Overwrite limit_clause in TrinoSQLCompiler (#37)

Overwrite limit_clause in TrinoSQLCompiler

sqlalchemy_trino/compiler.py

@@ -80,7 +80,18 @@
 
 
 class TrinoSQLCompiler(compiler.SQLCompiler):
-    pass
+
+    def limit_clause(self, select, **kw):
+        """
+        Trino support only OFFSET...LIMIT but not LIMIT...OFFSET syntax.
+        See https://github.com/trinodb/trino/issues/4335.
+        """
+        text = ""
+        if select._offset_clause is not None:
+            text += " OFFSET " + self.process(select._offset_clause, **kw)
+        if select._limit_clause is not None:
+            text += "\n LIMIT " + self.process(select._limit_clause, **kw)
+        return text
 
 
 class TrinoDDLCompiler(compiler.DDLCompiler):

tests/test_compiler.py

@@ -0,0 +1,29 @@
+from sqlalchemy import Table, MetaData, Column, Integer, String, select
+
+from sqlalchemy_trino.dialect import TrinoDialect
+
+metadata = MetaData()
+table = Table(
+    'table',
+    metadata,
+    Column('id', Integer, primary_key=True),
+    Column('name', String),
+)
+
+
+def test_limit_offset():
+    statement = select(table).limit(10).offset(0)
+    query = statement.compile(dialect=TrinoDialect())
+    assert str(query) == 'SELECT "table".id, "table".name \nFROM "table" OFFSET :param_1\n LIMIT :param_2'
+
+
+def test_limit():
+    statement = select(table).limit(10)
+    query = statement.compile(dialect=TrinoDialect())
+    assert str(query) == 'SELECT "table".id, "table".name \nFROM "table"\n LIMIT :param_1'
+
+
+def test_offset():
+    statement = select(table).offset(0)
+    query = statement.compile(dialect=TrinoDialect())
+    assert str(query) == 'SELECT "table".id, "table".name \nFROM "table" OFFSET :param_1'