Function extract_pk_equality

nodedb-sql/src/optimizer/point_get.rs:40–75

Extract a simple equality filter on a known PK column.

(filter: &Filter)

/// Extract a simple equality filter on a known PK column.
fn extract_pk_equality(filter: &Filter) -> Option<(String, SqlValue)> {
    match &filter.expr {
        FilterExpr::Comparison {
            field,
            op: CompareOp::Eq,
            value,
        } => {
            // Only optimize for known PK columns.
            let f = field.to_lowercase();
            if f == "id" || f == "document_id" || f == "key" {
                Some((f, value.clone()))
            } else {
                None
            }
        }
        FilterExpr::Expr(SqlExpr::BinaryOp {
            left,
            op: BinaryOp::Eq,
            right,
        }) => {
            let col = match left.as_ref() {
                SqlExpr::Column { name, .. } => name.to_lowercase(),
                _ => return None,
            };
            if col != "id" && col != "document_id" && col != "key" {
                return None;
            }
            let val = match right.as_ref() {
                SqlExpr::Literal(v) => v.clone(),
                _ => return None,
            };
            Some((col, val))
        }
        _ => None,
    }
}