Changes in This Release for Oracle Universal Connection Pool Developer's Guide

This preface contains:

The following are changes in Oracle Universal Connection Pool Developer's Guide for Oracle Database 12c Release 2 (12.2.0.1).

The following features are new in this release:

Shared Pool Support for Sharded Databases

See "Shared Pool for Sharded Databases"
Shared Pool Support for Multitenant Data Sources

See "Shared Pool Support for Multitenant Data Sources"
Switch Service Enhancement

Starting from Oracle Database 12c Release 2 (12.2.0.1), you can use the SET CONTAINER statement in the following way, if you want to switch among pluggable databases, while continuing to use user services with full service functionality:
```
ALTER SESSION SET CONTAINER=<container name> SERVICE=<service name>;
```
Support for setting connection validation frequency

See "Minimizing Connection Request Delay"
Support for feature-specific logging at runtime

"Enabling or Disabling Feature-Specific Logging at Runtime"
Real-World Performance Enhancement

See "About Optimizing Real-World Performance with Static Connection Pools"