PostgreSQL is a powerful, open source object-relational database system that provides unlimited database size. Thingworx 6.5 introduces PostgreSQL as persistence provider and supports High Availability. Main advantages with Thingworx Postgres are
1. Highly customizable
PostgreSQL also includes a framework that allows developers to define and create their own custom data types along with supporting functions and operators that define their behavior. Triggers and stored procedures can be written in C and loaded into the database as a library, allowing great flexibility in extending its capabilities.
2. Synchronous replication
PostgreSQL streaming replication is asynchronous by default. Synchronous replication offers the ability to confirm that all changes made by a transaction have been transferred to one synchronous standby server. This extends the standard level of durability offered by a transaction commit. The only possibility that data can be lost is if both the primary and the standby suffer crashes at the same time.
3. Write ahead logging for fault tolerance
The Write Ahead Log (WAL), is the feature of PostgreSQL that allows it to recover data, usually up to the point where the server stopped. As you make changes to your data, PostgreSQL aggressively writes those changes to the WAL. PostgreSQL issues a checkpoint when a buffer limit is reached. When PostgreSQL restarts, it replays the changes from the WAL since the last Checkpoint, to bring the database back to the state of the last completed commit. Master node sends a live stream of data changes to the slave nodes through the WAL and slaves applies this data and stay up to date.
4. Point-in time recovery
Point-in-time Recovery (PITR) also called as incremental database backup , online backup or may be archive backup. This mechanism use the history records stored in WAL file to do roll-forward changes made since last database full backup. With Point-in-time Recovery, database backup down time can totally eliminated because this mechanism can make database backup and system access happened at the same time. with PITR, we backup the latest archive log file since last backup instead of full database backup everyday.
Thingworx streams data from the connected devices and postgres handles it with a greater scalability. In Thingworx, postgresql acts as a persistence provider that stores both run-time data and metadata about things. Run-time data is the data that is persisted once the things are composed and are used by connected devices to store their data. Streams and value streams fetch huge amounts of data, once the streaming data reaches a limit fo 50gb neo4j can't handle the performance. For example, for a singleStream that has 50 properties that gathers data from 10000 devices, it will quickly hit the memory limit with neo persistence provider. So, it is strongly recommended to choose postgresql for a better performance issues.
Overview of Installing Thingworx PostgreSQL:
- Install latest version of Java and make sure environment variables are configured.
- Follow the instructions in Installing Thingworx 6.5 to install tomcat. Instructions/commands may vary for different Linux flavors.
- Install PostgreSQL. For Linux/Unix environments, YUM-Installation Guidelines.
- Create 'ThingworxPostgresqlStorage' and 'ThingworxPlatform' folders in the root directory( / ), assign access permissions to the user.
- Copy modelproviderconfig.json file (from Thingworx download package) to 'ThingworxPlatform' folder.
- Execute ThingworxPostgresSchemaSetup and ThingworxPostgresDBSetup scripts (.bat for windows and .sh for Unix/Linux environments), for further instructions follow Getting Started with PostgreSQL ThingWorx Administrators Guide.
- Restart the tomcat.