Design for Server Side Pagination

In previous article, we have discussed about various type of pagination and that how these work. We have seen that in most of the scenarios, server side pagination is better than client side pagination. Client side pagination can be used only if data, i.e. the number of records, are limited. In that case, we can consider to load all data on client side and may divide the data in pages while showing on screen. However, if data is large, we would prefer the server side pagination.

In this article, we shall discuss how we can design the server side pagination component. At first, let us summarize the requirements for server side pagination.

  • Data is large enough to support the needs of server side pagination implementation, as discussed in previous article.
  • Only current page of data (or may be 1-2 more pages) should be loaded from data repository (DB), so we want to reduce the need to load large amount of data from data repository. The same or lesser amount of data should be loaded on client side.
  • User can navigate  through the pages using next, previous, first or last page kind of actions. 
  • User can also perform 'sort' and 'search' kind of operation on the data.  
With above requirements, let us design the Pagination Component now. 

Analysis and HLD

After analysis of above requirements, following are the main design requirements:
  1. Client - Any software program which needs to retrieve the large amount of data, but want to present this to end user (or application) in pages. Client can be a UI which is showing listing of data to end user, or may be a command line tool to show the data. 
  2. We need a component which 
    1. Can maintain the state for each client. Various states needs to be maintained are: 
      1. Current Page for which data is returned last time to client
      2. Number of records to be returned for one page
      3. Various data retrieval attributes required for fetching the page data from Data Repository, using data access component. These can be 
        1. Criteria to select the desired data 
        2. Sort criteria
        3. Search criteria
        4. etc
    1. Can work as a channel to retrieve the data from repository using data access components
    2. Can provide utility methods to client for accessing the data pages based on user requests like, next | previous | first | last | specific page number
    3. Can provide methods to client using which client can change various data retrieval attributes. This is to support the scenario, when end user change the search or sort criteria at UI.
  1. We need an abstract data access layer (can call it pagination data provider), which can understand the  language of pages and can return the filtered, and sorted data for specified page. 
  2. This component can be named as 'Pagination Manager'