support batch_parallelism

e2e_test/batch/basic/join.slt.part

@@ -32,6 +32,25 @@ select * from t1 join t2 using(v1) join t3 using(v2);
 ----
 2 1 3 3
 
+statement ok
+set batch_parallelism = 1;
+
+query IIIIII
+select * from t1 join t2 using(v1) join t3 using(v2);
+----
+2 1 3 3
+
+statement ok
+set batch_parallelism = 1000;
+
+query IIIIII
+select * from t1 join t2 using(v1) join t3 using(v2);
+----
+2 1 3 3
+
+statement ok
+set batch_parallelism = 0;
+
 statement ok
 create index i1 on t1(v1) include(v2);
 

src/common/src/session_config/mod.rs

@@ -17,6 +17,7 @@ mod search_path;
 mod transaction_isolation_level;
 mod visibility_mode;
 
+use std::num::NonZeroU64;
 use std::ops::Deref;
 
 use chrono_tz::Tz;
@@ -32,7 +33,7 @@ use crate::util::epoch::Epoch;
 
 // This is a hack, &'static str is not allowed as a const generics argument.
 // TODO: refine this using the adt_const_params feature.
-const CONFIG_KEYS: [&str; 20] = [
+const CONFIG_KEYS: [&str; 21] = [
     "RW_IMPLICIT_FLUSH",
     "CREATE_COMPACTION_GROUP_FOR_MV",
     "QUERY_MODE",
@@ -53,6 +54,7 @@ const CONFIG_KEYS: [&str; 20] = [
     "RW_FORCE_TWO_PHASE_AGG",
     "RW_ENABLE_SHARE_PLAN",
     "INTERVALSTYLE",
+    "BATCH_PARALLELISM",
 ];
 
 // MUST HAVE 1v1 relationship to CONFIG_KEYS. e.g. CONFIG_KEYS[IMPLICIT_FLUSH] =
@@ -77,6 +79,7 @@ const ENABLE_TWO_PHASE_AGG: usize = 16;
 const FORCE_TWO_PHASE_AGG: usize = 17;
 const RW_ENABLE_SHARE_PLAN: usize = 18;
 const INTERVAL_STYLE: usize = 19;
+const BATCH_PARALLELISM: usize = 20;
 
 trait ConfigEntry: Default + for<'a> TryFrom<&'a [&'a str], Error = RwError> {
     fn entry_name() -> &'static str;
@@ -277,6 +280,7 @@ type EnableTwoPhaseAgg = ConfigBool<ENABLE_TWO_PHASE_AGG, true>;
 type ForceTwoPhaseAgg = ConfigBool<FORCE_TWO_PHASE_AGG, false>;
 type EnableSharePlan = ConfigBool<RW_ENABLE_SHARE_PLAN, true>;
 type IntervalStyle = ConfigString<INTERVAL_STYLE>;
+type BatchParallelism = ConfigU64<BATCH_PARALLELISM, 0>;
 
 #[derive(Derivative)]
 #[derivative(Default)]
@@ -353,6 +357,8 @@ pub struct ConfigMap {
 
     /// see <https://www.postgresql.org/docs/current/runtime-config-client.html#GUC-INTERVALSTYLE>
     interval_style: IntervalStyle,
+
+    batch_parallelism: BatchParallelism,
 }
 
 impl ConfigMap {
@@ -408,6 +414,8 @@ impl ConfigMap {
             self.enable_share_plan = val.as_slice().try_into()?;
         } else if key.eq_ignore_ascii_case(IntervalStyle::entry_name()) {
             self.interval_style = val.as_slice().try_into()?;
+        } else if key.eq_ignore_ascii_case(BatchParallelism::entry_name()) {
+            self.batch_parallelism = val.as_slice().try_into()?;
         } else {
             return Err(ErrorCode::UnrecognizedConfigurationParameter(key.to_string()).into());
         }
@@ -456,6 +464,8 @@ impl ConfigMap {
             Ok(self.enable_share_plan.to_string())
         } else if key.eq_ignore_ascii_case(IntervalStyle::entry_name()) {
             Ok(self.interval_style.to_string())
+        } else if key.eq_ignore_ascii_case(BatchParallelism::entry_name()) {
+            Ok(self.batch_parallelism.to_string())
         } else {
             Err(ErrorCode::UnrecognizedConfigurationParameter(key.to_string()).into())
         }
@@ -558,6 +568,11 @@ impl ConfigMap {
                 setting : self.interval_style.to_string(),
                 description : String::from("It is typically set by an application upon connection to the server.")
             },
+            VariableInfo{
+                name : BatchParallelism::entry_name().to_lowercase(),
+                setting : self.batch_parallelism.to_string(),
+                description: String::from("Sets the parallelism for batch. If 0, use default value.")
+            },
         ]
     }
 
