Intermediate LevelPostgreSQL
What is PgBouncer and what are Session, Transaction, and Statement pooling modes?
❓ Interview Prompt: Explain PgBouncer connection pooler, reducing process fork overhead, Session pooling vs Transaction pooling vs Statement pooling.
Because PostgreSQL forks a dedicated OS process per connection, maintaining thousands of open client connections causes thread context-switching overhead and memory exhaustion. PgBouncer is a high-performance proxy pooler:
3 Pooling Modes:
1
Session Pooling: Assigns a server connection for the full duration of a client login session.
2
Transaction Pooling (Recommended): Assigns a server connection ONLY for the duration of a transaction ('BEGIN' ... 'COMMIT'). Allows 100 server connections to serve 10,000 client apps!
3
Statement Pooling: Assigns a server connection per single SQL statement.
Code Implementation Example
ini
; pgbouncer.ini configuration
[databases]
ecommerce = host=127.0.0.1 port=5432 dbname=ecommerce
[pgbouncer]
pool_mode = transaction
max_client_conn = 5000
default_pool_size = 50💡Configuring PgBouncer transaction pooling mode.
🎯 Interview Key Takeaway
Use PgBouncer in Transaction pooling mode to support thousands of application connections with low server memory.
#PgBouncer#Connection Pooling#Transaction Mode#Intermediate
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