Query Interface

SQL

Views

Materialized Views

Concurrency Control

Multi-version Concurrency Control (MVCC) Two-Phase Locking (Deadlock Detection)

Concurrency control of TimesTen is achieved through isolation and locking. It supports fully ACID transactions but allow user to loose it for performance by modifying configuration.

Locking

TimesTen provides three level of lock granularity: row-level, table-level and database-level. By default, row-level locking is used to maximize the throughput. TimesTen has lockless multi-versioning mechanism for read-write concurrency and uses row-level locking to ensure write-write concurrency.

Deadlock Detection

Deadlock detection is supported in TimesTen with a subdaemon process checking every 2 seconds. It reports and eliminates deadlock when the situation occurs. Application should roll back and retry entire transaction when it is denied a lock due to deadlock error.

Isolation Levels

Read Committed Serializable

Stored Procedures

Supported

Indexes

B+Tree Hash Table BitMap T-Tree

By default TimesTen uses B+Tree. The original version (SmallBase) from the 1990s supported T-Trees. TimesTen still supports T-Tree indexes but the administrator has to request for the DBMS to use them.

Storage Architecture

In-Memory

Checkpoints

Non-Blocking Blocking Fuzzy

TimesTen maintains two checkpoint files (ds0 and ds1) on disk to keep track of metadata of in-memory permanent data. It switches two files when a checkpoint is done to ensure there is always at least one completed checkpoint file for backup and recovery purpose. The rate for checkpointing disk writes is configurable by application. It supports fuzzy or non-blocking checkpoints as well as transaction-consistent checkpoints (i.e. blocking checkpoints).

Data Model

Relational

System Architecture

Shared-Nothing

Compression

Dictionary Encoding

TimesTen supports columnar compression. This feature uses dictionary-based encoding to replace column values with dictionary table identifiers. It maintains separate dictionary for each column.