[Improvement](pipeline) Terminate early for short-circuit join (#23378)

apache · Aug 23, 2023 · b918840 · b918840
1 parent c827aa9
commit b918840
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Showing 5 changed files with 48 additions and 6 deletions.
diff --git a/be/src/exec/exec_node.h b/be/src/exec/exec_node.h
@@ -134,6 +134,8 @@ class ExecNode {
 
     bool can_read() const { return _can_read; }
 
+    [[nodiscard]] virtual bool can_terminate_early() { return false; }
+
     // Sink Data to ExecNode to do some stock work, both need impl with method: get_result
     // `eos` means source is exhausted, exec node should do some finalize work
     // Eg: Aggregation, Sort

diff --git a/be/src/pipeline/exec/operator.h b/be/src/pipeline/exec/operator.h
@@ -199,6 +199,8 @@ class OperatorBase {
 
     virtual bool can_write() { return false; } // for sink
 
+    [[nodiscard]] virtual bool can_terminate_early() { return false; }
+
     /**
      * The main method to execute a pipeline task.
      * Now it is a pull-based pipeline and operators pull data from its child by this method.
@@ -321,6 +323,8 @@ class StreamingOperator : public OperatorBase {
 
     ~StreamingOperator() override = default;
 
+    [[nodiscard]] bool can_terminate_early() override { return _node->can_terminate_early(); }
+
     Status prepare(RuntimeState* state) override {
         _node->increase_ref();
         _use_projection = _node->has_output_row_descriptor();

diff --git a/be/src/pipeline/pipeline_task.cpp b/be/src/pipeline/pipeline_task.cpp
@@ -222,23 +222,23 @@ Status PipelineTask::execute(bool* eos) {
             set_state(PipelineTaskState::BLOCKED_FOR_DEPENDENCY);
             return Status::OK();
         }
-        if (!_source->can_read()) {
+        if (!source_can_read()) {
             set_state(PipelineTaskState::BLOCKED_FOR_SOURCE);
             return Status::OK();
         }
-        if (!_sink->can_write()) {
+        if (!sink_can_write()) {
             set_state(PipelineTaskState::BLOCKED_FOR_SINK);
             return Status::OK();
         }
     }
 
     this->set_begin_execute_time();
     while (!_fragment_context->is_canceled()) {
-        if (_data_state != SourceState::MORE_DATA && !_source->can_read()) {
+        if (_data_state != SourceState::MORE_DATA && !source_can_read()) {
             set_state(PipelineTaskState::BLOCKED_FOR_SOURCE);
             break;
         }
-        if (!_sink->can_write()) {
+        if (!sink_can_write()) {
             set_state(PipelineTaskState::BLOCKED_FOR_SINK);
             break;
         }

diff --git a/be/src/pipeline/pipeline_task.h b/be/src/pipeline/pipeline_task.h
@@ -152,13 +152,47 @@ class PipelineTask {
         return false;
     }
 
-    bool source_can_read() { return _source->can_read(); }
+    bool source_can_read() { return _source->can_read() || ignore_blocking_source();; }
 
     bool runtime_filters_are_ready_or_timeout() {
         return _source->runtime_filters_are_ready_or_timeout();
     }
 
-    bool sink_can_write() { return _sink->can_write(); }
+    bool sink_can_write() { return _sink->can_write() || ignore_blocking_sink(); }
+    /**
+     * Consider the query plan below:
+     *
+     *      ExchangeSource     JoinBuild1
+     *            \              /
+     *         JoinProbe1 (Right Outer)    JoinBuild2
+     *                   \                   /
+     *                 JoinProbe2 (Right Outer)
+     *                          |
+     *                        Sink
+     *
+     * Assume JoinBuild1/JoinBuild2 outputs 0 rows, this pipeline task should not be blocked by ExchangeSource
+     * because we have a determined conclusion that JoinProbe1/JoinProbe2 will also output 0 rows.
+     *
+     * Assume JoinBuild2 outputs > 0 rows, this pipeline task may be blocked by Sink because JoinProbe2 will
+     * produce more data.
+     *
+     * Assume both JoinBuild2 outputs 0 rows this pipeline task should not be blocked by ExchangeSource
+     * and Sink because JoinProbe2 will always produce 0 rows and terminate early.
+     *
+     * In a nutshell, we should follow the rules:
+     * 1. if any operator in pipeline can terminate early, this task should never be blocked by source operator.
+     * 2. if the last operator (except sink) can terminate early, this task should never be blocked by sink operator.
+     */
+    [[nodiscard]] virtual bool ignore_blocking_sink() { return _root->can_terminate_early(); }
+
+    [[nodiscard]] virtual bool ignore_blocking_source() {
+        for (size_t i = 1; i < _operators.size(); i++) {
+            if (_operators[i]->can_terminate_early()) {
+                return true;
+            }
+        }
+        return false;
+    }
 
     Status finalize();
 

diff --git a/be/src/vec/exec/join/vjoin_node_base.h b/be/src/vec/exec/join/vjoin_node_base.h
@@ -74,6 +74,8 @@ class VJoinNodeBase : public ExecNode {
 
     virtual Status init(const TPlanNode& tnode, RuntimeState* state = nullptr) override;
 
+    [[nodiscard]] bool can_terminate_early() override { return _short_circuit_for_probe; }
+
 protected:
     // Construct the intermediate blocks to store the results from join operation.
     void _construct_mutable_join_block();