Autonomous Data Warehouse provides three sets of database services to use when connecting to your dedicated database. In each set, one service provides a secure TCP (TCPS) connection using the TLS protocol, and another provides a TCP connection. And then, for databases configured to use Autonomous Data Guard, two more service provide these same kinds of connections (TCPS and TCP) to the standby database for read-only access.
These three sets of connection services are designed to support different kinds of database operations:
- high_tls, high, high_ro_tls and high_ro: For high priority reporting and batch operations.
- medium_tls, medium, medium_ro_tls and medium_ro: For typical reporting and batch operations.
- low_tls, low, low_ro_tls and low_ro: For low priority reporting and batch operations.
The following table compares these characteristics of these three sets of database services:
Degree of Parallelism: Parallel execution is a feature of Oracle Autonomous Database that creates and uses multiple processes to execute a single SQL statement. The degree of parallelism specifies the number of processes that can be used. Due to the performance cost of creating additional processes, parallel execution is generally worthwhile when:
- The query references a large data set.
- There is low concurrency.
- Elapsed time is important.
Resource Shares: Oracle Autonomous Database uses Oracle Database Resource Manager consumer groups to provide different resource allocations to each pair of database services. Resources shares define the guaranteed fraction of resources a consumer group will be granted. However, any consumer group can use more than the guaranteed amount of a resource when no resource contention exists.
Concurrent Statements: The maximum number of SQL statements that the database can be processing for a consumer group before statements are queued.
FAN Enabled: Whether Fast Application Notification is enabled by default.
TAC Enabled: Whether Transparent Application Continuity is enabled by default.
|Service Names||Degree of Parallelism||Resource Shares||Concurrent Statements||FAN Enabled||TAC Enabled|
|high_tls, high, high_ro_tls and high_ro||OCPUs||4||3||Yes||No|
|medium_tls, medium, medium_ro_tls and medium_ro||4||2||1.25 × OCPUs||Yes||No|
|low_tls, low, low_ro_tls and low_ro||1||1||300 × OCPUs||Yes||No|
The number of OCPUs is the CPU Core Count shown in the Oracle Cloud console.
Note:After connecting to the database using one service, do not attempt to manually switch that connection to a different service by simply changing the consumer group of the connection. When you connect using a service, Autonomous Data Warehouse performs more actions to configure the connection than just setting its consumer group.