Applications that pin history (even relatively small amounts), by having long running transactions or keeping timestamps pinned. Workloads that have hot keys, can end up with long update chains.

We should investigate how to more efficiently handle long update chains when history is pinned. Avenues worth exploring are:

• Ensure that update-restore eviction is worthwhile, before paying the cost of reconciliation.
• Avoid continually re-writing content to the lookaside file, for large pages that are being regularly updated.
• Ensure update chains are trimmed when possible.

This work is related to WT-3755, but differs because it's focused on cases where some history is pinned.