feat: add flag to enable faster manifest paths (#1612)

The new V2 manifest path scheme makes discovering the latest version of
a table constant time on object stores, regardless of the number of
versions in the table. See benchmarks in the PR here:
https://github.com/lancedb/lance/pull/2798

Closes #1583

python/python/lancedb/_lancedb.pyi

@@ -25,6 +25,7 @@ class Connection(object):
         data: pa.RecordBatchReader,
         storage_options: Optional[Dict[str, str]] = None,
         data_storage_version: Optional[str] = None,
+        enable_v2_manifest_paths: Optional[bool] = None,
     ) -> Table: ...
     async def create_empty_table(
         self,
@@ -33,6 +34,7 @@ class Connection(object):
         schema: pa.Schema,
         storage_options: Optional[Dict[str, str]] = None,
         data_storage_version: Optional[str] = None,
+        enable_v2_manifest_paths: Optional[bool] = None,
     ) -> Table: ...
 
 class Table:

python/python/lancedb/db.py

@@ -567,6 +567,7 @@ class AsyncConnection(object):
         *,
         data_storage_version: Optional[str] = None,
         use_legacy_format: Optional[bool] = None,
+        enable_v2_manifest_paths: Optional[bool] = None,
     ) -> AsyncTable:
         """Create an [AsyncTable][lancedb.table.AsyncTable] in the database.
 
@@ -618,6 +619,14 @@ class AsyncConnection(object):
             If True, use the legacy format for the table. If False, use the new format.
             The default is True while the new format is in beta.
             This method is deprecated, use `data_storage_version` instead.
+        enable_v2_manifest_paths: bool, optional, default False
+            Use the new V2 manifest paths. These paths provide more efficient
+            opening of datasets with many versions on object stores.  WARNING:
+            turning this on will make the dataset unreadable for older versions
+            of LanceDB (prior to 0.13.0). To migrate an existing dataset, instead
+            use the
+            [AsyncTable.migrate_manifest_paths_v2][lancedb.table.AsyncTable.migrate_manifest_paths_v2]
+            method.
 
 
         Returns
@@ -761,6 +770,7 @@ class AsyncConnection(object):
                 schema,
                 storage_options=storage_options,
                 data_storage_version=data_storage_version,
+                enable_v2_manifest_paths=enable_v2_manifest_paths,
             )
         else:
             data = data_to_reader(data, schema)
@@ -770,6 +780,7 @@ class AsyncConnection(object):
                 data,
                 storage_options=storage_options,
                 data_storage_version=data_storage_version,
+                enable_v2_manifest_paths=enable_v2_manifest_paths,
             )
 
         return AsyncTable(new_table)

python/python/lancedb/table.py

@@ -2539,3 +2539,34 @@ class AsyncTable:
         List all indices that have been created with Self::create_index
         """
         return await self._inner.list_indices()
+
+    async def uses_v2_manifest_paths(self) -> bool:
+        """
+        Check if the table is using the new v2 manifest paths.
+
+        Returns
+        -------
+        bool
+            True if the table is using the new v2 manifest paths, False otherwise.
+        """
+        return await self._inner.uses_v2_manifest_paths()
+
+    async def migrate_manifest_paths_v2(self):
+        """
+        Migrate the manifest paths to the new format.
+
+        This will update the manifest to use the new v2 format for paths.
+
+        This function is idempotent, and can be run multiple times without
+        changing the state of the object store.
+
+        !!! danger
+
+            This should not be run while other concurrent operations are happening.
+            And it should also run until completion before resuming other operations.
+
+        You can use
+        [AsyncTable.uses_v2_manifest_paths][lancedb.table.AsyncTable.uses_v2_manifest_paths]
+        to check if the table is already using the new path style.
+        """
+        await self._inner.migrate_manifest_paths_v2()

python/python/tests/test_db.py

@@ -13,6 +13,7 @@
 
 import re
 from datetime import timedelta
+import os
 
 import lancedb
 import numpy as np
@@ -413,6 +414,40 @@ async def test_create_exist_ok_async(tmp_path):
     #     await db.create_table("test", schema=bad_schema, exist_ok=True)
 
 
+@pytest.mark.asyncio
+async def test_create_table_v2_manifest_paths_async(tmp_path):
+    db = await lancedb.connect_async(tmp_path)
+    # Create table in v2 mode with v2 manifest paths enabled
+    tbl = await db.create_table(
+        "test_v2_manifest_paths",
+        data=[{"id": 0}],
+        use_legacy_format=False,
+        enable_v2_manifest_paths=True,
+    )
+    assert await tbl.uses_v2_manifest_paths()
+    manifests_dir = tmp_path / "test_v2_manifest_paths.lance" / "_versions"
+    for manifest in os.listdir(manifests_dir):
+        assert re.match(r"\d{20}\.manifest", manifest)
+
+    # Start a table in V1 mode then migrate
+    tbl = await db.create_table(
+        "test_v2_migration",
+        data=[{"id": 0}],
+        use_legacy_format=False,
+        enable_v2_manifest_paths=False,
+    )
+    assert not await tbl.uses_v2_manifest_paths()
+    manifests_dir = tmp_path / "test_v2_migration.lance" / "_versions"
+    for manifest in os.listdir(manifests_dir):
+        assert re.match(r"\d\.manifest", manifest)
+
+    await tbl.migrate_manifest_paths_v2()
+    assert await tbl.uses_v2_manifest_paths()
+
+    for manifest in os.listdir(manifests_dir):
+        assert re.match(r"\d{20}\.manifest", manifest)
+
+
 def test_open_table_sync(tmp_path):
     db = lancedb.connect(tmp_path)
     db.create_table("test", data=[{"id": 0}])