Should I migrate from SQL Server to MySQL or PostgreSQL?

Postgres is usually the better Microsoft → open-source migration target because of stronger procedural-code portability (PL/pgSQL handles T-SQL patterns more naturally than MySQL's stored routines). MySQL wins when: (a) your application stack is already MySQL-fluent, (b) you want MySQL HeatWave for analytics consolidation, (c) workload is thin on T-SQL and you prefer MySQL's simpler operational model. See PostgreSQL vs SQL Server for the more common migration framing.

T-SQL → MySQL stored routines — how big is the rewrite?

Bigger than T-SQL → PL/pgSQL. MySQL stored routines are simpler than T-SQL: no CTEs in older versions (8.0+ supports them), simpler exception handling, no XML/JSON-heavy stored procedure features, no CLR integration. For applications with significant T-SQL surface (especially SSIS / SSRS / SSAS integrations), Postgres is the more natural target. For thin T-SQL applications, MySQL works fine but the rewrite scope needs honest audit.

Always On Availability Groups vs MySQL HA?

Always On AG provides synchronous + asynchronous replicas across data centres with automatic failover, deeply integrated with Windows Failover Clustering. MySQL equivalents: InnoDB Cluster (Group Replication-based, single-primary by default, multi-primary available), Galera Cluster via Percona XtraDB Cluster or MariaDB Galera (mature synchronous multi-master), Orchestrator for failover automation. Always On AG is more polished operationally; MySQL HA is leaner and lower-cost. For Always-On-equivalent semantics on MySQL, InnoDB Cluster + ProxySQL is the closest pattern.

SQL Server Enterprise: ~$14,000 per 2-core pack + Software Assurance, typically 6-figure annual cost. MySQL Enterprise (Oracle-licensed): ~$5,000-10,000 per server-year (much cheaper). MySQL Community: GPL, $0 licence + paid support tier if needed ($50k-200k/year for enterprise support). At enterprise scale (100+ cores across non-prod/prod), savings are typically $200k-$1M+/year — usually paying back migration cost within 12-24 months.

Aurora MySQL vs RDS MySQL for SQL Server migration target?

Aurora MySQL gives cluster-storage performance + 15 read replicas + Global Database — best for read-heavy SQL Server workloads being modernised. RDS MySQL is cheaper at smaller scale and provides standard managed MySQL. Both are viable; the choice depends on workload scale. See Aurora MySQL services and RDS MySQL services for the cloud-managed landing.

Sound familiar?

▸ SQL Server licensing renewal — finance asking whether MySQL can replace SQL Server in 90-180 days; T-SQL surface audit hasn't happened.
▸ Always On replacement — InnoDB Cluster or Galera, but the operational tradeoffs need a defensible architecture call.
▸ Aurora MySQL evaluation as the SQL Server replacement target — cluster-storage + 15 read replicas are appealing, but T-SQL rewrite scope dominates the migration cost.

JusDB consultants build the MySQL-vs-SQL-Server migration decision with the T-SQL audit attached. Book a migration scoping call →

MySQL vs SQL Server

Short answer: Choose MySQL when your stack is already MySQL-fluent, T-SQL surface is thin, zero licensing cost matters at scale, or you want HeatWave analytics consolidation; choose SQL Server for T-SQL-heavy stacks with SSIS/SSRS/SSAS, Always On Availability Groups, native columnstore, CLR procedures, or an Azure-native estate. For deep T-SQL migrations off Microsoft, PostgreSQL is usually the more natural target than MySQL.

Open-source flagship vs Microsoft's commercial RDBMS. Licensing math, T-SQL portability, Always On vs InnoDB Cluster — the production-DBA view of when migration pays off.

Feature matrix

Dimension	MySQL 8+	SQL Server 2022
Licence	GPLv2 (Community) + Commercial (Enterprise)	Commercial — Enterprise / Standard / Developer / Express
Procedural language	Stored routines (no packages, simpler than T-SQL)	T-SQL + CLR integration (C#) for advanced procedures
HA	InnoDB Cluster + Galera Cluster + Orchestrator	Always On Availability Groups + Failover Clustering
Columnstore / analytics	MySQL HeatWave (OCI only) for in-memory analytics	Clustered + nonclustered columnstore indexes native
JSON	JSON type + multi-valued indexes	JSON via text + JSON_VALUE / JSON_QUERY functions
Platform support	Linux, Windows, macOS — all production-equal	Windows + Linux (containers + native); macOS dev only
Cloud-managed	RDS MySQL, Aurora MySQL, Cloud SQL, Azure Flexible Server, HeatWave	Azure SQL DB, Azure SQL MI, RDS SQL Server, Cloud SQL for SQL Server
Migration tooling	AWS SCT + DMS, MySQL Workbench Migration Wizard, sqlines	SQL Server Migration Assistant (SSMA), Azure DMS

When MySQL wins

Team is MySQL-fluent already with Aurora / RDS MySQL stack ergonomics.
Zero licensing cost matters at scale.
Cloud strategy prefers AWS / GCP — broader MySQL managed-service ecosystem.
HeatWave analytics consolidation on OCI is the strategic anchor.
Open-source procurement / vendor-neutral stack is a requirement.
Thin T-SQL surface — most logic can be moved to application tier.

When SQL Server wins

T-SQL-heavy stack with SSIS / SSRS / SSAS investments.
Always On AG + Windows Failover Clustering is mission-critical.
Mixed OLTP + analytical workload on one engine (columnstore is genuinely capable).
Microsoft Enterprise Agreement makes licensing math irrelevant.
Azure-native stack with deep SQL Server / Azure SQL DB integration.
CLR integration (C# stored procs) is part of the application architecture.

Common questions

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