remove ordering by sys.id

src/datachain/catalog/catalog.py

@@ -1325,8 +1325,6 @@ def ls_dataset_rows(
         if offset:
             q = q.offset(offset)
 
-        q = q.order_by("sys__id")
-
         return q.to_db_records()
 
     def signed_url(self, source: str, path: str, client_config=None) -> str:

src/datachain/data_storage/warehouse.py

@@ -215,10 +215,6 @@ def dataset_select_paginated(
         limit = query._limit
         paginated_query = query.limit(page_size)
 
-        if not paginated_query._order_by_clauses:
-            # default order by is order by `sys__id`
-            paginated_query = paginated_query.order_by(query.selected_columns.sys__id)
-
         results = None
         offset = 0
         num_yielded = 0

src/datachain/query/batch.py

@@ -97,7 +97,6 @@ def __call__(
 
         ordered_query = query.order_by(None).order_by(
             PARTITION_COLUMN_ID,
-            "sys__id",
             *query._order_by_clauses,
         )
 

src/datachain/query/dataset.py

@@ -591,10 +591,6 @@ def process_input_query(self, query: Select) -> tuple[Select, list["Table"]]:
             return query, []
         table = self.catalog.warehouse.create_pre_udf_table(query)
         q: Select = sqlalchemy.select(*table.c)
-        if query._order_by_clauses:
-            # we are adding ordering only if it's explicitly added by user in
-            # query part before adding signals
-            q = q.order_by(table.c.sys__id)
         return q, [table]
 
     def create_result_query(
@@ -630,11 +626,6 @@ def q(*columns):
             else:
                 res = sqlalchemy.select(*cols1).select_from(subq)
 
-            if query._order_by_clauses:
-                # if ordering is used in query part before adding signals, we
-                # will have it as order by id from select from pre-created udf table
-                res = res.order_by(subq.c.sys__id)
-
             if self.partition_by is not None:
                 subquery = res.subquery()
                 res = sqlalchemy.select(*subquery.c).select_from(subquery)
@@ -666,13 +657,6 @@ def create_udf_table(self, query: Select) -> "Table":
     def create_result_query(
         self, udf_table, query: Select
     ) -> tuple[QueryGeneratorFunc, list["sqlalchemy.Column"]]:
-        if not query._order_by_clauses:
-            # if we are not selecting all rows in UDF, we need to ensure that
-            # we get the same rows as we got as inputs of UDF since selecting
-            # without ordering can be non deterministic in some databases
-            c = query.selected_columns
-            query = query.order_by(c.sys__id)
-
         udf_table_query = udf_table.select().subquery()
         udf_table_cols: list[sqlalchemy.Label[Any]] = [
             label(c.name, c) for c in udf_table_query.columns

tests/func/test_datasets.py

@@ -775,6 +775,39 @@ def test_types():
         assert r["binary_col"] == [0, 25]
 
 
+def test_dataset_preview_order(test_session):
+    ids = list(range(10000))
+    order = ids[::-1]
+    catalog = test_session.catalog
+    dataset_name = "test"
+
+    DataChain.from_values(id=ids, order=order, session=test_session).order_by(
+        "order"
+    ).save(dataset_name)
+
+    preview_values = []
+
+    for r in catalog.get_dataset(dataset_name).get_version(1).preview:
+        id = ids.pop()
+        o = order.pop()
+        entry = (id, o)
+        preview_values.append((id, o))
+        assert (r["id"], r["order"]) == entry
+
+    DataChain.from_dataset(dataset_name, session=test_session).save(dataset_name)
+
+    for r in catalog.get_dataset(dataset_name).get_version(2).preview:
+        assert (r["id"], r["order"]) == preview_values.pop(0)
+
+    DataChain.from_dataset(dataset_name, 2, session=test_session).order_by("id").save(
+        dataset_name
+    )
+
+    for r in catalog.get_dataset(dataset_name).get_version(3).preview:
+        assert r["id"] == ids.pop(0)
+        assert r["order"] == order.pop(0)
+
+
 def test_dataset_preview_last_modified(cloud_test_catalog, dogs_dataset):
     catalog = cloud_test_catalog.catalog