feat: Implement write and fork for the new memtable

src/mito2/src/memtable/merge_tree.rs

@@ -262,3 +262,85 @@ impl MemtableBuilder for MergeTreeMemtableBuilder {
         ))
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use common_time::Timestamp;
+
+    use super::*;
+    use crate::test_util::memtable_util;
+
+    #[test]
+    fn test_memtable_sorted_input() {
+        write_sorted_input(true);
+        write_sorted_input(false);
+    }
+
+    fn write_sorted_input(has_pk: bool) {
+        let metadata = if has_pk {
+            memtable_util::metadata_with_primary_key(vec![1, 0], true)
+        } else {
+            memtable_util::metadata_with_primary_key(vec![], false)
+        };
+        let timestamps = (0..100).collect::<Vec<_>>();
+        let kvs =
+            memtable_util::build_key_values(&metadata, "hello".to_string(), 42, &timestamps, 1);
+        let memtable = MergeTreeMemtable::new(1, metadata, None, &MergeTreeConfig::default());
+        memtable.write(&kvs).unwrap();
+
+        // TODO(yingwen): Test iter.
+
+        let stats = memtable.stats();
+        assert!(stats.bytes_allocated() > 0);
+        assert_eq!(
+            Some((
+                Timestamp::new_millisecond(0),
+                Timestamp::new_millisecond(99)
+            )),
+            stats.time_range()
+        );
+    }
+
+    #[test]
+    fn test_memtable_unsorted_input() {
+        write_iter_unsorted_input(true);
+        write_iter_unsorted_input(false);
+    }
+
+    fn write_iter_unsorted_input(has_pk: bool) {
+        let metadata = if has_pk {
+            memtable_util::metadata_with_primary_key(vec![1, 0], true)
+        } else {
+            memtable_util::metadata_with_primary_key(vec![], false)
+        };
+        let memtable =
+            MergeTreeMemtable::new(1, metadata.clone(), None, &MergeTreeConfig::default());
+
+        let kvs = memtable_util::build_key_values(
+            &metadata,
+            "hello".to_string(),
+            0,
+            &[1, 3, 7, 5, 6],
+            0, // sequence 0, 1, 2, 3, 4
+        );
+        memtable.write(&kvs).unwrap();
+
+        let kvs = memtable_util::build_key_values(
+            &metadata,
+            "hello".to_string(),
+            0,
+            &[5, 2, 4, 0, 7],
+            5, // sequence 5, 6, 7, 8, 9
+        );
+        memtable.write(&kvs).unwrap();
+
+        // TODO(yingwen): Test iter.
+
+        let stats = memtable.stats();
+        assert!(stats.bytes_allocated() > 0);
+        assert_eq!(
+            Some((Timestamp::new_millisecond(0), Timestamp::new_millisecond(7))),
+            stats.time_range()
+        );
+    }
+}

src/mito2/src/memtable/merge_tree/data.rs

@@ -43,10 +43,13 @@ use crate::error;
 use crate::error::Result;
 use crate::memtable::key_values::KeyValue;
 use crate::memtable::merge_tree::merger::{DataNode, DataSource, Merger};
-use crate::memtable::merge_tree::{PkId, PkIndex};
+use crate::memtable::merge_tree::PkIndex;
 
 const PK_INDEX_COLUMN_NAME: &str = "__pk_index";
 
+/// Initial capacity for the data buffer.
+pub(crate) const DATA_INIT_CAP: usize = 8;
+
 /// Data part batches returns by `DataParts::read`.
 #[derive(Debug, Clone)]
 pub struct DataBatch {
@@ -128,9 +131,9 @@ impl DataBuffer {
     }
 
     /// Writes a row to data buffer.
-    pub fn write_row(&mut self, pk_id: PkId, kv: KeyValue) {
+    pub fn write_row(&mut self, pk_index: PkIndex, kv: KeyValue) {
         self.ts_builder.push_value_ref(kv.timestamp());
-        self.pk_index_builder.push(Some(pk_id.pk_index));
+        self.pk_index_builder.push(Some(pk_index));
         self.sequence_builder.push(Some(kv.sequence()));
         self.op_type_builder.push(Some(kv.op_type() as u8));
 
