Retrieval using collections

How to retrieve data from a collection.

• Retrieve teams for a particular cyclist id from the set.

  cqlsh> SELECT lastname, teams FROM cycling.cyclist_career_teams WHERE id = 5b6962dd-3f90-4c93-8f61-eabfa4a803e2;

  To query a table containing a collection, Cassandra retrieves the collection in its entirety. Keep collections small enough to be manageable because the collection store in memory. Alternatively, construct a data model to replace a collection if it must accommodate large amounts of data.

  Cassandra returns results in an order based on the type of the elements in the collection. For example, a set of text elements is returned in alphabetical order. If you want elements of the collection returned in insertion order, use a list.

  
  
  
• Retrieve events stored in a list from the upcoming calendar for a particular year and month.

  cqlsh> SELECT * FROM cycling.upcoming_calendar WHERE year=2015 AND month=06;

  
  
  

  Note: The order is not alphabetical, but rather in the order of insertion.
• Retrieve teams for a particular cyclist id from the map.

  cqlsh> SELECT lastname, firstname, teams FROM cycling.cyclist_teams WHERE id=5b6962dd-3f90-4c93-8f61-eabfa4a803e2;

  The order of the map output depends on the key type of the map. In this case, the key is an integer type.