The optimization of user’s SQL-queries is the important problem that occurs when the software systems of the text document corpus processing are created, and these systems are accessed by external users using the web interface. In the systems discussed in this article, the search module is a separate interface component that interacts with the storage (database) by generating and processing of SQL-queries. The user can perform the complex search queries to the information system, which increase the database load. The optimization of the search module with the implementation of indexes in the database is applied. The experiment which included the iterations on forming the queries to the database of Russian poetic texts with a measurement of the query run-time — with indexes and without ones — is conducted; when the query time decreased, the added indexes were saved and the iteration was repeated. The conclusions about the effectiveness of the usage of indexes in the database are made, within the database the structure of literary texts is organized.