A. 6000 companies, 1,320,000 rows: delete + insert each company
   one transaction for all companies, no lock                  14.0s
   one transaction per company, no lock                        21.6s
   one transaction per company + xact lock                     21.8s
   50 companies per transaction + xact locks, sorted           15.8s
   one transaction per company + xact lock, 4 workers           6.1s
   one transaction per company + xact lock, 8 workers           3.5s

B. 8 concurrent SERIALIZABLE rebuilds of 8 DIFFERENT companies, no lock (every failure is a false conflict)
   no index, adjacent ids               failed: 7 of 8
   index, adjacent ids                  failed: 6 of 8
   index, ids spread across the table   failed: 0 of 8

C. 8 workers each rebuild the same 10 companies (overlapping runs), 0.3 s of work each
   SERIALIZABLE + retry, no lock      8.8s, failed attempts 101, rows 2200 (expected 2200)
   READ COMMITTED + xact lock         5.4s, failed attempts   0, rows 2200 (expected 2200)