Day 8: Cassandra Lab Practice – Batch Operations

✅ Day 8: Batch Operations in Cassandra

🎯 Objective:

Learn how to perform multiple inserts, updates, or deletes in a single batch using the BATCH statement in CQL.

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📘 1. What is a Batch?

• A BATCH lets you group multiple CQL statements into a single request.
• Use carefully — it is not meant for high-performance mass inserts.
• Best use case: multiple updates on the same partition key.

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🧩 2. Basic Batch Syntax

BEGIN BATCH
  <insert/update/delete statement 1>;
  <insert/update/delete statement 2>;
APPLY BATCH;

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🧪 3. Example: Batch Insert into employee Table

BEGIN BATCH
  INSERT INTO test_lab.employee (emp_id, name, department, joined_on)
  VALUES (uuid(), 'Ravi', 'HR', toTimestamp(now()));

  INSERT INTO test_lab.employee (emp_id, name, department, joined_on)
  VALUES (uuid(), 'Meera', 'Finance', toTimestamp(now()));
APPLY BATCH;

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🔧 4. Example: Batch Update

BEGIN BATCH
  UPDATE test_lab.employee
  SET department = 'Tech'
  WHERE emp_id = <UUID1>;

  UPDATE test_lab.employee
  SET department = 'Admin'
  WHERE emp_id = <UUID2>;
APPLY BATCH;

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⚠️ 5. Best Practices for Batch

Good Practice	Bad Practice
Same partition key	Different partition keys
Small number of statements (3–5)	Very large batches (>50)
Related operations (atomic update)	Massive bulk loading

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🛑 6. What Happens on Error?

• If any query in batch fails, the entire batch is aborted.
• Always validate queries individually before batching.

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🧪 Day 8 Lab Tasks

1. Use BATCH to insert 2–3 employees
2. Update multiple rows using a batch
3. Try inserting into different tables in one batch
4. Observe performance and error handling

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✅ Checklist

Task	Done
Used BEGIN BATCH ... APPLY BATCH	✅
Inserted multiple rows in one batch	✅
Performed batch updates	✅
Understood batch best practices	✅