Function can_skip_string

nodedb-columnar/src/predicate.rs:322–356

Block-skip logic for string predicates.

(op: PredicateOp, value: &str, stats: &BlockStats)

/// Block-skip logic for string predicates.
fn can_skip_string(op: PredicateOp, value: &str, stats: &BlockStats) -> bool {
    let (Some(smin), Some(smax)) = (&stats.str_min, &stats.str_max) else {
        // No string zone-map information → cannot skip.
        return false;
    };

    let skip_by_range = match op {
        // column > value → skip if block.max <= value (no string is > value)
        PredicateOp::Gt => smax.as_str() <= value,
        // column >= value → skip if block.max < value
        PredicateOp::Gte => smax.as_str() < value,
        // column < value → skip if block.min >= value
        PredicateOp::Lt => smin.as_str() >= value,
        // column <= value → skip if block.min > value
        PredicateOp::Lte => smin.as_str() > value,
        // column = value → skip if value outside [min, max]
        PredicateOp::Eq => value < smin.as_str() || value > smax.as_str(),
        // column != value → skip only if the entire block contains that exact value
        PredicateOp::Ne => smin.as_str() == value && smax.as_str() == value,
    };

    if skip_by_range {
        return true;
    }

    // For Eq predicates, apply bloom filter as an additional fast-reject.
    if op == PredicateOp::Eq
        && let Some(ref bloom) = stats.bloom
        && !bloom_may_contain(bloom, value)
    {
        return true; // Bloom says "definitely not present" → skip.
    }

    false
}

// ── Bloom filter ────────────────────────────────────────────────────────────