Day 5: Cassandra Lab Practice – UPDATE, DELETE & TTL (Time To Live)

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✅ Day 5: Update, Delete, and TTL in Cassandra

🎯 Objective:

Learn how to update, delete, and use TTL (Time to Live) for automatic data expiry in Cassandra.

✏️ 1. UPDATE Rows

Use UPDATE to change values of existing records using the primary key.

➤ Syntax:

UPDATE keyspace.table_name
SET column1 = value1, column2 = value2
WHERE partition_key = value [AND clustering_key = value];

✅ Example – Update employee department:

UPDATE test_lab.employee
SET department = 'Finance'
WHERE emp_id = <UUID>;

🗑️ 2. DELETE Rows or Columns

➤ Delete a row:

DELETE FROM test_lab.employee
WHERE emp_id = <UUID>;

➤ Delete a column only:

DELETE department FROM test_lab.employee
WHERE emp_id = <UUID>;

⏳ 3. TTL (Time to Live)

TTL automatically expires data after a certain number of seconds.

➤ Insert with TTL:

INSERT INTO test_lab.employee (emp_id, name, department, joined_on)
VALUES (uuid(), 'Temp User', 'IT', toTimestamp(now()))
USING TTL 60; -- Expires in 60 seconds

➤ Update with TTL:

UPDATE test_lab.employee
USING TTL 30
SET department = 'Support'
WHERE emp_id = <UUID>;

➤ Check TTL:

SELECT TTL(department) FROM test_lab.employee WHERE emp_id = <UUID>;

⚠️ Important Notes:

  • TTL applies per column or entire row, based on how you insert/update.
  • You must use the full primary key when using UPDATE or DELETE.

🧪 Day 5 Lab Tasks

  1. Insert an employee with TTL = 60 seconds
  2. Update an employee's department
  3. Delete one column (department) from a record
  4. Delete an entire record using DELETE FROM
  5. Use SELECT TTL(column) to confirm TTL
  6. Wait and confirm TTL expiry by checking after 1–2 minutes

✅ Checklist

Task Done
Inserted data with TTL ✅
Used UPDATE with primary key ✅
Deleted specific columns and rows ✅
Verified TTL with SELECT TTL() ✅


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