SQL Server 2025

SQL Server 2025 Express is free and permits production use within its limits: 50 GB per relational database, the lesser of one socket or four cores, and 1,410 MB of buffer pool memory. Standard supports the lesser of four sockets or 32 cores and 256 GB of buffer pool memory, with per-core or Server + CAL licensing. Enterprise scale is subject to operating-system and feature-specific limits. Enterprise Developer and Standard Developer are free development and test editions, not production licences. Compare the official SQL Server 2025 edition matrix rather than carrying forward SQL Server 2022 limits.

On bare metal you license every physical core on the host, sold in 2-core packs, with a minimum of 4 cores per processor. Hyperthreading does not change the count: a 32-thread, 16-physical-core CPU still needs 16 core licences. For VMs, the rule is per-vCPU with a 4-core minimum per VM, regardless of host core count. The economical pattern for highly virtualised SQL fleets is to license every physical core on the host with Enterprise + Software Assurance and run unlimited SQL Server VMs on that host; for a one-off SQL VM, licensing only the vCPUs allocated to that VM is cheaper. Software Assurance is strongly recommended for any non-trivial deployment — it is mandatory for License Mobility (running the same licence on Azure or another cloud), for version upgrade rights, and for the failover-rights entitlement on passive secondaries.

Standard can also be bought as a Server licence plus per-user or per-device CALs. This model is generally a win when the audience is small and well-defined (under roughly 25 named users), where per-core maths is unfavourable. Typical fits: an internal departmental database, a back-office line-of-business application with a known headcount, or a SQL Reporting Services instance whose audience is a small business intelligence team. Above 25 users, per-core almost always wins because CAL costs scale linearly with the audience while per-core does not.

Standard supports two-node basic Always On with a single secondary, intended for simple failover within a single rack or data centre. Enterprise supports up to eight secondaries with read-scale routing, multi-subnet failover, and asynchronous geo-secondaries. SQL Server 2022 introduced contained availability groups that ship system databases (master, msdb) along with the AG so that linked servers, jobs and logins follow failover cleanly; 2025 builds on that with smoother cluster-less topologies. For DR, the Managed Instance link feature replicates an on-prem SQL Server to a managed Azure instance with low RPO — useful for staged cloud migrations and warm-standby DR without standing up a second on-prem cluster.

Qualifying SQL Server subscriptions or licences with active Software Assurance can include passive failover rights subject to Microsoft Product Terms. A passive replica must not serve application data or active reporting workloads. Certain maintenance activities, including consistency checks and backups, can be permitted by the applicable rights; they do not automatically make every replica an active licensed workload. Document HA and disaster-recovery topology, location and permitted activities against the current agreement.

SQL Server 2025 introduces native vector data types, the VECTOR_DISTANCE function with cosine, dot-product and Euclidean metrics, and T-SQL syntax for calling Azure OpenAI or local model endpoints directly from a stored procedure. This brings retrieval-augmented generation patterns inside the database without an external embedding service. JSON is now a binary on-disk type rather than a constrained NVARCHAR, with faster path queries and smaller storage. The Managed Instance link, Synapse Link for near-real-time analytics into a serverless SQL pool, and Microsoft Fabric mirroring all continue to evolve — these features assume an Azure subscription on the other end but they make the on-prem engine a much better citizen of a hybrid data estate.

SQL Server 2025 continues to ship on Linux (Red Hat Enterprise Linux, Ubuntu, SUSE) with the same engine binary as the Windows build, and as an official container image for production use. The licensing is identical to the bare-metal install — license the host's cores. The container image is the supported path for CI/CD pipelines, ephemeral test environments and Kubernetes-based deployments via the SQL Server operator. For local development, SQL Server Developer Edition on Windows or Linux remains free and feature-complete; Azure SQL Edge has been deprecated in favour of running the full engine on smaller hardware.