Problem Statement: Problem Statement

Detection

• The best way to detect if the logical log is a bottleneck is to look at the recent checkpoint activity:
• The server keeps track of the last 20 checkpoints.
• If a substantial portion of the recent checkpoints were triggered because of the logical log, then we should increase the logical log space by adding another logical log.
• If a long transaction or checkpoint blocking occurs because of the logical log, we should also add another logical log to the log space.

Expansion

• Expansion

• We already have the adding logical logs dynamically feature:
• DYNAMIC_LOGS 2 in the configuration file defined by $ONCONFIG environment variable.
• Typically executes only when the server runs out of logical log space.
• The server already contains the logic to extend a dbspace while adding a logical log.
• There is a new, additional Logical Log expansion parameter in the configuration file called AUTO_LLOG
• Enables the automatic addition of logical logs when the database server detects that adding logical logs improves performance.
• If enabled, log expansion occurs:
• When 5 of the last 20 checkpoints were caused by logical logs filling up
• When a logical log causes a blocking checkpoint
• When a logical log causes a long checkpoint
• AUTO_LLOG & DYNAMIC_LOGS do not interact