns a copy of this node where rule has been recursively applied first to all of its children and then itself (post-order). When rule does not apply to a given node, it is left unchanged.

    rule

    the function use to transform this nodes children

    Definition Classes
    TreeNode
  79. def treeString(verbose: Boolean, addSuffix: Boolean = false): String

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    Definition Classes
    TreeNode
  80. def treeString: String

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    Returns a string representation of the nodes in this tree

    Returns a string representation of the nodes in this tree

    Definition Classes
    TreeNode
  81. def typeSuffix: String

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    Attributes
    protected
    Definition Classes
    NamedExpression
  82. final def verboseString: String

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    ONE line description of this node with more information

    ONE line description of this node with more information

    Definition Classes
    ExpressionTreeNode
  83. def verboseStringWithSuffix: String

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    ONE line description of this node with some suffix information

    ONE line description of this node with some suffix information

    Definition Classes
    TreeNode
  84. final def wait(): Unit

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    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  85. final def wait(arg0: Long, arg1: Int): Unit

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    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  86. final def wait(arg0: Long): Unit

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    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  87. def withNewChildren(newChildren: Seq[Expression]): Expression

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    Returns a copy of this node with the children replaced.

    Returns a copy of this node with the children replaced. TODO: Validate somewhere (in debug mode?) that children are ordered correctly.

    Definition Classes
    TreeNode

Inherited from Serializable

Inherited from Serializable

Inherited from NamedExpression

Inherited from UnaryExpression

Inherited from Expression

Inherited from TreeNode[Expression]

Inherited from Product

Inherited from Equals

Inherited from AnyRef

Inherited from Any

Ungrouped