Struct ScalarSubqueryExpr 

pub struct ScalarSubqueryExpr { /* private fields */ }

A physical expression whose value is provided by a scalar subquery.

Subquery execution is handled by ScalarSubqueryExec, which stores the result in a shared ScalarSubqueryResults container. This expression simply reads from that container at the appropriate index.

Implementations

impl ScalarSubqueryExpr

pub fn new( data_type: DataType, nullable: bool, index: SubqueryIndex, results: ScalarSubqueryResults, ) -> Self

pub fn results(&self) -> &ScalarSubqueryResults

pub fn data_type(&self) -> &DataType

👎Deprecated since 55.0.0:

was only used for proto serialization, which no longer needs it; use return_field for type/nullability. It will be removed in 61.0.0 or 6 months after 55.0.0 is released, whichever is longer.

pub fn nullable(&self) -> bool

👎Deprecated since 55.0.0:

was only used for proto serialization, which no longer needs it; use return_field for type/nullability. It will be removed in 61.0.0 or 6 months after 55.0.0 is released, whichever is longer.

pub fn index(&self) -> SubqueryIndex

👎Deprecated since 55.0.0:

was only used for proto serialization, which no longer needs it. It will be removed in 61.0.0 or 6 months after 55.0.0 is released, whichever is longer.

Returns the index of this subquery in the shared results container.

impl ScalarSubqueryExpr

pub fn try_from_proto( node: &PhysicalExprNode, _ctx: &PhysicalExprDecodeCtx<'_>, results: &ScalarSubqueryResults, ) -> Result<Arc<dyn PhysicalExpr>>

Available on crate feature proto only.

Reconstruct a ScalarSubqueryExpr from its protobuf representation.

Unlike other expressions, this takes a third argument: the shared ScalarSubqueryResults container. That container is a runtime-only Arc shared with the surrounding ScalarSubqueryExec and is not part of the wire format, so it cannot be reconstructed here or carried on the decode context (which lives in a crate that cannot depend on datafusion-expr). The match arm in from_proto.rs fetches it from the plan-level decode context and passes it in.

Trait Implementations

impl Debug for ScalarSubqueryExpr

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for ScalarSubqueryExpr

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for ScalarSubqueryExpr

impl Hash for ScalarSubqueryExpr

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for ScalarSubqueryExpr

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PhysicalExpr for ScalarSubqueryExpr

fn return_field(&self, _input_schema: &Schema) -> Result<FieldRef>

The output field associated with this expression

fn evaluate(&self, _batch: &RecordBatch) -> Result<ColumnarValue>

Evaluate an expression against a RecordBatch

fn children(&self) -> Vec<&Arc<dyn PhysicalExpr>>

Get a list of child PhysicalExpr that provide the input for this expr.

fn with_new_children( self: Arc<Self>, _children: Vec<Arc<dyn PhysicalExpr>>, ) -> Result<Arc<dyn PhysicalExpr>>

Returns a new PhysicalExpr where all children were replaced by new exprs.

fn get_properties(&self, _children: &[ExprProperties]) -> Result<ExprProperties>

Calculates the properties of this PhysicalExpr based on its children’s properties (i.e. order and range), recursively aggregating the information from its children. In cases where the PhysicalExpr has no children (e.g., Literal or Column), these properties should be specified externally, as the function defaults to unknown properties.

fn fmt_sql(&self, f: &mut Formatter<'_>) -> Result

Format this PhysicalExpr in nice human readable “SQL” format

fn try_to_proto( &self, _ctx: &PhysicalExprEncodeCtx<'_>, ) -> Result<Option<PhysicalExprNode>>

Available on crate feature proto only.

Serialize this expression to a PhysicalExprNode proto message.

fn data_type(&self, input_schema: &Schema) -> Result<DataType, DataFusionError>

Get the data type of this expression, given the schema of the input. Returns an error if the data type cannot be determined, ex. if the schema is missing a required field.

fn nullable(&self, input_schema: &Schema) -> Result<bool, DataFusionError>

Determine whether this expression is nullable, given the schema of the input

fn evaluate_selection( &self, batch: &RecordBatch, selection: &BooleanArray, ) -> Result<ColumnarValue, DataFusionError>

Evaluate an expression against a RecordBatch after first applying a validity array

fn evaluate_bounds( &self, _children: &[&Interval], ) -> Result<Interval, DataFusionError>

Computes the output interval for the expression, given the input intervals.

fn propagate_constraints( &self, _interval: &Interval, _children: &[&Interval], ) -> Result<Option<Vec<Interval>>, DataFusionError>

Updates bounds for child expressions, given a known interval for this expression.

fn evaluate_statistics( &self, children: &[&Distribution], ) -> Result<Distribution, DataFusionError>

👎Deprecated since 54.0.0:

Part of the unused Statistics V2 framework; see https://github.com/apache/datafusion/pull/22071

Computes the output statistics for the expression, given the input statistics.

fn propagate_statistics( &self, parent: &Distribution, children: &[&Distribution], ) -> Result<Option<Vec<Distribution>>, DataFusionError>

👎Deprecated since 54.0.0:

Part of the unused Statistics V2 framework; see https://github.com/apache/datafusion/pull/22071

Updates children statistics using the given parent statistic for this expression.

fn snapshot(&self) -> Result<Option<Arc<dyn PhysicalExpr>>, DataFusionError>

Take a snapshot of this PhysicalExpr, if it is dynamic.

fn snapshot_generation(&self) -> u64

Returns the generation of this PhysicalExpr for snapshotting purposes. The generation is an arbitrary u64 that can be used to track changes in the state of the PhysicalExpr over time without having to do an exhaustive comparison. This is useful to avoid unnecessary computation or serialization if there are no changes to the expression. In particular, dynamic expressions that may change over time; this allows cheap checks for changes. Static expressions that do not change over time should return 0, as does the default implementation. You should not call this method directly as it does not handle recursion. Instead use snapshot_generation to handle recursion and capture the full state of the PhysicalExpr.

fn is_volatile_node(&self) -> bool

Returns true if the expression node is volatile, i.e. whether it can return different results when evaluated multiple times with the same input.

fn placement(&self) -> ExpressionPlacement

Returns placement information for this expression.

fn expression_id(&self) -> Option<u64>

Return a stable, globally-unique identifier for this PhysicalExpr, if it has one.