risingwave_frontend::optimizer::plan_node::convert

Trait ToStream

Source 
pub trait ToStream {
    // Required methods
    fn logical_rewrite_for_stream(
        &self,
        ctx: &mut RewriteStreamContext,
    ) -> Result<(LogicalPlanRef, ColIndexMapping)>;
    fn to_stream(&self, ctx: &mut ToStreamContext) -> Result<StreamPlanRef>;

    // Provided method
    fn to_stream_with_dist_required(
        &self,
        required_dist: &RequiredDist,
        ctx: &mut ToStreamContext,
    ) -> Result<StreamPlanRef> { ... }
}
Expand description

ToStream converts a logical plan node to streaming physical node with an optional required distribution.

when implement this trait you can choose the two ways

  • Implement to_stream and use the default implementation of to_stream_with_dist_required
  • Or, if the required distribution is given, there will be a better plan. For example a hash join with hash-key(a,b) and the plan is required hash-distributed by (a,b,c). you can implement to_stream_with_dist_required, and implement to_stream with to_stream_with_dist_required(RequiredDist::Any). you can see LogicalProject as an example.

Required Methods§

Source

fn logical_rewrite_for_stream( &self, ctx: &mut RewriteStreamContext, ) -> Result<(LogicalPlanRef, ColIndexMapping)>

logical_rewrite_for_stream will rewrite the logical node, and return (new_plan_node, col_mapping), the col_mapping is for original columns have been changed into some other position.

Now it is used to:

  1. ensure every plan node’s output having pk column
  2. add row_count() in every Agg
Source

fn to_stream(&self, ctx: &mut ToStreamContext) -> Result<StreamPlanRef>

to_stream is equivalent to to_stream_with_dist_required(RequiredDist::Any)

Provided Methods§

Source

fn to_stream_with_dist_required( &self, required_dist: &RequiredDist, ctx: &mut ToStreamContext, ) -> Result<StreamPlanRef>

convert the plan to streaming physical plan and satisfy the required distribution

Implementors§