A question that many customers have asked me is whether TimesTen is just a cache for their Oracle database or an (RDBMS) system of record. TimesTen can be configured to be either a read/write cache for Oracle databases, or act as a system of record.
TimesTen is a low latency In-Memory RDBMS which persists data to disk and supports ACID transactions.
The checkpoint files and transaction logs persist the data to enable database recovery in the unlikely event of hardware or software failure. TimesTen uses the transaction logs files to support persistent ACID transactions with COMMIT and ROLLBACK operations. TimesTen also supports many replication configurations to enable high availability and online upgrades.
TimesTen uses SQL and PLSQL and supports many runtime environments:
TimesTen In-Memory Database is a transactional, recoverable, RDBMS for SQL and PLSQL applications which acts as a system of record for most of our customers.
Tables in the TimesTen In-Memory RDBMS can be configured to act as read only or read/write caches for the corresponding tables in an Oracle database. When TimesTen is caching tables from Oracle, the data is still persistent and recoverable. Both cached and non-cache [local] tables can exist in a TimesTen database at the same time. Applications can do SQL joins between cache and non cache tables :
Applications that connect to the TimesTen (cache) tables benefit from the lower latency that TimesTen provides. Using TimesTen Application Tier Cache with for Oracle 12c Exadata gives you the best of both - low latency from TimesTen and massive scalability from Exadata. This white paper gives more details on TimesTen Caching.
This Telecommunications benchmark (TATP HLR) shows dramatic reductions in response times when the Oracle Database uses TimesTen Application Tier Database Cache. This benchmark is an apples to apple comparison:
In summary, TimesTen can be configured as either a system of record or as a Read/Write Cache for Oracle 11g/12c.
Disclaimer: these are my personal thoughts and do not represent Oracle's official viewpoint in any way, shape, or form.