CompositeReaderConfig.java

@Configuration
public class CompositeReaderConfig {
  @Bean
  public ItemReader<CustomerAccount> compositeReader(DataSource customerDS,
      @Qualifier("accountDataSource") DataSource accountDS, PagingQueryProvider queryProvider) {
    CompositeJdbcPagingItemReader<CustomerAccount> reader = new CompositeJdbcPagingItemReader<>();
    reader.setDataSource(accountDS);
    reader.setPageSize(10);
    reader.setQueryProvider(queryProvider);
    reader.setRowMapper(new BeanPropertyRowMapper<>(CustomerAccount.class));
    CustomerAccountPageProcessor processor = new CustomerAccountPageProcessor();
    processor.setDataSource(customerDS);
    reader.setPageProcessor(processor);
    return reader;
  }

  @Bean
  public SqlPagingQueryProviderFactoryBean queryProvider(@Qualifier("accountDataSource") DataSource accountDS) {
    SqlPagingQueryProviderFactoryBean bean = new SqlPagingQueryProviderFactoryBean();
    bean.setDataSource(accountDS);
    bean.setSelectClause("SELECT *");
    bean.setFromClause("FROM customer_account");
    bean.setSortKey("id");
    return bean;
  }
}