diff --git a/.github/workflows/test.yaml b/.github/workflows/test.yaml
index 5bbf20e..2b39d07 100644
--- a/.github/workflows/test.yaml
+++ b/.github/workflows/test.yaml
@@ -36,6 +36,17 @@ jobs:
       - name: Run unit tests
         run: tox run -- --cov-report=term
 
+  test-db:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Install Lets
+        uses: lets-cli/lets-action@v1.1
+        with:
+          version: latest
+      - name: Test database integration
+        run: timeout 600 lets test-pg
+
   federation-test:
     runs-on: ubuntu-latest
     steps:
diff --git a/hiku/sources/aiopg.py b/hiku/sources/aiopg.py
index b5cd606..e354f21 100644
--- a/hiku/sources/aiopg.py
+++ b/hiku/sources/aiopg.py
@@ -37,16 +37,14 @@ def in_impl(
     def select_expr(
         self, fields_: List[Field], ids: Iterable
     ) -> Tuple[Select, Callable]:
-        visited = set()
-        columns = []
-        query_columns = []
-        for f in fields_:
-            column = self.from_clause.c[f.name]
-            columns.append(column)
-
-            if f.name not in visited and column != self.primary_key:
-                visited.add(f.name)
-                query_columns.append(column)
+        result_columns = [self.from_clause.c[f.name] for f in fields_]
+        # aiopg requires unique columns to be passed to select,
+        # otherwise it will raise an error
+        query_columns = [
+            column
+            for f in _uniq_fields(fields_)
+            if (column := self.from_clause.c[f.name]) != self.primary_key
+        ]
 
         expr = (
             sqlalchemy.select(
@@ -58,7 +56,7 @@ def select_expr(
 
         def result_proc(rows: List[_sa.Row]) -> List:
             rows_map = {
-                row[self.primary_key]: [row[c] for c in columns]
+                row[self.primary_key]: [row[c] for c in result_columns]
                 for row in map(_sa._process_result_row, rows)
             }
 
diff --git a/lets.yaml b/lets.yaml
index cfdff27..78acd61 100644
--- a/lets.yaml
+++ b/lets.yaml
@@ -57,7 +57,7 @@ commands:
   test-pg:
     description: Run tests with pg
     depends: [_build-tests]
-    cmd: [docker-compose, run, --rm, test-pg]
+    cmd: [docker compose, run, --rm, test-pg]
 
   test-tox:
     description: Run tests using tox