feat(duckdb): add attach and detach methods for adding and removi…

…ng databases to the current duckdb session

ibis/backends/duckdb/__init__.py

@@ -764,6 +764,44 @@ def read_sqlite(self, path: str | Path, table_name: str | None = None) -> ir.Tab
 
         return self.table(table_name)
 
+    def attach(
+        self, path: str | Path, name: str | None = None, read_only: bool = False
+    ) -> None:
+        """Attach another DuckDB database to the current DuckDB session.
+
+        Parameters
+        ----------
+        path
+            Path to the database to attach.
+        name
+            Name to attach the database as. Defaults to the basename of `path`.
+        read_only
+            Whether to attach the database as read-only.
+        """
+        code = f"ATTACH '{path}'"
+
+        if name is not None:
+            name = sg.to_identifier(name).sql(self.name)
+            code += f" AS {name}"
+
+        if read_only:
+            code += " (READ_ONLY)"
+
+        with self.begin() as con:
+            con.exec_driver_sql(code)
+
+    def detach(self, name: str) -> None:
+        """Detach a database from the current DuckDB session.
+
+        Parameters
+        ----------
+        name
+            The name of the database to detach.
+        """
+        name = sg.to_identifier(name).sql(self.name)
+        with self.begin() as con:
+            con.exec_driver_sql(f"DETACH {name}")
+
     def attach_sqlite(
         self, path: str | Path, overwrite: bool = False, all_varchar: bool = False
     ) -> None:

ibis/backends/duckdb/tests/test_client.py

@@ -70,8 +70,7 @@ def test_cross_db(tmpdir):
     con2 = ibis.duckdb.connect(path2)
     t2 = con2.create_table("t2", schema=ibis.schema(dict(x="int")))
 
-    with con2.begin() as c:
-        c.exec_driver_sql(f"ATTACH '{path1}' AS test1 (READ_ONLY)")
+    con2.attach(path1, name="test1", read_only=True)
 
     t1_from_con2 = con2.table("t1", schema="test1.main")
     assert t1_from_con2.schema() == t2.schema()
@@ -80,3 +79,37 @@ def test_cross_db(tmpdir):
     foo_t1_from_con2 = con2.table("t1", schema="test1.foo")
     assert foo_t1_from_con2.schema() == t2.schema()
     assert foo_t1_from_con2.execute().equals(t2.execute())
+
+
+def test_attach_detach(tmpdir):
+    import duckdb
+
+    path1 = str(tmpdir.join("test1.ddb"))
+    with duckdb.connect(path1):
+        pass
+
+    path2 = str(tmpdir.join("test2.ddb"))
+    con2 = ibis.duckdb.connect(path2)
+
+    # default name
+    name = "test1"
+    assert name not in con2.list_databases()
+
+    con2.attach(path1)
+    assert name in con2.list_databases()
+
+    con2.detach(name)
+    assert name not in con2.list_databases()
+
+    # passed-in name
+    name = "test_foo"
+    assert name not in con2.list_databases()
+
+    con2.attach(path1, name=name)
+    assert name in con2.list_databases()
+
+    con2.detach(name)
+    assert name not in con2.list_databases()
+
+    with pytest.raises(sa.exc.ProgrammingError):
+        con2.detach(name)