Hey there! As someone who’s worked with Cassandra for years, let’s walk through your questions about the Map data type clearly and straightforwardly.

1. Supported Data Types for Cassandra Maps #

Cassandra's map is a collection type that stores key-value pairs, with specific rules for valid key and value types:

• Map Keys: Must be immutable native Cassandra types (since keys are hashed for efficient lookups). Valid options include:

  • Numeric types: int, bigint, smallint, tinyint, float, double, decimal
  • String types: text, varchar
  • Date/time types: timestamp, date, time
  • Identifier types: uuid, timeuuid
  • Network type: inet
  • Boolean type: boolean
    Note: Mutable types like collections, user-defined types (UDTs), or tuples can’t be used as map keys.

• Map Values: Far more flexible—you can use any native Cassandra type, including all the ones listed above, plus collections (list, set, map), UDTs, tuples, and even frozen collections/UDTs.

2. Validity of the login_user Table with map<timestamp, text> #

Great news: Your table creation statement is 100% valid!

timestamp is a perfectly acceptable immutable type for map keys, and text is a standard, valid type for map values. Let’s confirm with your exact code:

CREATE TABLE login_user ( 
    user_name text, 
    password text, 
    location map<timestamp,text>, 
    PRIMARY KEY (user_name) 
);

This will work exactly as you intend. A quick heads-up: Since map keys are unique per row, if you insert a new entry into the location map with a timestamp that already exists for a user, it will overwrite the existing text value for that key. That’s standard Cassandra collection behavior—just something to keep in mind as you work with the table.

内容的提问来源于stack exchange，提问作者Inuri Jayanika Ginige