fix empty index error

meilisearch-http/src/index/dump.rs

@@ -1,15 +1,15 @@
-use std::{fs::{create_dir_all, File}, path::Path, sync::Arc};
+use std::{fs::{create_dir_all, File}, io::{BufRead, BufReader}, path::Path, sync::Arc};
 
+use anyhow::bail;
 use anyhow::Context;
 use heed::RoTxn;
 use indexmap::IndexMap;
 use milli::update::{IndexDocumentsMethod, UpdateFormat::JsonStream};
 use serde::{Deserialize, Serialize};
-use anyhow::bail;
 
 use crate::option::IndexerOpts;
 
-use super::{Unchecked, Index, Settings, update_handler::UpdateHandler};
+use super::{update_handler::UpdateHandler, Index, Settings, Unchecked};
 
 #[derive(Serialize, Deserialize)]
 struct DumpMeta {
@@ -64,7 +64,10 @@ impl Index {
 
         let settings = self.settings_txn(txn)?.into_unchecked();
         let primary_key = self.primary_key(txn)?.map(String::from);
-        let meta = DumpMeta { settings, primary_key };
+        let meta = DumpMeta {
+            settings,
+            primary_key,
+        };
 
         serde_json::to_writer(&mut meta_file, &meta)?;
 
@@ -86,7 +89,10 @@ impl Index {
 
         let meta_path = src.as_ref().join(META_FILE_NAME);
         let mut meta_file = File::open(meta_path)?;
-        let DumpMeta { settings, primary_key } = serde_json::from_reader(&mut meta_file)?;
+        let DumpMeta {
+            settings,
+            primary_key,
+        } = serde_json::from_reader(&mut meta_file)?;
         let settings = settings.check();
         let index = Self::open(&dst_dir_path, size as usize)?;
         let mut txn = index.write_txn()?;
@@ -96,15 +102,21 @@ impl Index {
         index.update_settings_txn(&mut txn, &settings, handler.update_builder(0))?;
 
         let document_file_path = src.as_ref().join(DATA_FILE_NAME);
-        let document_file = File::open(&document_file_path)?;
+        let reader = File::open(&document_file_path)?;
+        let mut reader = BufReader::new(reader);
+        reader.fill_buf()?;
+        // If the document file is empty, we don't perform the document addition, to prevent
+        // a primary key error to be thrown.
+        if !reader.buffer().is_empty() {
             index.update_documents_txn(
                 &mut txn,
                 JsonStream,
                 IndexDocumentsMethod::UpdateDocuments,
-            Some(document_file),
+                Some(reader),
                 handler.update_builder(0),
                 primary_key.as_deref(),
             )?;
+        }
 
         txn.commit()?;
 

meilisearch-http/src/index_controller/dump_actor/loaders/v1.rs

@@ -1,10 +1,4 @@
-use std::{
-    collections::{BTreeMap, BTreeSet},
-    fs::File,
-    marker::PhantomData,
-    path::Path,
-    sync::Arc,
-};
+use std::{collections::{BTreeMap, BTreeSet}, fs::File, io::BufRead, marker::PhantomData, path::Path, sync::Arc};
 
 use heed::EnvOpenOptions;
 use log::{error, info, warn};
@@ -103,8 +97,9 @@ fn load_index(
 
     let update_builder = UpdateBuilder::new(0);
     let file = File::open(&src.as_ref().join("documents.jsonl"))?;
-    let reader = std::io::BufReader::new(file);
-
+    let mut reader = std::io::BufReader::new(file);
+    reader.fill_buf()?;
+    if !reader.buffer().is_empty() {
         index.update_documents(
             UpdateFormat::JsonStream,
             IndexDocumentsMethod::ReplaceDocuments,
@@ -112,6 +107,7 @@ fn load_index(
             update_builder,
             primary_key,
         )?;
+    }
 
     // the last step: we extract the original milli::Index and close it
     Arc::try_unwrap(index.0)