Store partition ids as partition keys to reduce obj creation. #3477

All 51 tests pass in 27s

8 files + 8 8 suites +8 27s ⏱️ +27s
51 tests + 51 51 ✅ + 51 0 💤 ±0 0 ❌ ±0
175 runs +175 175 ✅ +175 0 💤 ±0 0 ❌ ±0

Results for commit 607db71. ± Comparison against earlier commit d2f4a17.