PostgreSQL EXPLAIN ANALYZE: Reading Query Plans Like a Pro

The article you've shared provides a comprehensive guide on how to use EXPLAIN ANALYZE in PostgreSQL for diagnosing and optimizing slow SQL queries. Here are the key points summarized:

Key Concepts

1. Understanding Query Execution Plans:

   • The EXPLAIN command shows the execution plan of a query.
   • ANALYZE option runs the actual query to gather real-time statistics.

2. Common Issues Identified by EXPLAIN ANALYZE:

   • Sequential Scans on Large Tables: Indicates that PostgreSQL is scanning entire tables rather than using indexes efficiently.
   • Nested Loops with Many Rows: Suggests inefficient joins, often due to lack of proper indexing or join conditions.
   • Estimate vs. Actual Row Counts: Significant discrepancies between estimated and actual row counts can indicate outdated statistics.

3. Buffers Option:

   • The BUFFERS option in EXPLAIN ANALYZE provides insights into how many times data was read from disk versus served from memory (shared_buffers). High disk reads suggest inefficiencies or insufficient RAM.

Practical Workflow

1. Step 1: Get the Plan with Buffers

   sql
    
   1EX

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