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  2. 7. HOT and Index-Only Scans

7. HOT and Index-Only Scans

This chapter describes two features related to the index scan: Heap Only Tuple (HOT) and index-only scans.

Chapter Contents
  • 7.1. Heap Only Tuple (HOT)
  • 7.2. Index-Only Scans
The Internals of PostgreSQL
  • Home
  • 1. DB Cluster, DB and Tables
    • 1.1. Logical Structure of DB Cluster
    • 1.2. Physical Structure of DB Cluster
    • 1.3. Heap Table Structure
    • 1.4. Writing and Reading Tuples
  • 2. Process and Memory Arch.
    • 2.1. Process Architecture
    • 2.2. Memory Architecture
  • 3. Query Processing
    • 3.1. Overview
    • 3.2. Cost Estimation in Single-Table Query
    • 3.3. Creating the Plan Tree of a Single-Table Query
    • 3.4. Executor Performance
    • 3.5. Join Operations
      • 3.5.1. Nested Loop Join
      • 3.5.2. Merge Join
      • 3.5.3. Hash Join
      • 3.5.4. Join Access Paths and Join Nodes
    • 3.6. Creating the Plan Tree of Multiple-Table Query
    • 3.7. Parallel Query
  • 4. Foreign Data Wrappers (FDW)
    • 4.1. Overview
    • 4.2. postgres_fdw
  • 5. Concurrency Control
    • 5.1 Transaction ID
    • 5.2 Tuple Structure
    • 5.3. Inserting, Deleting and Updating Tuples
    • 5.4. Commit Log (clog)
    • 5.5. Transaction Snapshot
    • 5.6. Visibility Check Rules
    • 5.7. Visibility Check
    • 5.8. Preventing Lost Updates
    • 5.9. Serializable Snapshot Isolation
    • 5.10. Maintenance Processes
  • 6. VACUUM Processing
    • 6.1. Outline of Concurrent VACUUM
    • 6.2. Visibility Map
    • 6.3. Freeze Processing
    • 6.4. Removing Unnecessary Clog Files
    • 6.5. Autovacuum Daemon
    • 6.6. Full VACUUM
  • 7. HOT and Index-Only Scans
    • 7.1. Heap Only Tuple (HOT)
    • 7.2. Index-Only Scans
  • 8. Buffer Manager
    • 8.1. Overview
    • 8.2. Buffer Manager Structure
    • 8.3. Buffer Manager Locks
    • 8.4. How the Buffer Manager Works
    • 8.5. Ring Buffer and Local Buffer
    • 8.6. Flushing Dirty Pages
  • 9. Write Ahead Logging (WAL)
    • 9.1. Overview
    • 9.2. Transaction Log and WAL Segment Files
    • 9.3. Internal Layout of WAL Segment
    • 9.4. Internal Layout of XLOG Record
    • 9.5. Writing of XLOG Records
    • 9.6. WAL related processes
    • 9.7. Checkpoint Processing
    • 9.8. Database Recovery
    • 9.9. WAL Segment Files Management
    • 9.10. Continuous Archiving and Archive Logs
  • 10. Online Backup and PITR
    • 10.1. Base Backup
    • 10.2. How Point-in-Time Recovery Works
    • 10.3. timelineId and Timeline History File
    • 10.4. Point-in-Time Recovery with Timeline History File
    • 10.5. Incremental Backup
  • 11. Streaming Replication
    • 11.1. Starting the Streaming Replication
    • 11.2. How to Conduct Streaming Replication
    • 11.3. Managing Multiple-Standby Servers
    • 11.4. Replication Slots
  • 12. Logical Replication
    • 12.1. Overview and Key Concepts
    • 12.2. Starting Logical Replication
    • 12.3. ReorderBuffer Structure
    • 12.4. WAL Data Filtering and Buffering
    • 12.5. Output Plugins: pgoutput
    • 12.6. Sending Message
    • 12.7. Apply Worker
    • 12.8. Restart and Recovery
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