Struct JoinCoverageConstraint 

pub struct JoinCoverageConstraint { /* private fields */ }

Join coverage constraint for validating the quality of table joins.

This constraint measures what percentage of rows from the left table successfully join with the right table, helping identify:

• Missing reference data
• Data quality issues in foreign key relationships
• Incomplete data loads
• Orphaned records

The constraint supports:

• Single and composite join keys
• Configurable expected match rates
• Detailed mismatch reporting
• Inner, left, and right join coverage analysis

Implementations

impl JoinCoverageConstraint

pub fn new( left_table: impl Into<String>, right_table: impl Into<String>, ) -> Self

Create a new join coverage constraint.

Arguments

• left_table - Name of the left table in the join
• right_table - Name of the right table in the join

Examples

use term_guard::constraints::JoinCoverageConstraint;

let constraint = JoinCoverageConstraint::new("orders", "customers");

pub fn on( self, left_column: impl Into<String>, right_column: impl Into<String>, ) -> Self

Set the join key columns.

Arguments

• left_column - Column in the left table
• right_column - Column in the right table

pub fn on_multiple( self, keys: Vec<(impl Into<String>, impl Into<String>)>, ) -> Self

Set multiple join key columns for composite joins.

Arguments

• keys - Vector of (left_column, right_column) pairs

pub fn expect_match_rate(self, rate: f64) -> Self

Set the expected match rate.

Arguments

• rate - Expected percentage of rows that should match (0.0 to 1.0)

pub fn coverage_type(self, coverage_type: CoverageType) -> Self

Set the coverage type to check.

pub fn distinct_only(self, distinct: bool) -> Self

Count only distinct values when calculating coverage.

pub fn max_examples_reported(self, max_examples: usize) -> Self

Set the maximum number of unmatched examples to report.

Trait Implementations

impl Clone for JoinCoverageConstraint

fn clone(&self) -> JoinCoverageConstraint

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Constraint for JoinCoverageConstraint

fn evaluate<'life0, 'life1, 'async_trait>( &'life0 self, ctx: &'life1 SessionContext, ) -> Pin<Box<dyn Future<Output = Result<ConstraintResult>> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait,

Evaluates the constraint against the data in the session context.

fn name(&self) -> &str

Returns the name of the constraint.

fn column(&self) -> Option<&str>

Returns the column this constraint operates on (if single-column).

fn description(&self) -> Option<&str>

Returns a description of what this constraint validates.

fn metadata(&self) -> ConstraintMetadata

Returns the metadata associated with this constraint.

impl Debug for JoinCoverageConstraint

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for JoinCoverageConstraint

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for JoinCoverageConstraint

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.