@@ -646,4 +661,11 @@ impl ConfigMap {
     pub fn get_interval_style(&self) -> &str {
         &self.interval_style
     }
+
+    pub fn get_batch_parallelism(&self) -> Option<NonZeroU64> {
+        if self.batch_parallelism.0 != 0 {
+            return Some(NonZeroU64::new(self.batch_parallelism.0).unwrap());
+        }
+        None
+    }
 }

src/frontend/src/handler/explain.rs

@@ -145,6 +145,7 @@ pub async fn handle_explain(
                     plan_fragmenter = Some(BatchPlanFragmenter::new(
                         session.env().worker_node_manager_ref(),
                         session.env().catalog_reader().clone(),
+                        session.config().get_batch_parallelism(),
                         plan,
                     )?);
                 }

src/frontend/src/handler/query.rs

@@ -162,6 +162,7 @@ pub async fn handle_query(
         let plan_fragmenter = BatchPlanFragmenter::new(
             session.env().worker_node_manager_ref(),
             session.env().catalog_reader().clone(),
+            session.config().get_batch_parallelism(),
             plan,
         )?;
         context.append_notice(&mut notice);

src/frontend/src/scheduler/distributed/query.rs

@@ -660,6 +660,7 @@ pub(crate) mod tests {
         let fragmenter = BatchPlanFragmenter::new(
             worker_node_manager,
             catalog_reader,
+            None,
             batch_exchange_node.clone(),
         )
         .unwrap();

src/frontend/src/scheduler/plan_fragmenter.rs

@@ -12,8 +12,10 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+use std::cmp::min;
 use std::collections::{HashMap, HashSet};
 use std::fmt::{Debug, Formatter};
+use std::num::NonZeroU64;
 use std::sync::Arc;
 
 use anyhow::anyhow;
@@ -120,6 +122,12 @@ pub struct BatchPlanFragmenter {
     worker_node_manager: WorkerNodeManagerRef,
     catalog_reader: CatalogReader,
 
+    /// if batch_parallelism is None, it means no limit, we will use the available nodes count as
+    /// parallelism.
+    /// if batch_parallelism is Some(num), we will use the min(num, the available
+    /// nodes count) as parallelism.
+    batch_parallelism: Option<NonZeroU64>,
+
     stage_graph_builder: Option<StageGraphBuilder>,
     stage_graph: Option<StageGraph>,
 }
@@ -136,6 +144,7 @@ impl BatchPlanFragmenter {
     pub fn new(
         worker_node_manager: WorkerNodeManagerRef,
         catalog_reader: CatalogReader,
+        batch_parallelism: Option<NonZeroU64>,
         batch_node: PlanRef,
     ) -> SchedulerResult<Self> {
         let mut plan_fragmenter = Self {
@@ -144,6 +153,7 @@ impl BatchPlanFragmenter {
             next_stage_id: 0,
             worker_node_manager,
             catalog_reader,
+            batch_parallelism,
             stage_graph: None,
         };
         plan_fragmenter.split_into_stage(batch_node)?;
@@ -751,6 +761,11 @@ impl BatchPlanFragmenter {
                     lookup_join_parallelism
                 } else if source_info.is_some() {
                     0
+                } else if let Some(num) = self.batch_parallelism {
+                    min(
+                        num.get() as usize,
+                        self.worker_node_manager.worker_node_count(),
+                    )
                 } else {
                     self.worker_node_manager.worker_node_count()
                 }