fix(remote): stream create table readers with multipart writes

python/python/lancedb/db.py

@@ -707,9 +707,6 @@ class LanceDBConnection(DBConnection):
         self._namespace_client_properties = namespace_client_properties
         if _inner is not None:
             self._conn = _inner
-            # Native-derived wrappers resolve this in their async reconstruction
-            # path so construction never synchronously re-enters LOOP.
-            self._read_consistency_interval = read_consistency_interval
             self._cached_namespace_client = None
             return
 
@@ -759,14 +756,11 @@ class LanceDBConnection(DBConnection):
         # storage_options.  Also, this class really shouldn't be holding any state
         # beyond _conn.
         self._conn = AsyncConnection(LOOP.run(do_connect()))
-        # Keep property access synchronous so debugger introspection cannot wait on
-        # the background loop while that thread is suspended at a breakpoint.
-        self._read_consistency_interval = read_consistency_interval
         self._cached_namespace_client: Optional[LanceNamespace] = None
 
     @property
     def read_consistency_interval(self) -> Optional[timedelta]:
-        return self._read_consistency_interval
+        return LOOP.run(self._conn.get_read_consistency_interval())
 
     @property
     def session(self) -> Optional[Session]:
@@ -777,16 +771,8 @@ class LanceDBConnection(DBConnection):
         return self._conn.uri
 
     @classmethod
-    def from_inner(
-        cls,
-        inner: LanceDbConnection,
-        read_consistency_interval: Optional[timedelta],
-    ):
-        return cls(
-            None,
-            read_consistency_interval=read_consistency_interval,
-            _inner=inner,
-        )
+    def from_inner(cls, inner: LanceDbConnection):
+        return cls(None, _inner=inner)
 
     def __repr__(self) -> str:
         return f"{self.__class__.__name__}(uri={self._conn.uri!r})"

python/python/lancedb/permutation.py

@@ -226,7 +226,7 @@ class PermutationBuilder:
 
         async def do_execute():
             inner_tbl = await self._async.execute()
-            return await LanceTable.from_inner(inner_tbl)
+            return LanceTable.from_inner(inner_tbl)
 
         return LOOP.run(do_execute())
 

python/python/lancedb/table.py

@@ -2182,15 +2182,11 @@ class LanceTable(Table):
         return self.name
 
     @classmethod
-    async def from_inner(cls, tbl: LanceDBTable):
-        from .db import AsyncConnection, LanceDBConnection
+    def from_inner(cls, tbl: LanceDBTable):
+        from .db import LanceDBConnection
 
         async_tbl = AsyncTable(tbl)
-        inner_conn = tbl.database()
-        read_consistency_interval = await AsyncConnection(
-            inner_conn
-        ).get_read_consistency_interval()
-        conn = LanceDBConnection.from_inner(inner_conn, read_consistency_interval)
+        conn = LanceDBConnection.from_inner(tbl.database())
         return cls(
             conn,
             async_tbl.name,

python/python/tests/test_db.py

@@ -77,23 +77,6 @@ def test_sync_repr_does_not_use_background_loop(tmp_path, monkeypatch):
     assert repr(table) == f"LanceTable(name='test', _conn={db!r})"
 
 
-def test_read_consistency_interval_does_not_use_background_loop(tmp_path, monkeypatch):
-    from lancedb.background_loop import LOOP
-    from lancedb.db import LanceDBConnection
-
-    consistency_interval = timedelta(seconds=5)
-    db = lancedb.connect(tmp_path, read_consistency_interval=consistency_interval)
-    db_from_inner = LanceDBConnection.from_inner(db._inner, consistency_interval)
-
-    def fail_run(*args, **kwargs):
-        raise AssertionError("properties should not use the Python background loop")
-
-    monkeypatch.setattr(LOOP, "run", fail_run)
-
-    assert db.read_consistency_interval == consistency_interval
-    assert db_from_inner.read_consistency_interval == consistency_interval
-
-
 def test_ingest_pd(tmp_path):
     db = lancedb.connect(tmp_path)
 

python/python/tests/test_permutation.py

@@ -6,7 +6,6 @@ import math
 import pytest
 
 from lancedb import DBConnection, Table, connect
-from lancedb.background_loop import LOOP
 from lancedb.permutation import Permutation, Permutations, permutation_builder
 
 
@@ -32,25 +31,6 @@ def test_split_random_ratios(mem_db):
     assert 65 <= split_1_count <= 75  # ~70% ± tolerance
 
