feat: initial of write chunks to parquet files

server/src/db.rs

@@ -380,6 +380,28 @@ impl Db {
         Ok(DBChunk::snapshot(&chunk))
     }
 
+    pub fn load_chunk_to_parquet(&self,
+        partition_key: &str,
+        chunk_id: u32,
+    ) -> Result<Arc<DBChunk>> {
+        let chunk = {
+            let partition = self
+                .catalog
+                .valid_partition(partition_key)
+                .context(LoadingChunk {
+                    partition_key,
+                    chunk_id,
+                })?;
+            let partition = partition.read();
+
+            partition.chunk(chunk_id).context(LoadingChunk {
+                partition_key,
+                chunk_id,
+            })?
+        };
+        Ok(&chunk)
+    }
+
     /// Returns the next write sequence number
     pub fn next_sequence(&self) -> u64 {
         self.sequence.fetch_add(1, Ordering::SeqCst)

server/src/db/chunk.rs

@@ -7,7 +7,7 @@ use read_buffer::Database as ReadBufferDb;
 use snafu::{ResultExt, Snafu};
 use tracing::debug;
 
-use std::sync::Arc;
+use std::{path::Path, sync::Arc};
 
 use super::{
     pred::{to_mutable_buffer_predicate, to_read_buffer_predicate},
@@ -68,7 +68,11 @@ pub enum DBChunk {
         partition_key: Arc<String>,
         chunk_id: u32,
     },
-    ParquetFile, // TODO add appropriate type here
+    ParquetFile {
+        path: String, // name of the parquet file
+        partition_key: Arc<String>,
+        chunk_id: u32, // ID of the chunk stored in this parquet file
+    }
 }
 
 impl DBChunk {