Struct SelectExecutor 

pub struct SelectExecutor { /* private fields */ }

SELECT query executor for SSTable-based storage

Implementations

impl SelectExecutor

pub fn new(schema: Arc<SchemaManager>, storage: Arc<StorageEngine>) -> Self

Create a new SELECT executor

pub async fn execute(&self, plan: OptimizedQueryPlan) -> Result<QueryResult>

Execute an optimized query plan

pub async fn execute_streaming( &self, plan: OptimizedQueryPlan, config: StreamingConfig, ) -> Result<QueryResultIterator>

Execute an optimized query plan with streaming results (Issue #280)

Instead of materializing all rows in memory, this method returns a QueryResultIterator that yields rows incrementally via a bounded channel. This enables memory-efficient processing of large result sets.

Memory Budget

With default StreamingConfig::buffer_size of 1024 rows and ~1KB avg row size:

• Channel buffer: ~1MB in flight
• Background task: minimal overhead
• Total streaming overhead: ~1-2MB (well within 128MB target)

Limitations

Currently supports:

• SSTableScan with predicates (streaming)
• Filter/Limit/Project (applied during scan)

LIMIT (and OFFSET, when present in the plan) is enforced by the streaming producer (execute_streaming_background): it skips OFFSET matches and stops scanning once count rows have been sent, so a LIMIT N query yields exactly N rows without materializing the rest (Issue #581).

For ORDER BY/GROUP BY/DISTINCT, falls back to full execution then streams results.

Trait Implementations

impl Debug for SelectExecutor

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.