Predefined Database Service Names for Autonomous Data Warehouse

The tnsnames.ora file provided with the credentials zip file contains three database service names identifiable as high, medium, and low. The predefined service names provide different levels of performance and concurrency for Autonomous Data Warehouse.

  • high: The High database service provides the highest level of resources to each SQL statement resulting in the highest performance, but supports the fewest number of concurrent SQL statements. Any SQL statement in this service can use all the CPU and IO resources in your database. The number of concurrent SQL statements that can be run in this service is 3, this number is independent of the number of OCPUs in your database.

  • medium: The Medium database service provides a lower level of resources to each SQL statement potentially resulting a lower level of performance, but supports more concurrent SQL statements. Any SQL statement in this service can use multiple CPU and IO resources in your database. The number of concurrent SQL statements that can be run in this service depends on the number of OCPUs in your database.

  • low: The Low database service provides the least level of resources to each SQL statement, but supports the most number of concurrent SQL statements. Any SQL statement in this service can use a single CPU and multiple IO resources in your database. The number of concurrent SQL statements that can be run in this service can be up to 100 times the number of OCPUs.

Sessions in these services may get disconnected if they stay idle for more than five (5) minutes and other users' sessions require the resources consumed by the idle session. This allows resources to be freed for other active users in your database.

The following shows the details for the number of concurrent statements for each connection service.

Database Service Name Concurrent Statements

high

3

medium

1.25 × OCPUs

low

100 × OCPUs

The number of OCPUs is the CPU Core Count shown in the Oracle Cloud console.

The following table shows sample values for a database with 16 OCPUs.

Database Service Name Number of Concurrent Queries

high

3

medium

20

low

Up to 100 times the number of OCPUs

Choose whichever database service offers the best balance of performance and concurrency.

Note:

When connecting for replication purposes, use the low database service name. For example use this service with Oracle GoldenGate connections.