Document automatic log-switch setting for low-frequency change systems

In some cases, users connect to a very low-frequency changing Oracle database and the LogMiner session may not get restarted frequently enough leading to PGA_AGGREGATE_LIMIT failures.

This can be remedied by configuring Oracle to automatically perform a log switch on an interval if one hasn't occurred, see below. This triggers a log switch every 20 minutes.

alter system set archive_lag_target=1200 scope=both;