It is either essential or highly recommendable, to insert the following file extensions as exceptions to antimalware products, most especially on servers.

Exchange & Windows Search Indexing:

*.edb
*.stm

Microsoft SQL server and others:

*.mdf
*.ldf

StorageCraft:

*.spf
*.spi
*.spk

BlackBerry Enterprise Server:

*.pdb

Microsoft virtual machine:

*.vhd

QuickBooks:

*.DES
*.IIF
*.ND
*.QBA
*.TLG
*.QBB
*.QBM
*.QBR
*.QBW
*.QBX
*.QBY

Quicken:

*.QDF
*.QEL
*.QPH
*.IDX
*.QSD
*.QDB

AutoCAD Inventor:

*.ipt
*.iam
*.idw
*.dwg
*.ipn
*.ide
*.prt
*.g
*.asm
*.neu
*.dxf

Borland Paradox, Pervasive SQL, AutoCAD, and others:

*.db
*.sdf
*.ddf
*.mkd
*.pvsw

For Pervasive databases, in addition to the above, you can load the Monitor to see files and folders in use.

For Oracle databases, see here:

http://www.orafaq.com/wiki/File_extensions

All the extensions above, in one swell foop:

*.edb
*.stm
*.mdf
*.ldf
*.spf
*.spi
*.spk
*.pdb
*.vhd
*.DES
*.IIF
*.ND
*.QBA
*.TLG
*.QBB
*.QBM
*.QBR
*.QBW
*.QBX
*.QBY
*.QDF
*.QEL
*.QPH
*.IDX
*.QSD
*.QDB
*.db
*.sdf
*.ddf
*.mkd
*.ipt
*.iam
*.idw
*.dwg
*.ipn
*.ide
*.prt
*.g
*.asm
*.neu
*.dxf