 
-def test_execute_does_not_reenter_background_loop(tmp_path, monkeypatch):
-    import threading
-
-    db = connect(tmp_path)
-    tbl = db.create_table("test_table", pa.table({"x": range(10)}))
-    original_run = LOOP.run
-
-    def fail_on_reentry(future):
-        assert threading.current_thread() is not LOOP.thread
-        return original_run(future)
-
-    monkeypatch.setattr(LOOP, "run", fail_on_reentry)
-
-    permutation_tbl = permutation_builder(tbl).execute()
-
-    assert permutation_tbl.count_rows() == 10
-    assert permutation_tbl._conn.read_consistency_interval is None
-
-
 def test_split_random_counts(mem_db):
     """Test random splitting with absolute counts."""
     tbl = mem_db.create_table(

python/python/tests/test_table.py

@@ -6,7 +6,6 @@ import os
 import sys
 import threading
 import warnings
-from concurrent.futures import ThreadPoolExecutor
 from datetime import date, datetime, timedelta
 from time import sleep
 from typing import List
@@ -2125,27 +2124,6 @@ def test_delete(mem_db: DBConnection):
     assert table.to_arrow()["id"].to_pylist() == [1]
 
 
-def test_concurrent_deletes_are_thread_safe(mem_db: DBConnection):
-    num_workers = 8
-    table = mem_db.create_table(
-        "my_table", data=[{"id": row_id} for row_id in range(num_workers)]
-    )
-    barrier = threading.Barrier(num_workers)
-
-    def delete(row_id: int):
-        barrier.wait()
-        return table.delete(f"id = {row_id}")
-
-    with ThreadPoolExecutor(max_workers=num_workers) as pool:
-        results = list(pool.map(delete, range(num_workers)))
-
-    assert all(result.num_deleted_rows == 1 for result in results)
-    assert sorted(result.version for result in results) == list(
-        range(2, num_workers + 2)
-    )
-    assert table.count_rows() == 0
-
-
 def test_delete_expr(mem_db: DBConnection):
     table = mem_db.create_table(
         "my_table",

python/src/table.rs

@@ -745,9 +745,6 @@ impl Table {
 
     #[allow(private_interfaces)]
     pub fn delete(self_: PyRef<'_, Self>, condition: PredicateArg) -> PyResult<Bound<'_, PyAny>> {
-        // Do not hold the Python borrow across the await.  The cloned Rust table
-        // handle is thread-safe and allows deletes on the same Python table to
-        // run concurrently without PyO3 reporting "Already borrowed".
         let inner = self_.inner_ref()?.clone();
         future_into_py(self_.py(), async move {
             let result = match &condition {

rust/lancedb/src/remote/db.rs

@@ -4,6 +4,7 @@
 use std::collections::HashMap;
 use std::sync::Arc;
 
+use arrow_array::RecordBatch;
 use async_trait::async_trait;
 use http::StatusCode;
 use lance_io::object_store::StorageOptions;
@@ -18,13 +19,14 @@ use lance_namespace::models::{
 };
 
 use crate::Error;
+use crate::data::scannable::Scannable;
 use crate::database::{
     CloneTableRequest, CreateTableMode, CreateTableRequest, Database, DatabaseOptions,
     JobDescription, JobInfo, OpenTableRequest, ReadConsistency, TableNamesRequest,
 };
 use crate::error::Result;
 use crate::remote::util::stream_as_body;
-use crate::table::BaseTable;
+use crate::table::{AddDataBuilder, BaseTable};
 
 use super::ARROW_STREAM_CONTENT_TYPE;
 use super::client::{
@@ -693,7 +695,19 @@ impl<S: HttpSend> Database for RemoteDatabase<S> {
     }
 
     async fn create_table(&self, mut request: CreateTableRequest) -> Result<Arc<dyn BaseTable>> {
-        let body = stream_as_body(request.data.scan_as_stream())?;
+        // The create endpoint limits the size of the complete request even though
+        // its body is streamed. Sources without a row-count hint (notably Python
+        // generators / RecordBatchReader) can therefore exceed that limit after
+        // many individually small batches. Create the schema first and feed the
+        // unknown-length source through the multipart insert path instead.
+        let stage_initial_data = request.data.num_rows().is_none();
+        let schema = request.data.schema();
+        let body = if stage_initial_data {
+            let mut empty = RecordBatch::new_empty(schema.clone());
+            stream_as_body(empty.scan_as_stream())?
+        } else {
+            stream_as_body(request.data.scan_as_stream())?
+        };
 
         let identifier = build_table_identifier(
             &request.name,
@@ -764,6 +778,16 @@ impl<S: HttpSend> Database for RemoteDatabase<S> {
             table_identifier,
             version,
         ));
+        table.seed_schema_ref(schema);
+
+        if stage_initial_data {
+            let base_table: Arc<dyn BaseTable> = table.clone();
+            AddDataBuilder::new(base_table, request.data, None)
+                .write_options(request.write_options)
+                .execute()
+                .await?;
+        }
+
         self.table_cache.insert(cache_key, table.clone()).await;
 
