Key areas where a VLDB may present challenges include configuration, storage, performance, maintenance, administration, availability and server resources.
Configuration Careful configuration of databases that lie in the VLDB realm is necessary to alleviate or reduce issues raised by VLDB databases.
Administration The complexities of managing a VLDB can increase exponentially for the
database administrator as database size increases.
Availability and maintenance When dealing with VLDB operations relating to maintenance and recovery such as database reorganizations and file copies which were quite practical on a non-VLDB take very significant amounts of time and resources for a VLDB database. In particular it typically infeasible to meet a typical
recovery time objective (RTO), the maximum expected time a database is expected to be unavailable due to interruption, by methods which involve copying files from disk or other storage archives. To overcome these issues techniques such as clustering, cloned/replicated/standby databases, file-snapshots, storage snapshots or a backup manager may help achieve the RTO and availability, although individual methods may have limitations, caveats, license, and infrastructure requirements while some may risk data loss and not meet the recovery point objective (RPO). For many systems only geographically remote solutions may be acceptable.
Backup and recovery Best practice is for backup and recovery to be architectured in terms of the overall availability and business continuity solution.
Performance Given the same infrastructure there may typically be a decrease in performance, that is increase in
response time as database size increases. Some accesses will simply have more data to process (scan) which will take proportionally longer (
linear time); while the indexes used to access data may grow slightly in height requiring perhaps an extra storage access to reach the data (
sub-linear time). Other effects can be
caching becoming less efficient because proportionally less data can be cached and while some
indexes such as the
B+ automatically sustain well with growth others such as a
hash table may need to be rebuilt. Should an increase in database size cause the number of accessors of the database to increase then more server and network resources may be consumed, and the risk of
contention will increase. Some solutions to regaining performance include
partitioning,
clustering, possibly with
sharding, or use of a
database machine.
Partitioning Partitioning may be able assist the performance of bulk operations on a VLDB including backup and recovery., bulk movements due to
information lifecycle management (ILM), reducing contention as well as allowing optimization of some query processing.
Storage In order to satisfy needs of a VLDB the database
storage needs to have low access
latency and
contention, high
throughput, and
high availability.
Server resources The increasing size of a VLDB may put pressure on server and network resources and a bottleneck may appear that may require infrastructure investment to resolve. ==Relationship to big data==