@@ -662,9 +665,9 @@ pub struct ParquetPart {
 /// Data parts under a shard.
 pub struct DataParts {
     /// The active writing buffer.
-    pub(crate) active: DataBuffer,
+    active: DataBuffer,
     /// immutable (encoded) parts.
-    pub(crate) frozen: Vec<DataPart>,
+    frozen: Vec<DataPart>,
 }
 
 impl DataParts {
@@ -675,9 +678,14 @@ impl DataParts {
         }
     }
 
-    /// Writes one row into active part.
-    pub fn write_row(&mut self, pk_id: PkId, kv: KeyValue) {
-        self.active.write_row(pk_id, kv)
+    pub(crate) fn with_frozen(mut self, frozen: Vec<DataPart>) -> Self {
+        self.frozen = frozen;
+        self
+    }
+
+    /// Writes a row into parts.
+    pub fn write_row(&mut self, pk_index: PkIndex, kv: KeyValue) {
+        self.active.write_row(pk_index, kv)
     }
 
     /// Freezes the active data buffer into frozen data parts.
@@ -932,13 +940,7 @@ mod tests {
         );
 
         for kv in kvs.iter() {
-            buffer.write_row(
-                PkId {
-                    shard_id: 0,
-                    pk_index,
-                },
-                kv,
-            );
+            buffer.write_row(pk_index, kv);
         }
     }
 

src/mito2/src/memtable/merge_tree/dict.rs

@@ -61,19 +61,21 @@ impl KeyDictBuilder {
         self.pk_to_index.get(key).copied()
     }
 
+    /// Returns true if the builder is full.
+    pub fn is_full(&self) -> bool {
+        self.num_keys >= self.capacity
+    }
+
     /// Adds the key to the builder and returns its index if the builder is not full.
     ///
-    /// Returns `None` if the builder is full.
-    pub fn try_insert_key(&mut self, key: &[u8], metrics: &mut WriteMetrics) -> Option<PkIndex> {
+    /// # Panics
+    /// Panics if the builder is full.
+    pub fn insert_key(&mut self, key: &[u8], metrics: &mut WriteMetrics) -> PkIndex {
+        assert!(!self.is_full());
+
         if let Some(pk_index) = self.pk_to_index.get(key).copied() {
             // Already in the builder.
-            return Some(pk_index);
-        }
-
-        // A new key.
-        if self.num_keys >= self.capacity {
-            // The builder is full.
-            return None;
+            return pk_index;
         }
 
         if self.key_buffer.len() >= MAX_KEYS_PER_BLOCK.into() {
@@ -91,7 +93,7 @@ impl KeyDictBuilder {
         metrics.key_bytes += key.len() * 2;
         self.key_bytes_in_index += key.len();
 
-        Some(pk_index)
+        pk_index
     }
 
     /// Memory size of the builder.
@@ -129,11 +131,12 @@ impl KeyDictBuilder {
             pk_to_index,
             dict_blocks: std::mem::take(&mut self.dict_blocks),
             key_positions,
+            key_bytes_in_index: self.key_bytes_in_index,
         })
     }
 
-    /// Scans the builder.
-    pub fn scan(&self) -> DictBuilderReader {
+    /// Reads the builder.
+    pub fn read(&self) -> DictBuilderReader {
         let sorted_pk_indices = self.pk_to_index.values().copied().collect();
         let block = self.key_buffer.finish_cloned();
         let mut blocks = Vec::with_capacity(self.dict_blocks.len() + 1);
@@ -162,38 +165,46 @@ impl DictBuilderReader {
         }
     }
 
-    /// Returns true if the item in the reader is valid.
-    pub fn is_valid(&self) -> bool {
-        self.offset < self.sorted_pk_indices.len()
+    /// Returns the number of keys.
+    pub fn num_keys(&self) -> usize {
+        self.sorted_pk_indices.len()
+    }
+
+    /// Gets the i-th pk index.
+    pub fn pk_index(&self, offset: usize) -> PkIndex {
+        self.sorted_pk_indices[offset]
     }
 
-    /// Returns current key.
-    pub fn current_key(&self) -> &[u8] {
-        let pk_index = self.current_pk_index();
+    /// Gets the i-th key.
+    pub fn key(&self, offset: usize) -> &[u8] {
+        let pk_index = self.pk_index(offset);
         self.key_by_pk_index(pk_index)
     }
 
-    /// Returns current [PkIndex] of the key.
-    pub fn current_pk_index(&self) -> PkIndex {
-        assert!(self.is_valid());
-        self.sorted_pk_indices[self.offset]
+    /// Gets the key by the pk index.
+    pub fn key_by_pk_index(&self, pk_index: PkIndex) -> &[u8] {
+        let block_idx = pk_index / MAX_KEYS_PER_BLOCK;
+        self.blocks[block_idx as usize].key_by_pk_index(pk_index)
     }
 
