2010YOUY01 commented on code in PR #16996:
URL: https://github.com/apache/datafusion/pull/16996#discussion_r2272059908
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datafusion/physical-plan/src/joins/nested_loop_join.rs:
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@@ -660,529 +691,1168 @@ async fn collect_left_input(
))
}
-/// This enumeration represents various states of the nested loop join
algorithm.
-#[derive(Debug, Clone)]
-enum NestedLoopJoinStreamState {
- /// The initial state, indicating that build-side data not collected yet
- WaitBuildSide,
- /// Indicates that build-side has been collected, and stream is ready for
- /// fetching probe-side
- FetchProbeBatch,
- /// Indicates that a non-empty batch has been fetched from probe-side, and
- /// is ready to be processed
- ProcessProbeBatch(RecordBatch),
- /// Preparation phase: Gathers the indices of unmatched rows from the
build-side.
- /// This state is entered for join types that emit unmatched build-side
rows
- /// (e.g., LEFT and FULL joins) after the entire probe-side input has been
consumed.
- PrepareUnmatchedBuildRows,
- /// Output unmatched build-side rows.
- /// The indices for rows to output has already been calculated in the
previous
- /// `PrepareUnmatchedBuildRows` state. In this state the final batch will
be materialized incrementally.
- // The inner `RecordBatch` is an empty dummy batch used to get right
schema.
- OutputUnmatchedBuildRows(RecordBatch),
- /// Indicates that NestedLoopJoinStream execution is completed
- Completed,
-}
-
-impl NestedLoopJoinStreamState {
- /// Tries to extract a `ProcessProbeBatchState` from the
- /// `NestedLoopJoinStreamState` enum. Returns an error if state is not
- /// `ProcessProbeBatchState`.
- fn try_as_process_probe_batch(&mut self) -> Result<&RecordBatch> {
- match self {
- NestedLoopJoinStreamState::ProcessProbeBatch(state) => Ok(state),
- _ => internal_err!("Expected join stream in ProcessProbeBatch
state"),
- }
- }
-}
-
-/// Tracks incremental output of join result batches.
-///
-/// Initialized with all matching pairs that satisfy the join predicate.
-/// Pairs are stored as indices in `build_indices` and `probe_indices`
-/// Each poll outputs a batch within the configured size limit and updates
-/// processed_count until all pairs are consumed.
-///
-/// Example: 5000 matches, batch size limit is 100
-/// - Poll 1: output batch[0..100], processed_count = 100
-/// - Poll 2: output batch[100..200], processed_count = 200
-/// - ...continues until processed_count = 5000
-struct JoinResultProgress {
- /// Row indices from build-side table (left table).
- build_indices: PrimitiveArray<UInt64Type>,
- /// Row indices from probe-side table (right table).
- probe_indices: PrimitiveArray<UInt32Type>,
- /// Number of index pairs already processed into output batches.
- /// We have completed join result for indices [0..processed_count).
- processed_count: usize,
+/// States for join processing. See `poll_next()` comment for more details
about
+/// state transitions.
+#[derive(Debug, Clone, Copy)]
+enum NLJState {
+ BufferingLeft,
+ FetchingRight,
+ ProbeRight,
+ EmitRightUnmatched,
+ EmitLeftUnmatched,
+ Done,
}
-
-/// A stream that issues [RecordBatch]es as they arrive from the right of the
join.
-struct NestedLoopJoinStream {
- /// Input schema
- schema: Arc<Schema>,
+pub(crate) struct NestedLoopJoinStream {
+ // ========================================================================
+ // PROPERTIES:
+ // Operator's properties that remain constant
+ //
+ // Note: The implementation uses the terms left/inner/build-side table and
Review Comment:
Updated in
[8cc3654](https://github.com/apache/datafusion/pull/16996/commits/8cc365491cdeab7dec8aac5d3da458191b2f3e16).
Thanks!
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