         Ok(table)
@@ -1106,7 +1130,7 @@ mod tests {
     use std::sync::atomic::{AtomicUsize, Ordering};
     use std::sync::{Arc, OnceLock};
 
-    use arrow_array::{Int32Array, RecordBatch};
+    use arrow_array::{Int32Array, RecordBatch, RecordBatchIterator};
     use arrow_schema::{DataType, Field, Schema};
     use lance_namespace_impls::{DynamicContextProvider, OperationInfo};
 
@@ -1371,6 +1395,88 @@ mod tests {
         assert_eq!(table.name(), "table1");
     }
 
+    #[tokio::test]
+    async fn test_create_table_streaming_reader_uses_multipart_insert() {
+        let create_count = Arc::new(AtomicUsize::new(0));
+        let multipart_create_count = Arc::new(AtomicUsize::new(0));
+        let insert_count = Arc::new(AtomicUsize::new(0));
+        let complete_count = Arc::new(AtomicUsize::new(0));
+
+        let create_count_c = create_count.clone();
+        let multipart_create_count_c = multipart_create_count.clone();
+        let insert_count_c = insert_count.clone();
+        let complete_count_c = complete_count.clone();
+        let conn = Connection::new_with_handler_and_config(
+            move |request| {
+                let path = request.url().path();
+                let query = request.url().query().unwrap_or("");
+                match path {
+                    "/v1/table/table1/create/" => {
+                        create_count_c.fetch_add(1, Ordering::SeqCst);
+                        http::Response::builder()
+                            .status(200)
+                            .header("phalanx-version", "0.4.0")
+                            .body(String::new())
+                            .unwrap()
+                    }
+                    "/v1/table/table1/multipart_write/create" => {
+                        multipart_create_count_c.fetch_add(1, Ordering::SeqCst);
+                        http::Response::builder()
+                            .status(200)
+                            .body(r#"{"upload_id":"streaming-create"}"#.to_string())
+                            .unwrap()
+                    }
+                    "/v1/table/table1/insert/" => {
+                        assert!(query.contains("upload_id=streaming-create"));
+                        assert!(query.contains("upload_part_id="));
+                        insert_count_c.fetch_add(1, Ordering::SeqCst);
+                        http::Response::builder()
+                            .status(200)
+                            .body(String::new())
+                            .unwrap()
+                    }
+                    "/v1/table/table1/multipart_write/complete" => {
+                        assert!(query.contains("upload_id=streaming-create"));
+                        complete_count_c.fetch_add(1, Ordering::SeqCst);
+                        http::Response::builder()
+                            .status(200)
+                            .body(r#"{"version":2}"#.to_string())
+                            .unwrap()
+                    }
+                    path => panic!("unexpected path: {path}"),
+                }
+            },
+            ClientConfig {
+                max_bytes_per_request: Some(1),
+                ..Default::default()
+            },
+        );
+
+        let schema = Arc::new(Schema::new(vec![Field::new("a", DataType::Int32, false)]));
+        let batches = vec![
+            Ok(RecordBatch::try_new(
+                schema.clone(),
+                vec![Arc::new(Int32Array::from(vec![1, 2, 3]))],
+            )
+            .unwrap()),
+            Ok(RecordBatch::try_new(
+                schema.clone(),
+                vec![Arc::new(Int32Array::from(vec![4, 5, 6]))],
+            )
+            .unwrap()),
+        ];
+        let reader: Box<dyn arrow_array::RecordBatchReader + Send> =
+            Box::new(RecordBatchIterator::new(batches, schema));
+
+        let table = conn.create_table("table1", reader).execute().await.unwrap();
+
+        assert_eq!(table.name(), "table1");
+        assert_eq!(create_count.load(Ordering::SeqCst), 1);
+        assert_eq!(multipart_create_count.load(Ordering::SeqCst), 1);
+        assert!(insert_count.load(Ordering::SeqCst) >= 1);
+        assert_eq!(complete_count.load(Ordering::SeqCst), 1);
+    }
+
     #[tokio::test]
     async fn test_create_table_already_exists() {
         let conn = Connection::new_with_handler(|_| {

rust/lancedb/src/remote/table.rs

@@ -441,6 +441,11 @@ impl<S: HttpSend> RemoteTable<S> {
         }
     }
 
+    /// Seed the schema cache when the caller already has the Arrow schema.
+    pub(crate) fn seed_schema_ref(&self, schema: SchemaRef) {
+        self.schema_cache.seed(schema);
+    }
+
     /// Return a new handle scoped to `branch`, sharing the client but with fresh
     /// caches and version/freshness state (the branch tracks its own latest).
     /// Mirrors `NativeTable`'s handle-per-branch model.
@@ -1470,8 +1475,8 @@ impl<S: HttpSend + 'static> RemoteTable<S> {
         num_partitions: usize,
     ) -> Result<()> {
         debug_assert!(
-            output.rescannable,
-            "multipart inserts require rescannable input for retry support"
+            output.rescannable || num_partitions == 1,
+            "non-rescannable multipart inserts require a single partition"
         );
 
         let plan = Arc::new(
@@ -2105,7 +2110,7 @@ impl<S: HttpSend> BaseTable for RemoteTable<S> {
         let table_schema = self.schema().await?;
         let table_def = TableDefinition::try_from_rich_schema(table_schema.clone())?;
 
