support limit with offset

weed/query/engine/select_test.go

@@ -92,6 +92,92 @@ func TestSQLEngine_SelectFromNonExistentTable(t *testing.T) {
 	}
 }
 
+func TestSQLEngine_SelectWithOffset(t *testing.T) {
+	engine := NewTestSQLEngine()
+
+	// Test SELECT with OFFSET only
+	result, err := engine.ExecuteSQL(context.Background(), "SELECT * FROM user_events LIMIT 10 OFFSET 1")
+	if err != nil {
+		t.Fatalf("Expected no error, got %v", err)
+	}
+
+	if result.Error != nil {
+		t.Fatalf("Expected no query error, got %v", result.Error)
+	}
+
+	// Should have fewer rows than total since we skip 1 row
+	// Sample data has 4 rows, so OFFSET 1 should give us 3 rows
+	if len(result.Rows) != 3 {
+		t.Errorf("Expected 3 rows with OFFSET 1 (4 total - 1 offset), got %d", len(result.Rows))
+	}
+}
+
+func TestSQLEngine_SelectWithLimitAndOffset(t *testing.T) {
+	engine := NewTestSQLEngine()
+
+	// Test SELECT with both LIMIT and OFFSET
+	result, err := engine.ExecuteSQL(context.Background(), "SELECT * FROM user_events LIMIT 2 OFFSET 1")
+	if err != nil {
+		t.Fatalf("Expected no error, got %v", err)
+	}
+
+	if result.Error != nil {
+		t.Fatalf("Expected no query error, got %v", result.Error)
+	}
+
+	// Should have exactly 2 rows (skip 1, take 2)
+	if len(result.Rows) != 2 {
+		t.Errorf("Expected 2 rows with LIMIT 2 OFFSET 1, got %d", len(result.Rows))
+	}
+}
+
+func TestSQLEngine_SelectWithOffsetExceedsRows(t *testing.T) {
+	engine := NewTestSQLEngine()
+
+	// Test OFFSET that exceeds available rows
+	result, err := engine.ExecuteSQL(context.Background(), "SELECT * FROM user_events LIMIT 10 OFFSET 10")
+	if err != nil {
+		t.Fatalf("Expected no error, got %v", err)
+	}
+
+	if result.Error != nil {
+		t.Fatalf("Expected no query error, got %v", result.Error)
+	}
+
+	// Should have 0 rows since offset exceeds available data
+	if len(result.Rows) != 0 {
+		t.Errorf("Expected 0 rows with large OFFSET, got %d", len(result.Rows))
+	}
+}
+
+func TestSQLEngine_SelectWithOffsetZero(t *testing.T) {
+	engine := NewTestSQLEngine()
+
+	// Test OFFSET 0 (should be same as no offset)
+	result1, err := engine.ExecuteSQL(context.Background(), "SELECT * FROM user_events LIMIT 3")
+	if err != nil {
+		t.Fatalf("Expected no error for LIMIT query, got %v", err)
+	}
+
+	result2, err := engine.ExecuteSQL(context.Background(), "SELECT * FROM user_events LIMIT 3 OFFSET 0")
+	if err != nil {
+		t.Fatalf("Expected no error for LIMIT OFFSET query, got %v", err)
+	}
+
+	if result1.Error != nil {
+		t.Fatalf("Expected no query error for LIMIT, got %v", result1.Error)
+	}
+
+	if result2.Error != nil {
+		t.Fatalf("Expected no query error for LIMIT OFFSET, got %v", result2.Error)
+	}
+
+	// Both should return the same number of rows
+	if len(result1.Rows) != len(result2.Rows) {
+		t.Errorf("LIMIT 3 and LIMIT 3 OFFSET 0 should return same number of rows. Got %d vs %d", len(result1.Rows), len(result2.Rows))
+	}
+}
+
 func TestSQLEngine_SelectDifferentTables(t *testing.T) {
 	engine := NewTestSQLEngine()