Databases Reference
In-Depth Information
or phrase? Can you rank search results according to how closely a record
matches your keyword search? This topic was covered in chapter 7.
Agility
—How quickly can the software be modified to meet changing business
requirements? We prefer the term agility over
modifiability
, since agility is associ-
ated more closely with a business objective, but we've seen both terms in use.
This topic was covered in chapter 9.
Beware of vendor-funded performance benchmarks
and claims of high availability
Several years ago, one of us was working on a database selection project when a
team member produced a report which claimed that vendor A had a tenfold perfor-
mance advantage over the other vendors. It took our team several days of research
to find that the benchmark was created by an “independent” company that was paid
by vendor A. This so-called independent company selected samples and tuned the
configuration of the funding vendor to be optimized. No other databases were tuned
for the benchmark. Most external database performance benchmarks are targeting
generic read, write, or search metrics. They won't be tuned to the needs of a specific
project and as such aren't useful for making valid comparisons.
We avoid using external benchmarks in comparing performance. If you're going to do
performance bake-offs, you must make sure that each database is configured appro-
priately and that experts from each vendor are given ample time to tune both the hard-
ware and software to your workload. Make sure the performance benchmark will
precisely match the data types you'll use and use your predicted peak loads for
reads, writes, updates, and deletes. Also make sure that your benchmark includes
repeated read queries so that the impact of caching can be accounted for.
Vendor claims of high availability should also be backed up by visits to other custom-
ers' sites that can document service levels. If something sounds too good to be true,
it probably is. Any vendor with astounding claims should back up the claims with
astounding evidence.
12.4.2
Evaluating hybrid and cloud architectures
It's usually the case that no single database product will meet all the needs of your
application. Even full NoSQL solutions that leverage other tools such as search and
indexing libraries may have gaps in functionality. For items like image management
and read-mostly
BLOB
storage, you might want to blend a key-value store with another
database. This frequently requires the architectural assessment team to carefully parti-
tion the business problem into areas of concern that need to be grouped together.
One of the major themes of this topic has been the role of simple, modular, data-
base components that can snap together like Lego blocks. This modular architecture
makes it easier to customize service levels for specific parts of your application. But
it also makes it difficult to do an apples-to-apples comparison. Running a single
