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Databases · head to head

FaunaDB vs Microsoft SQL Server

FaunaDB logo

FaunaDB

Databases

Document-relational database whose hosted service closed in 2025 and whose core is now unmaintained Apache 2.0 code.

From
Free
Rated
-
Full reviewWebsite
Microsoft SQL Server logo

Microsoft SQL Server

Databases

Enterprise-grade relational database management system

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: FaunaDB the hosted service was wound down in 2025, so there is no managed Fauna to buy; every remaining user either operates a JVM cluster themselves or migrates, and both are projects rather than tasks.; Microsoft SQL Server licensing and on-premises deployment costs are high compared to open-source alternatives, with Enterprise Edition exceeding $60,000 for minimum core requirements
  • They diverge on capability: FaunaDB covers Document-relational model, Microsoft SQL Server covers T-SQL.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which FaunaDB and Microsoft SQL Server actually diverge.

Attributes where FaunaDB and Microsoft SQL Server differ
AttributeFaunaDBMicrosoft SQL Server
Pricing modelfreemiumUnknown
PlatformsWebWindows Server, Linux (RHEL, SUSE, Ubuntu), Docker, Azure
Founded20121989

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated), category (Databases).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in FaunaDB

  • Document-relational model
  • FQL v10
  • Distributed ACID transactions
  • HTTPS access
  • User-defined functions
  • Attribute-based access control
  • Document history
  • Event streaming

Only in Microsoft SQL Server

  • T-SQL
  • ACID Compliance
  • Advanced Security
  • In-memory OLTP
  • Columnstore Indexes
  • Always On Availability
  • Machine Learning Services
  • Azure

What people use each for

The jobs each tool is most often brought in to do.

FaunaDB

  • Keeping an existing Fauna-backed application alive on self-hosted infrastructure while a migration is planned and fundednot Microsoft SQL Server
  • Extracting historical data from a Fauna dataset that can no longer be reached through the hosted APInot Microsoft SQL Server
  • Studying a production implementation of deterministic distributed transactions, since the full server source is now readable under Apache 2.0not Microsoft SQL Server
  • Forking the engine deliberately, where an organisation has JVM and distributed-systems staff and wants a document-relational store it fully controlsnot Microsoft SQL Server

Microsoft SQL Server

  • Transaction processingnot FaunaDB
  • Data storagenot FaunaDB
  • Application backendnot FaunaDB
  • Reportingnot FaunaDB
  • Data analyticsnot FaunaDB

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

FaunaDB

  • The hosted service was wound down in 2025, so there is no managed Fauna to buy; every remaining user either operates a JVM cluster themselves or migrates, and both are projects rather than tasks.
  • The open-sourced repository has had no substantive activity since May 2025 and the drivers were frozen alongside it, so you inherit responsibility for security patches in a Scala distributed database that almost nobody else is running.
  • FQL has no wire or dialect compatibility with anything else, so migrating off is a rewrite of every query, index and access rule in the application rather than a data export.
  • No BI tool, ORM or CDC connector speaks FQL, so reporting and analytics always required exporting the data first, and that export tooling is now also unmaintained.
  • The community was small before the shutdown and has dispersed since, so operational answers, tuning advice and people who have run a Fauna cluster in anger are all scarce when something breaks.

Microsoft SQL Server

  • Licensing and on-premises deployment costs are high compared to open-source alternatives, with Enterprise Edition exceeding $60,000 for minimum core requirements
  • Performance monitoring toolset is insufficient for hybrid cloud environments requiring real-time analytics across multiple deployment types
  • Heavy I/O resource consumption can saturate disk volumes and degrade performance when processing large transaction workloads
  • Always On availability groups with up to 8 secondary replicas are limited to Enterprise edition only; Standard supports only basic availability groups with 2 replicas
  • CPU and memory scaling is capped at 4 sockets or 32 cores on Standard edition, limiting deployments requiring higher compute capacity

Pricing, plan by plan

FaunaDB

Free
  • FreeFree
    • 100K read ops
    • 50K write ops
    • 1GB storage
  • Pro$25/month
    • Pay per use
    • Priority support
    • Advanced features

Microsoft SQL Server

Free
  • ExpressFree
    • 4 cores maximum
    • 1.4 GB memory per instance
    • 50 GB database size limit
  • DeveloperFree
    • All Enterprise features
    • Non-production use only
  • Standard$3945/per 2-core pack
    • 32 core maximum per instance
    • 256 GB buffer pool memory
    • Basic availability groups with 2 replicas
  • Enterprise$15123/per 2-core pack
    • Unlimited scaling
    • Always On with up to 8 secondaries
    • Advanced security and HA features

Which should you pick?

