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Recovery

Learn point-in-time recovery.

Recovery

Recovery restores damaged or deleted data from a backup. Point-in-time recovery (PITR) rolls data back to a specific moment; WAL logs make it possible.

COPY orders FROM '/tmp/orders.csv';
-- PITR: WAL logları belirli ana kadar yürütülür

PITR restores to a specific moment.

Recovery — details

During restore the database is unavailable. In PITR a full backup is loaded first, then WAL records are replayed in order. The target time stops the WAL replay.

Practice Recovery

Restore the orders table from /tmp/orders.csv: COPY orders FROM '/tmp/orders.csv'.

Starter code

query.sql
-- recovery
COPY orders

Sample solution

query.sql
COPY orders FROM '/tmp/orders.csv';

Expected output

COPY 5

Questions and answers

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

1 Import

Question 
COPY orders FROM '____';
Answer 
COPY orders FROM '/tmp/orders.csv';

Explanation: /tmp/orders.csv is the right answer.

2 Recovery: match the terms

Term Meaning
recovery recovery
PITR point-in-time
WAL log
restore restore

3 What does PITR provide?

  • Less disk space
  • Restoring to a specific point in time Correct answer
  • Faster writes
  • Column compression

Explanation: PITR provides restore to a specific moment.

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