Interview Question of the Week #026 – 64 Bit Vs 32 Bit Confusion

I often see people get tangled up in the words 32 bit and 64 bit. Are we talking about Windows, the SQL Server database engine, or the client program? The answer changes with that one detail.

Question: Which combinations of 32 bit and 64 bit Windows and SQL Server can run together?

Answer: Here is the simple matrix from my original interview question. It describes SQL Server releases that offered both 32 bit and 64 bit engines, on compatible Windows versions. It is a historical compatibility explanation, not installation advice for today’s releases.

The second row is the one to remember: a 32 bit operating system cannot host a 64 bit database engine. The third row surprises some candidates because older 32 bit SQL Server builds could run on a supported 64 bit Windows installation. You still have to check the particular SQL Server and Windows support matrix.

What changed? SQL Server 2014 was the last major release with a 32 bit database engine. SQL Server 2016 and later use a 64 bit database engine. You should not go looking for a modern 32 bit engine installer because an old interview matrix says the combination was once possible.

A client program is a separate question. A 32 bit application can connect over the network to a 64 bit SQL Server engine. A driver or provider loaded inside that client process must be compatible with the client’s architecture. This is often the real source of today’s 32 bit versus 64 bit confusion.

If you are unsure which engine answered your query, ask that engine directly:

SELECT @@VERSION AS VersionDescription,
       SERVERPROPERTY('ProductVersion') AS ProductVersion,
       SERVERPROPERTY('Edition') AS Edition;

Look at the connected server’s version description, not merely the bitness of SSMS on your laptop. That is the short answer I hope a candidate can explain before reaching for a long troubleshooting checklist.

Published by Pinal Dave on SQLAuthority. More of my work at pinaldave.com.