As this re-engineering is such a mammoth task, not all features of the SQLOS and SQLPAL are combined. This means that, for SQL Server 2017, there is a list of features in SQL Server that are not supported. The clear plan at Microsoft is to make sure that these features are introduced into future releases of SQL Server, with the ultimate goal of feature parity between SQL Server running on both operating systems:

• Database Engine:
  • Transactional replication
  • Merge replication
  • Stretch DB
  • Polybase
  • Distributed query with third-party connections
  • System extended stored procedures (XP_CMDSHELL, and so on)
  • Filetable, FILESTREAM
  • CLR assemblies with the EXTERNAL_ACCESS or UNSAFE permission set
  • Buffer Pool Extension
• High availability:
  • Database mirroring
• SQL Server Agent:
  • Subsystems: CmdExec, PowerShell, Queue Reader, SSIS, SSAS, and SSRS
  • Alerts
  • Log Reader Agent
  • Change Data Capture
  • Managed Backup
• Security:
  • Extensible Key Management
  • AD Authentication for Linked Servers
  • AD Authentication for Availability Groups (AGs)
  • Third party AD tools (Centrify, Vintela, and Powerbroker)
• Services:
  • SQL Server Browser
  • SQL Server R services
  • StreamInsight
  • Analysis Services
  • Reporting Services
  • Data Quality Services
  • Master Data Services
  • Distributed Transaction Coordinator (DTC)

This list is, of course, rather long and includes some important candidates that may cause SQL Server on Linux to be a non-starter for many in its current incarnation. However, the list doesn't include some first-class features, such as In-Memory OLTP or Availability Groups, meaning that these features are supported with SQL Server on Linux.

As with recent releases of SQL Server, we can also expect that these, currently missing, features will quickly be included in the product so that a current show-stopper for a SQL Server on Linux deployment can expect to be removed from the missing-feature list in the foreseeable future.