Batch idle guard uses or instead of and — premature flush in objects-only batches, throughput degraded #2105

Bug

The idle-guard condition in the automatic batch flusher uses or instead of and, causing premature flushes in batches that contain only objects (no references) or only references (no objects).

Affected files and lines:

• weaviate/collections/batch/sync.py ~line 180
• weaviate/collections/batch/async_.py ~line 228
• weaviate/collections/batch/base.py ~line 437

The condition reads something like:

if len_o == len(self.__batch_objects) or len_r == len(self.__batch_references):
    # flush — nothing changed

In an objects-only batch (no references being added), len_r is always 0 and len(self.__batch_references) is always 0, so the right-hand side of or is always True. This means the idle-guard fires after every sleep tick regardless of whether objects have accumulated — the batch flushes prematurely before reaching batch_size, degrading throughput.

Expected behavior

The guard should use and — a flush is "idle" (nothing changed) only when both the object count and the reference count are unchanged:

if len_o == len(self.__batch_objects) and len_r == len(self.__batch_references):
    # truly idle — flush

Impact

• Objects-only batches never accumulate to batch_size; every sleep tick triggers a flush
• Effective batch size is 1 (or whatever accumulated in a single sleep interval) instead of the configured limit
• Throughput scales with sleep interval, not batch_size