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Index maintenance

Learn rebuild and analyze.

Index maintenance

Indexes bloat and fragment over time. REINDEX rebuilds from scratch; VACUUM clears dead rows; ANALYZE refreshes statistics.

REINDEX INDEX idx_products_name;
VACUUM ANALYZE products;

Maintenance uses three commands.

Index maintenance — details

On write-heavy tables, a weekly REINDEX makes sense. PostgreSQL REINDEX CONCURRENTLY avoids locks and keeps the application running.

Practice Index maintenance

Run REINDEX INDEX to rebuild the idx_products_name index.

Starter code

query.sql
-- index maintenance
REINDEX

Sample solution

query.sql
REINDEX INDEX idx_products_name;

Expected output

REINDEX

Questions and answers

Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.

1 Rebuild the index

Question 
REINDEX INDEX ____
Answer 
REINDEX INDEX idx_products_name

Explanation: idx_products_name is the right answer.

2 Index maintenance: match the terms

Term Meaning
REINDEX rebuild
VACUUM clean
ANALYZE stats
bloat bloat

3 What does REINDEX do?

  • Rebuilds the index Correct answer
  • Drops the table
  • Collects statistics
  • Takes a backup

Explanation: REINDEX rebuilds the index.

All lessons in Expert

1 Database design

  1. ER model
  2. Cardinality
  3. Surrogate keys
  4. Natural keys
  5. Denormalization
  6. Summary - Design

2 Index tuning

  1. B-tree structure
  2. Covering index
  3. Partial index
  4. Index selectivity
  5. Index maintenance
  6. Summary - Index tuning

3 Query optimizer

  1. What is an optimizer?
  2. Statistics
  3. Cost model
  4. Join strategies
  5. Plan cache
  6. Summary - Optimizer

4 Project: Performance tuning

  1. Scenario design
  2. Reading plans
  3. Adding indexes
  4. Rewriting queries
  5. Comparing results

5 Replication and sharding

  1. What is replication?
  2. Master-slave
  3. Sync vs async
  4. What is sharding?
  5. Shard key
  6. Summary - Replication and sharding

6 Distributed and big data

  1. Distributed queries
  2. MPP
  3. Columnar storage
  4. SQL on Hadoop
  5. SQL vs NoSQL
  6. Summary - Distributed and big data

7 Security and backup

  1. SQL injection
  2. Parameterised queries
  3. Authorisation
  4. Backup
  5. Recovery
  6. Summary - Security and backup

8 Expert final

  1. Design challenge
  2. Optimization challenge
  3. Security challenge
  4. Backup challenge