PgCache is a smart read replica for PostgreSQL that caches the hot data driving most of your traffic. Stop paying to replicate cold data. Try it for free on a small workload, then scale as you grow. Change one connection string. Never serves stale data.
If you're using traditional read replicas to scale PostgreSQL, you may be paying to duplicate far more data than your workload actually needs. That means more always-on compute, more storage, more transfer cost, and more operational overhead. PgCache takes a simpler approach.
The Pareto Advantage
PgCache acts as a demand-driven proxy in front of PostgreSQL. It automatically caches the queries and data that are used most often, so you can get the benefits of a read replica without duplicating your full database footprint. The result is faster reads and lower infrastructure waste.
Drop-In Deployment
PgCache is a wire-compatible PostgreSQL proxy. Just update your connection string. No application code changes, no Redis layer, and no separate cache invalidation logic. Uncacheable queries pass through transparently to your origin database.
Always Fresh
PgCache uses PostgreSQL logical replication to keep cached data synchronized with the source database. Writes continue to go directly to your origin database, while reads are served from cache when possible. That means you can reduce stale-cache risk without adding complexity to your application.
Works With Your Existing Stack
PgCache works with PostgreSQL 16, 17, and 18, and supports any ORM or driver that speaks the PostgreSQL wire protocol. It handles parameterized queries, JOINs, aggregations, GROUP BY, DISTINCT, and window functions. If your app runs on Postgres, PgCache can fit into your existing stack.
Pricing That Scales With You
Start with a free small instance or 30-day free trial to test PgCache on a real workload before committing. After that, PgCache uses a flat monthly software fee per instance, making costs predictable and easy to budget.
Cache the 20%, Offload the 80%: Automatically identifies and caches hot query data using demand-driven logic. Stop brute-force scaling and paying to replicate 100% of your cold data.
Always Fresh, Never Stale: PostgreSQL Logical Replication (CDC) keeps cached data perfectly in sync in real time. No TTL guesses, no stale reads, no cache invalidation logic in your application.
Test for Free on a Small Workload, then enjoy Simple Flat Monthly Pricing. No per-query charges, no surprise bills. Running at scale? Contact us for a private offer.
AWS Marketplace now accepts line of credit payments through the PNC Vendor Finance program. This program is available to select AWS customers in the US, excluding NV, NC, ND, TN, & VT.
Try this product free for 30 days according to the free trial terms set by the vendor. Usage-based pricing is in effect for usage beyond the free trial terms. Your free trial gets automatically converted to a paid subscription when the trial ends, but may be canceled any time before that.
You pay by the hour based on the EC2 instance size you run PgCache on. Six instance options are available: t4g.small, m6g.medium, m6g.large, m6g.xlarge, m6g.2xlarge, and m6g.4xlarge. These are not feature tiers. They differ only in compute capacity, so pricing scales up as you pick a larger instance to match your workload. You choose the size that fits your read traffic. Billing is usage-based and hourly, with no per-query charges and no monthly software fee. Run it continuously for a predictable, forecastable cost.
Top-of-mind questions for buyers
What does the hourly instance charge actually pay for, and what runs on it?
You pay for one running instance that acts as a caching proxy between your application and your PostgreSQL database. Each instance size maps to a set amount of compute. The proxy caches the hot data your traffic touches, so a larger instance handles more read traffic and cached working set.
Am I charged when the instance is stopped, and are there extra per-query fees?
Billing meters running instance-hours, so a stopped instance stops accruing software charges. There are no per-query charges and no monthly software fee. Underlying AWS storage may still bill separately while an instance is stopped. Run it continuously for a flat, forecastable line item.
How do I pick an instance size, and what happens if my read traffic grows?
Choose the instance size that matches your read workload; the six options differ only in compute capacity, not features. If traffic grows, you switch to a larger instance and your hourly rate follows that size. The change is manual — you select the new size when you deploy.
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An AMI is a virtual image that provides the information required to launch an instance. Amazon EC2 (Elastic Compute Cloud) instances are virtual servers on which you can run your applications and workloads, offering varying combinations of CPU, memory, storage, and networking resources. You can launch as many instances from as many different AMIs as you need.
Version release notes
PgCache v0.6.2 - 2026-07-03
Reliability
Slow populations no longer hold coalesced waiters hostage - when concurrent requests coalesce onto a single in-flight population, a waiter whose population runs past a forward deadline is now degraded to origin while the population completes in the background.
Performance
More precise CDC invalidation under REPLICA IDENTITY FULL - UPDATE and DELETE events are now probed against the recovered old-row values rather than a primary-key-only wildcard, so changes to joined tables invalidate fewer cached queries.
Candidate-narrowed CDC invalidation and memo eviction - the invalidation and in-process memo-eviction passes now run against the per-operation candidate sets produced by the shared constraint-containment probe, replacing full-set scans.
Lower CDC apply overhead - the per-event CDC hot path was reworked to avoid unnecessary work and allocations.
Lower population and escaping overhead - population row tuples and string literals are escaped directly into the output buffer without per-column or temporary strings.
More precise LIMIT-window maintenance - an UPDATE to a column in the sort key of a cached query is now maintained in place within the LIMIT window and is gated on the changed row matching the query predicate.
Additional details
Usage instructions
PgCache AMI Usage
PgCache is a transparent caching proxy for PostgreSQL. This AMI includes PgCache and an embedded PostgreSQL 18 cache database, managed as systemd services. On first boot, a bootstrap script fetches your database credentials from AWS SSM Parameter Store and starts the proxy.
Prerequisites
Origin PostgreSQL database with wal_level = logical enabled
Database user with REPLICATION role attribute or superuser
IAM role attached to the instance with ssm:GetParameter permission
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PgCache is a drop-in Postgres query cache that accelerates cloud database performance without code changes. Our wire-compatible proxy sits between your application and database, automatically caching frequently accessed data and using Change Data Capture (CDC) to eliminate stale data concerns. Designed specifically for Postgres, PgCache delivers 80%+ latency improvements while reducing database load and costs. Perfect for scaling applications experiencing cloud database bottlenecks.
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