feat: introduce experimental_sparse_primary_key_encoding to `Metric…

…EngineConfig`

config/config.md

@@ -170,6 +170,8 @@
 | `region_engine.mito.memtable.data_freeze_threshold` | Integer | `32768` | The max rows of data inside the actively writing buffer in one shard.<br/>Only available for `partition_tree` memtable. |
 | `region_engine.mito.memtable.fork_dictionary_bytes` | String | `1GiB` | Max dictionary bytes.<br/>Only available for `partition_tree` memtable. |
 | `region_engine.file` | -- | -- | Enable the file engine. |
+| `region_engine.metric` | -- | -- | Metric engine options. |
+| `region_engine.metric.experimental_sparse_primary_key_encoding` | Bool | `false` | Whether to enable the experimental sparse primary key encoding. |
 | `logging` | -- | -- | The logging options. |
 | `logging.dir` | String | `/tmp/greptimedb/logs` | The directory to store the log files. If set to empty, logs will not be written to files. |
 | `logging.level` | String | Unset | The log level. Can be `info`/`debug`/`warn`/`error`. |
@@ -506,6 +508,8 @@
 | `region_engine.mito.memtable.data_freeze_threshold` | Integer | `32768` | The max rows of data inside the actively writing buffer in one shard.<br/>Only available for `partition_tree` memtable. |
 | `region_engine.mito.memtable.fork_dictionary_bytes` | String | `1GiB` | Max dictionary bytes.<br/>Only available for `partition_tree` memtable. |
 | `region_engine.file` | -- | -- | Enable the file engine. |
+| `region_engine.metric` | -- | -- | Metric engine options. |
+| `region_engine.metric.experimental_sparse_primary_key_encoding` | Bool | `false` | Whether to enable the experimental sparse primary key encoding. |
 | `logging` | -- | -- | The logging options. |
 | `logging.dir` | String | `/tmp/greptimedb/logs` | The directory to store the log files. If set to empty, logs will not be written to files. |
 | `logging.level` | String | Unset | The log level. Can be `info`/`debug`/`warn`/`error`. |

config/datanode.example.toml

@@ -622,6 +622,12 @@ fork_dictionary_bytes = "1GiB"
 ## Enable the file engine.
 [region_engine.file]
 
+[[region_engine]]
+## Metric engine options.
+[region_engine.metric]
+## Whether to enable the experimental sparse primary key encoding.
+experimental_sparse_primary_key_encoding = false
+
 ## The logging options.
 [logging]
 ## The directory to store the log files. If set to empty, logs will not be written to files.

config/standalone.example.toml

@@ -671,6 +671,12 @@ fork_dictionary_bytes = "1GiB"
 ## Enable the file engine.
 [region_engine.file]
 
+[[region_engine]]
+## Metric engine options.
+[region_engine.metric]
+## Whether to enable the experimental sparse primary key encoding.
+experimental_sparse_primary_key_encoding = false
+
 ## The logging options.
 [logging]
 ## The directory to store the log files. If set to empty, logs will not be written to files.

src/datanode/src/config.rs

@@ -24,6 +24,7 @@ use common_telemetry::logging::{LoggingOptions, TracingOptions};
 use common_wal::config::DatanodeWalConfig;
 use file_engine::config::EngineConfig as FileEngineConfig;
 use meta_client::MetaClientOptions;
+use metric_engine::config::EngineConfig as MetricEngineConfig;
 use mito2::config::MitoConfig;
 use serde::{Deserialize, Serialize};
 use servers::export_metrics::ExportMetricsOption;
@@ -432,6 +433,8 @@ pub enum RegionEngineConfig {
     Mito(MitoConfig),
     #[serde(rename = "file")]
     File(FileEngineConfig),
+    #[serde(rename = "metric")]
+    Metric(MetricEngineConfig),
 }
 
 #[cfg(test)]

src/datanode/src/datanode.rs

@@ -395,6 +395,11 @@ impl DatanodeBuilder {
         plugins: Plugins,
     ) -> Result<Vec<RegionEngineRef>> {
         let mut engines = vec![];
+        let mut metric_engine_config = opts.region_engine.iter().find_map(|c| match c {
+            RegionEngineConfig::Metric(config) => Some(config.clone()),
+            _ => None,
+        });
+
         for engine in &opts.region_engine {
             match engine {
                 RegionEngineConfig::Mito(config) => {
@@ -407,7 +412,10 @@ impl DatanodeBuilder {
                     )
                     .await?;
 
