We're starting a new project from scratch with ArcGIS Server 10.3.1.
Provided that the hardware is exactly the same (Memory, processors, etc), has anyone compared the performance of Enterprise geodatabase running on Postgresql 9.x versus Microsoft SQL Server 2012/2014 ?
What about any performance comparison between Postgresql/Postgis without SDE, versus ESRI Geodatabase in Postgres.
Thanks in advance for your feedback.
The question you ask is very broad, really too broad for people to provide meaningful feedback. For example, stating "that the hardware is exactly the same (Memory, processors, etc)" but not providing any of the specs makes it impossible for someone to comment on how SQL Server or PostgreSQL will perform on that hardware, let alone compare the two DBMSes. Even if there were some general/generic performance statements that could be made about the two systems, performance is just one of many factors or business requirements that play into deciding between platforms.
Regarding your second question about PostgreSQL with and without SDE, I would say it also depends on your requirements. Esri's SDE/geodatabase technology offers some advanced data models that don't exist natively in DBMSes, and it is the native data storage for ArcGIS software, but cutting out middleware usually helps performance if you don't actually need it.
The more specifics you can provide about your situation and requirements, the more likely people will be able to provide feedback.