add_fts_index = async (table_name, field_expression, language) => {
  // TBD check that there are no problems with lenght of constraint name
  const sql = `create index "${sqlsanitize(
    table_name
  )}_fts_index" on "${getTenantSchema()}"."${sqlsanitize(
    table_name
  )}" USING GIN (to_tsvector('${
    language || "english"
  }', ${field_expression}));`;
  sql_log(sql);
  await getMyClient().query(sql);
}
Add Full-text search index
@param {string} table_name - table name
@param {string} field_name - list of columns (members of constraint)
@returns {Promise<void>} no result