This is an interesting topic. When people think of database elements, they generally think of ASCII or digital data that can be readily indexed in a database. But in the case of biometric security measures, data like fingerprints, facial recognition data, retinal scan information, etc. are the elements stored. This data, like image data, is hard to develop efficient search engine attributes for; you don't want your applications doing sequential searches.
Of course the first answer is: "What does your biometric vendor recommend?" But if your company is developing its own application or starting the process of looking at this product area, you may not have a vendor's expertise to rely on. The good news is that there is research being conducted on biometric data efficiency. In this case, I will defer to the experts and point you to a study headed by Amit Mhatre, a software developer for Amazon, "Efficient Search and Retrieval in Biometric Databases." This research is comprehensive and should answer any questions you have around efficiently storing this personal physical information.
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This was first published in February 2010