VDO 512 byte block size emulation

I have a database manager which requires a 512 byte block size. I was receiving a I/O error when using the VDO native 4096 byte block size. My question is, are there any performance hits from using the "--emulate512" argument when creating VDO devices.

I found this:
https://access.redhat.com/solutions/3357571

I'd also like to understand this statement a little clearer:
"The 512 byte emulation mode uses read-modify-write to update 4K physical blocks with sub-4K write IO. "

Does this mean there is an additional layer sitting between the application and the VDO device performing the emulation?