-    /// Advances the reader.
-    pub fn next(&mut self) {
-        assert!(self.is_valid());
-        self.offset += 1;
+    /// Returns pk weights to sort a data part and replaces pk indices.
+    pub(crate) fn pk_weights_to_sort_data(&self) -> Vec<u16> {
+        compute_pk_weights(&self.sorted_pk_indices)
     }
 
     /// Returns pk indices sorted by keys.
     pub(crate) fn sorted_pk_index(&self) -> &[PkIndex] {
         &self.sorted_pk_indices
     }
+}
 
-    fn key_by_pk_index(&self, pk_index: PkIndex) -> &[u8] {
-        let block_idx = pk_index / MAX_KEYS_PER_BLOCK;
-        self.blocks[block_idx as usize].key_by_pk_index(pk_index)
+/// Returns pk weights to sort a data part and replaces pk indices.
+fn compute_pk_weights(sorted_pk_indices: &[PkIndex]) -> Vec<u16> {
+    let mut pk_weights = vec![0; sorted_pk_indices.len()];
+    for (weight, pk_index) in sorted_pk_indices.iter().enumerate() {
+        pk_weights[*pk_index as usize] = weight as u16;
     }
+    pk_weights
 }
 
 /// A key dictionary.
@@ -206,6 +217,7 @@ pub struct KeyDict {
     dict_blocks: Vec<DictBlock>,
     /// Maps pk index to position of the key in [Self::dict_blocks].
     key_positions: Vec<PkIndex>,
+    key_bytes_in_index: usize,
 }
 
 pub type KeyDictRef = Arc<KeyDict>;
@@ -220,6 +232,21 @@ impl KeyDict {
         let block_index = position / MAX_KEYS_PER_BLOCK;
         self.dict_blocks[block_index as usize].key_by_pk_index(position)
     }
+
+    /// Gets the pk index by the key.
+    pub fn get_pk_index(&self, key: &[u8]) -> Option<PkIndex> {
+        self.pk_to_index.get(key).copied()
+    }
+
+    /// Returns pk weights to sort a data part and replaces pk indices.
+    pub(crate) fn pk_weights_to_sort_data(&self) -> Vec<u16> {
+        compute_pk_weights(&self.key_positions)
+    }
+
+    /// Returns the shared memory size.
+    pub(crate) fn shared_memory_size(&self) -> usize {
+        self.key_bytes_in_index
+    }
 }
 
 /// Buffer to store unsorted primary keys.
@@ -364,7 +391,8 @@ mod tests {
         let mut last_pk_index = None;
         let mut metrics = WriteMetrics::default();
         for key in &keys {
-            let pk_index = builder.try_insert_key(key, &mut metrics).unwrap();
+            assert!(!builder.is_full());
+            let pk_index = builder.insert_key(key, &mut metrics);
             last_pk_index = Some(pk_index);
         }
         assert_eq!(num_keys - 1, last_pk_index.unwrap());
@@ -379,10 +407,9 @@ mod tests {
         expect.sort_unstable_by(|a, b| a.0.cmp(&b.0));
 
         let mut result = Vec::with_capacity(expect.len());
-        let mut reader = builder.scan();
-        while reader.is_valid() {
-            result.push((reader.current_key().to_vec(), reader.current_pk_index()));
-            reader.next();
+        let reader = builder.read();
+        for i in 0..reader.num_keys() {
+            result.push((reader.key(i).to_vec(), reader.pk_index(i)));
         }
         assert_eq!(expect, result);
     }
@@ -397,9 +424,7 @@ mod tests {
         for i in 0..num_keys {
             // Each key is 5 bytes.
             let key = format!("{i:05}");
-            builder
-                .try_insert_key(key.as_bytes(), &mut metrics)
-                .unwrap();
+            builder.insert_key(key.as_bytes(), &mut metrics);
         }
         // num_keys * 5 * 2
         assert_eq!(5130, metrics.key_bytes);

src/mito2/src/memtable/merge_tree/merger.rs

@@ -407,7 +407,6 @@ mod tests {
 
     use super::*;
     use crate::memtable::merge_tree::data::DataBuffer;
-    use crate::memtable::merge_tree::PkId;
     use crate::test_util::memtable_util::{build_key_values_with_ts_seq_values, metadata_for_test};
 
     fn write_rows_to_buffer(
@@ -429,13 +428,7 @@ mod tests {
         );
 
         for kv in kvs.iter() {
-            buffer.write_row(
-                PkId {
-                    shard_id: 0,
-                    pk_index,
-                },
-                kv,
-            );
+            buffer.write_row(pk_index, kv);
         }
 
         *sequence += rows;