Enum mz_expr::TraceSummary

pub enum TraceSummary {
    Constant,
    Dynamic,
    Unknown,
}

A summary type for the Trace interpreter.

The ordering of this type is meaningful: the “smaller” the summary, the more information we have about the possible values of the expression. This means we can eg. use max in the interpreter below to find the summary for a function-call expression based on the summaries of its arguments.

Variants

Constant

The expression is constant: we can evaluate it without any runtime information. This corresponds to a ResultSpec of a single value.

Dynamic

The expression depends on runtime information, but in “predictable” way… ie. if we know the range of possible values for all columns and unmaterializable functions, we can predict the possible values of the output. This corresponds to a ResultSpec of a perhaps range of values.

Unknown

The expression depends on runtime information in an unpredictable way. This corresponds to a ResultSpec::value_all() or something similarly vague.

Implementations

impl TraceSummary

fn apply_fn(self, pushdownable: bool) -> Self

We say that a function is “pushdownable” for a particular argument if ColumnSpecs can determine the spec of the function’s output given the input spec for that argument. (In practice, this is true when either the function is monotone in that argument or it’s been special-cased in the interpreter.)

pub fn pushdownable(self) -> bool

We say that an expression is “pushdownable” if it’s either constant or dynamic.

Trait Implementations

impl Clone for TraceSummary

fn clone(&self) -> TraceSummary

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for TraceSummary

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

Formats the value using the given formatter.

impl Ord for TraceSummary

fn cmp(&self, other: &TraceSummary) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized + PartialOrd,

Restrict a value to a certain interval.

impl PartialEq for TraceSummary

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for TraceSummary

fn partial_cmp(&self, other: &TraceSummary) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

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

Tests less than (for self and other) and is used by the < operator.

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

Tests less than or equal to (for self and other) and is used by the <= operator.

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

Tests greater than (for self and other) and is used by the > operator.

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

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Copy for TraceSummary

impl Eq for TraceSummary

impl StructuralPartialEq for TraceSummary