Function analyse_lateral_where

nodedb-sql/src/planner/lateral/correlation.rs:40–57

Analyse the WHERE clause of a LATERAL subquery. `outer_alias` is the alias or name of the driving table (e.g. `"u"` for `FROM users u`). Any compound identifier `outer_alias.col` or `col = outer_alias.col` is treated as a correlation reference to the outer side.

(subquery: &ast::Query, outer_alias: &str)

/// `FROM users u`). Any compound identifier `outer_alias.col` or `col = outer_alias.col`
/// is treated as a correlation reference to the outer side.
pub fn analyse_lateral_where(subquery: &ast::Query, outer_alias: &str) -> CorrelationAnalysis {
    let select = match subquery.body.as_ref() {
        SetExpr::Select(s) => s,
        _ => return CorrelationAnalysis::default(),
    };
    let Some(where_expr) = &select.selection else {
        return CorrelationAnalysis::default();
    };

    let mut analysis = CorrelationAnalysis::default();
    analysis.remaining = extract_correlation_recursive(
        where_expr,
        outer_alias,
        &mut analysis.equi_keys,
        &mut analysis.non_equi,
    );
    analysis
}

/// Walk the WHERE expression, extracting correlated predicates.
///