PostgreSQL sizing

PostgreSQL Sizing for CPU, Memory, Storage, and Connections

PostgreSQL sizing is not picking the largest cloud instance you can afford. It is matching CPU, memory, I/O, storage growth, and connection behavior to the workload you actually run.

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postgresql sizingpg sizingpostgres server sizingpostgresql capacity planningpostgresql memory sizing

Signals Worth Watching

CPU is saturated while the top queries are CPU-heavy

Cache hit ratio drops as the working set outgrows memory

Temp files and sort spills rise during peak traffic

WAL generation grows faster than archive and replica capacity

Connection count drives memory pressure before query work begins

Practical PostgreSQL Checks

Read the current memory and connection shape

Memory sizing has to account for shared memory, OS cache, and per-query memory multiplied by concurrency.

SELECT name, setting, unit
FROM pg_settings
WHERE name IN ('max_connections','shared_buffers','work_mem','maintenance_work_mem','effective_cache_size')
ORDER BY name;

Estimate I/O pressure from the workload

A bigger instance will not fix a query pattern that keeps reading unnecessary blocks. Sizing and tuning should be read together.

SELECT query, calls, shared_blks_read, shared_blks_hit, temp_blks_written
FROM pg_stat_statements
ORDER BY shared_blks_read DESC
LIMIT 20;

How MonPG Helps

MonPG shows CPU, memory, I/O, connection, temp file, and WAL pressure next to query workload.

Historical trends help separate one bad release from steady capacity growth.

Cloud-specific pages help teams reason about RDS, Aurora, Azure, Cloud SQL, and self-hosted PostgreSQL differently.

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Documentation for This Topic

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