-                    let metric_engine = MetricEngine::new(mito_engine.clone());
+                    let metric_engine = MetricEngine::new(
+                        mito_engine.clone(),
+                        metric_engine_config.take().unwrap_or_default(),
+                    );
                     engines.push(Arc::new(mito_engine) as _);
                     engines.push(Arc::new(metric_engine) as _);
                 }
@@ -418,6 +426,9 @@ impl DatanodeBuilder {
                     );
                     engines.push(Arc::new(engine) as _);
                 }
+                RegionEngineConfig::Metric(_) => {
+                    // Already handled in `build_mito_engine`.
+                }
             }
         }
         Ok(engines)

src/metric-engine/Cargo.toml

@@ -27,6 +27,7 @@ mito2.workspace = true
 mur3 = "0.1"
 object-store.workspace = true
 prometheus.workspace = true
+serde.workspace = true
 serde_json.workspace = true
 snafu.workspace = true
 store-api.workspace = true

src/metric-engine/src/config.rs

@@ -0,0 +1,20 @@
+// Copyright 2023 Greptime Team
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Clone, Default, Serialize, Deserialize, PartialEq, Eq)]
+pub struct EngineConfig {
+    pub experimental_sparse_primary_key_encoding: bool,
+}

src/metric-engine/src/engine.rs

@@ -45,6 +45,7 @@ use store_api::region_request::RegionRequest;
 use store_api::storage::{RegionId, ScanRequest};
 
 use self::state::MetricEngineState;
+use crate::config::EngineConfig;
 use crate::data_region::DataRegion;
 use crate::error::{self, Result, UnsupportedRegionRequestSnafu};
 use crate::metadata_region::MetadataRegion;
@@ -255,7 +256,7 @@ impl RegionEngine for MetricEngine {
 }
 
 impl MetricEngine {
-    pub fn new(mito: MitoEngine) -> Self {
+    pub fn new(mito: MitoEngine, config: EngineConfig) -> Self {
         let metadata_region = MetadataRegion::new(mito.clone());
         let data_region = DataRegion::new(mito.clone());
         Self {
@@ -264,6 +265,7 @@ impl MetricEngine {
                 metadata_region,
                 data_region,
                 state: RwLock::default(),
+                config,
             }),
         }
     }
@@ -304,6 +306,9 @@ struct MetricEngineInner {
     metadata_region: MetadataRegion,
     data_region: DataRegion,
     state: RwLock<MetricEngineState>,
+    /// TODO(weny): remove it after the config is used.
+    #[allow(unused)]
+    config: EngineConfig,
 }
 
 #[cfg(test)]

src/metric-engine/src/engine/create.rs

@@ -549,6 +549,7 @@ mod test {
     use store_api::metric_engine_consts::{METRIC_ENGINE_NAME, PHYSICAL_TABLE_METADATA_KEY};
 
     use super::*;
+    use crate::config::EngineConfig;
     use crate::engine::MetricEngine;
     use crate::test_util::TestEnv;
 
@@ -707,7 +708,7 @@ mod test {
 
         // set up
         let env = TestEnv::new().await;
-        let engine = MetricEngine::new(env.mito());
+        let engine = MetricEngine::new(env.mito(), EngineConfig::default());
         let engine_inner = engine.inner;
 
         // check create data region request

src/metric-engine/src/lib.rs

@@ -52,6 +52,7 @@
 
 #![feature(let_chains)]
 
+pub mod config;
 mod data_region;
 pub mod engine;
 pub mod error;

src/metric-engine/src/test_util.rs

@@ -32,6 +32,7 @@ use store_api::region_request::{
 };
 use store_api::storage::{ColumnId, RegionId};
 
+use crate::config::EngineConfig;
 use crate::data_region::DataRegion;
 use crate::engine::MetricEngine;
 use crate::metadata_region::MetadataRegion;
@@ -54,7 +55,7 @@ impl TestEnv {
     pub async fn with_prefix(prefix: &str) -> Self {
         let mut mito_env = MitoTestEnv::with_prefix(prefix);
         let mito = mito_env.create_engine(MitoConfig::default()).await;
-        let metric = MetricEngine::new(mito.clone());
+        let metric = MetricEngine::new(mito.clone(), EngineConfig::default());
         Self {
             mito_env,
             mito,