Method transform

src/transform/src/lib.rs:219–243

Transforms a relation into a functionally equivalent relation. This is a wrapper around `actually_perform_transform` that also measures the time taken and updates the optimizer metrics.

(
        &self,
        relation: &mut MirRelationExpr,
        args: &mut TransformCtx,
    )

    /// This is a wrapper around `actually_perform_transform` that also
    /// measures the time taken and updates the optimizer metrics.
    fn transform(
        &self,
        relation: &mut MirRelationExpr,
        args: &mut TransformCtx,
    ) -> Result<(), TransformError> {
        let hash_before = args
            .global_id
            .and_then(|id| args.last_hash.get(&id).copied())
            .unwrap_or_else(|| relation.hash_to_u64());

        mz_ore::soft_assert_eq_no_log!(hash_before, relation.hash_to_u64(), "cached hash clash");
        // actually run the transform, recording the time taken
        let start = std::time::Instant::now();
        let res = self.actually_perform_transform(relation, args);
        let duration = start.elapsed();

        let hash_after = args.update_last_hash(relation);
        if let Some(metrics) = &mut args.metrics {
            let transform_name = self.name();
            metrics.observe_transform_time(transform_name, duration);
            metrics.inc_transform(hash_before != hash_after, transform_name);
        }

        res
    }

    /// Transform a relation into a functionally equivalent relation.
    ///