Choose FaunaDB if

  • You need document-relational model.
  • You want to start without paying.
  • You also want fql v10.
FaunaDB review

Choose Microsoft SQL Server if

  • You need t-sql.
  • You want to start without paying.
  • You work on Windows Server, Linux (RHEL, SUSE, Ubuntu), Docker, Azure.
  • You also want acid compliance.
Microsoft SQL Server review

Questions people ask

Is FaunaDB or Microsoft SQL Server better?
Neither clearly leads. FaunaDB starts at Free and Microsoft SQL Server at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, FaunaDB or Microsoft SQL Server?
FaunaDB starts at Free and Microsoft SQL Server at Free.
Does FaunaDB or Microsoft SQL Server run on more platforms?
FaunaDB runs on Web. Microsoft SQL Server runs on Windows Server, Linux (RHEL, SUSE, Ubuntu), Docker, Azure.
Can I use FaunaDB for free?
Both have a free tier, so you can try either at no cost before committing.
What is FaunaDB best used for?
FaunaDB is most often used for keeping an existing fauna-backed application alive on self-hosted infrastructure while a migration is planned and funded, extracting historical data from a fauna dataset that can no longer be reached through the hosted api, studying a production implementation of deterministic distributed transactions, since the full server source is now readable under apache 2.0, forking the engine deliberately, where an organisation has jvm and distributed-systems staff and wants a document-relational store it fully controls. Of those, keeping an existing fauna-backed application alive on self-hosted infrastructure while a migration is planned and funded and extracting historical data from a fauna dataset that can no longer be reached through the hosted api are not what Microsoft SQL Server is typically brought in for.
What can FaunaDB do that Microsoft SQL Server cannot?
FaunaDB covers Document-relational model, FQL v10, Distributed ACID transactions, HTTPS access. Microsoft SQL Server covers T-SQL, ACID Compliance, Advanced Security, In-memory OLTP.

Answered from the vendors’ own pages

FaunaDB: Can I still sign up for Fauna as a service?

No. Fauna Inc. wound down the hosted service in 2025 and the company website is no longer serving. The only way to run Fauna now is to build and operate the open-sourced server yourself.

Microsoft SQL Server: What is the pricing model for SQL Server?

SQL Server uses core-based licensing with per-2-core pack pricing. Enterprise Edition costs approximately $15,123 per 2-core pack (minimum 8 cores). Standard Edition costs approximately $3,945 per 2-core pack. Developer and Express editions are free. Software Assurance adds 25-35% annually for upgrades and support.

Source
FaunaDB: What licence is the open-sourced code under?

Apache 2.0, with the copyright held by a FaunaDB Foundation. That is a permissive OSI licence with no competing-use clause, so you may run it, modify it and even offer it as a service.

Microsoft SQL Server: Does SQL Server run on Linux?

Yes. SQL Server 2017 and later run on Linux (Red Hat Enterprise Linux, SUSE Linux Enterprise Server, Ubuntu), Docker containers, and Windows with feature parity including Always On availability groups, Active Directory authentication, and encryption.

Source
FaunaDB: Is the open source version the same software that ran the cloud?

It is the core database engine. The control plane, billing, dashboard and multi-tenant operational tooling that made it a service are not part of the release, so you are running the engine, not the product.

Microsoft SQL Server: Is there a free edition of SQL Server?

Yes. SQL Server Express is free and includes all functionality of Enterprise edition for development and testing, with limits of 4 cores, 1,410 MB memory per instance, and 50 GB per database. Developer edition is also free for non-production use.

Source
FaunaDB: What should I migrate to?

There is no drop-in target. Teams that valued the document model with relationships usually land on Postgres with JSONB, and teams that valued the serverless HTTP access pattern usually land on DynamoDB or a managed Postgres with an HTTP driver. Either way the query layer is rewritten.

Microsoft SQL Server: Can SQL Server be deployed offline?

Yes. SQL Server can be installed from offline media on machines without internet access. Microsoft provides complete offline installation packages for SQL Server, SSMS, and supporting components, making deployment in isolated or air-gapped environments feasible.

Source
FaunaDB: How hard is it to self-host?

It builds as a fat JAR and runs as a multi-node JVM cluster. There is an OPERATING.md, but no supported packaging, no operator, no upstream releases and no support contract, so budget for a distributed-systems engineer, not a container.

Microsoft SQL Server: What high availability options does SQL Server provide?

SQL Server offers Always On availability groups (Enterprise only), Always On failover cluster instances, database mirroring, log shipping, and for disaster recovery, failover servers in Azure and Accelerated Database Recovery for faster recovery after failures.

Source
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