-        let num_partitions = if self.server_version.support_multipart_write() {
+        let (num_partitions, use_multipart) = if self.server_version.support_multipart_write() {
             // Peek at the first batch to estimate write partitions (same as
             // NativeTable) and, regardless of `write_parallelism`, to detect a
             // fully empty input. A multipart write creates its upload session
@@ -2115,10 +2120,12 @@ impl<S: HttpSend> BaseTable for RemoteTable<S> {
             // commit and e.g. `mode=overwrite` would be silently dropped. Route
             // empty input through the single-request path instead, which always
             // sends one schema-only request.
+            let unknown_size = add.data.num_rows().is_none();
             let mut peeked = PeekedScannable::new(add.data);
-            let n = match peeked.peek().await {
+            let first_batch = peeked.peek().await;
+            let n = match first_batch.as_ref() {
                 Some(first_batch) => match add.write_parallelism {
-                    Some(parallelism) if parallelism > 1 => parallelism,
+                    Some(parallelism) if parallelism > 1 && peeked.rescannable() => parallelism,
                     Some(_) => 1,
                     None => {
                         let max_partitions =
@@ -2133,10 +2140,14 @@ impl<S: HttpSend> BaseTable for RemoteTable<S> {
                 },
                 None => 1,
             };
+            // Unknown-length readers cannot be sized up-front, so use a
+            // single-partition multipart upload. It remains streaming while
+            // allowing the request body to be split into bounded parts.
+            let use_multipart = first_batch.is_some() && (n > 1 || unknown_size);
             add.data = Box::new(peeked);
-            n
+            (n, use_multipart)
         } else {
-            1
+            (1, false)
         };
 
         let output = add.into_plan(&table_schema, &table_def)?;
@@ -2146,7 +2157,7 @@ impl<S: HttpSend> BaseTable for RemoteTable<S> {
         }
         let _finish = FinishOnDrop(output.tracker.clone());
 
-        if num_partitions > 1 {
+        if use_multipart {
             self.add_multipart(output, num_partitions).await
         } else {
             self.add_single_partition(output).await

rust/lancedb/src/table/optimize.rs

@@ -304,68 +304,6 @@ mod tests {
         assert_eq!(all_values, expected);
     }
 
-    #[tokio::test]
-    async fn test_parallel_compaction_reserves_fragment_ids_once() {
-        let conn = connect("memory://").execute().await.unwrap();
-        let schema = Arc::new(Schema::new(vec![Field::new("i", DataType::Int32, false)]));
-        let batch =
-            RecordBatch::try_new(schema, vec![Arc::new(Int32Array::from_iter_values(0..10))])
-                .unwrap();
-
-        let table = conn
-            .create_table("test_parallel_compaction", batch.clone())
-            .execute()
-            .await
-            .unwrap();
-
-        // Create 64 fragments. With a 20-row target, compaction plans 32 tasks,
-        // which is more than the commit retry limit that used to be exhausted
-        // when each parallel task reserved fragment IDs independently.
-        for _ in 1..64 {
-            table.add(batch.clone()).execute().await.unwrap();
-        }
-
-        // Legacy row IDs require fragment IDs before an index can be remapped.
-        assert!(
-            !table
-                .as_native()
-                .unwrap()
-                .manifest()
-                .await
-                .unwrap()
-                .uses_stable_row_ids()
-        );
-        table
-            .create_index(&["i"], Index::BTree(BTreeIndexBuilder::default()))
-            .execute()
-            .await
-            .unwrap();
-
-        let version_before = table.version().await.unwrap();
-        let stats = table
-            .optimize(OptimizeAction::Compact {
-                options: CompactionOptions {
-                    target_rows_per_fragment: 20,
-                    num_threads: Some(64),
-                    ..Default::default()
-                },
-                remap_options: None,
-            })
-            .await
-            .unwrap()
-            .compaction
-            .unwrap();
-
-        assert_eq!(stats.fragments_removed, 64);
-        assert_eq!(stats.fragments_added, 32);
-        assert_eq!(table.count_rows(None).await.unwrap(), 640);
-        assert_eq!(
-            table.version().await.unwrap(),
-            version_before + 2,
-            "parallel compaction should use one fragment reservation commit and one rewrite commit"
-        );
-    }
-
     #[tokio::test]
     async fn test_optimize_prune_versions() {
         let conn = connect("memory://").execute().await.unwrap();