Bulk UPDATE and DELETE: statement, key loop, record-API loop, or UPSERT loop #360

Problem

I want to know which bulk update and delete shape is cheapest, how the cost grows with N, and where the share sweep changes the answer.

It is one row of the bindings study list. It was held on stale pins and re-pins after the 26.11.1 release wheels exist.

Priority: P3 (not on any deadline).

Acceptance

• The dry run is clean and its report is written
• The study runs and is scored
• The docs recommend one shape per case with its figure

Results and the scorer output go in this issue as comments. Numbers are generated by script from the result files, never typed.