diff --git a/hydws/datamodel/base.py b/hydws/datamodel/base.py
index a0846d19448fac32430046219a4d76d18142d3db..fff12a5799a787d035072e6813c00032bb25fa44 100644
--- a/hydws/datamodel/base.py
+++ b/hydws/datamodel/base.py
@@ -3,7 +3,8 @@ import functools
 import uuid
 from datetime import datetime
 
-from sqlalchemy import Boolean, Column, DateTime, Float, Integer, String
+from sqlalchemy import (BigInteger, Boolean, Column, DateTime, Float, Integer,
+                        String)
 from sqlalchemy.dialects.postgresql import UUID
 from sqlalchemy.ext.declarative import declared_attr
 from sqlalchemy.orm import declarative_base
@@ -17,7 +18,11 @@ class Base(object):
     @declared_attr
     def __tablename__(cls):
         return cls.__name__.lower()
-    _oid = Column(Integer, primary_key=True, nullable=False, autoincrement=True)
+    _oid = Column(
+        BigInteger,
+        primary_key=True,
+        nullable=False,
+        autoincrement=True)
 
 
 ORMBase = declarative_base(cls=Base)
diff --git a/hydws/datamodel/orm.py b/hydws/datamodel/orm.py
index 9fc2f7f669ac056889194f100bc3460199ae00ca..3f3e708f62f77899b290ff9efcf42b7da4195af8 100644
--- a/hydws/datamodel/orm.py
+++ b/hydws/datamodel/orm.py
@@ -1,4 +1,4 @@
-from sqlalchemy import Boolean, Column, ForeignKey, Index, Integer, String
+from sqlalchemy import BigInteger, Boolean, Column, ForeignKey, Index, String
 from sqlalchemy.orm import relationship
 
 from hydws.datamodel.base import (CreationInfoMixin, EpochMixin, ORMBase,
@@ -73,7 +73,7 @@ class BoreholeSection(EpochMixin('Epoch', epoch_type='finite'),
     description = Column(String)
 
     _borehole_oid = Column(
-        Integer,
+        BigInteger,
         ForeignKey('borehole._oid', ondelete="CASCADE"),
         index=True)
 
@@ -107,7 +107,7 @@ class HydraulicSample(TimeQuantityMixin('datetime', value_nullable=False,
     fluidcomposition = Column(String)
 
     _boreholesection_oid = Column(
-        Integer,
+        BigInteger,
         ForeignKey('boreholesection._oid', ondelete="CASCADE"),
         index=True)
     section = relationship("BoreholeSection", back_populates="hydraulics")
diff --git a/hydws/routers/boreholes.py b/hydws/routers/boreholes.py
index ac1262337069607eb86b9cdd6a41ee9948f12fce..3924167f85c42995a670c940c0cb8346ee95795f 100644
--- a/hydws/routers/boreholes.py
+++ b/hydws/routers/boreholes.py
@@ -141,9 +141,9 @@ def csv_response(data) -> PlainTextResponse:
     return PlainTextResponse(data, media_type='text/csv')
 
 
-@ router.get("/{borehole_id}/sections/{section_id}/hydraulics",
-             response_model=list[HydraulicSampleSchema],
-             response_model_exclude_none=True)
+@router.get("/{borehole_id}/sections/{section_id}/hydraulics",
+            response_model=list[HydraulicSampleSchema],
+            response_model_exclude_none=True)
 async def get_section_hydraulics(borehole_id: uuid.UUID,
                                  section_id: uuid.UUID,
                                  db: DBSessionDep,