Say that prefetching items did not pay, and why (109)

Fetching a found item's cells, a leaf's keys and each level's keys ahead
made finding and reading items 20% faster on 100,000 items in a micro
benchmark, but TPC-C's clean pairs moved 1% at most and finding alone got
48% slower, so it is not in. The owner's finding samples were the descent,
not the fields: a write right after a read copies the leaf whole anyway,
and what costs is walking structures larger than the caches at random.

17 files changed, 201 insertions, 0 deletions

diff --git a/research/experiments/024-finding-items/2026-09-30-micro-linux-aarch64.txt b/research/experiments/024-finding-items/2026-09-30-micro-linux-aarch64.txt
new file mode 100644
index 0000000..df7d999
--- /dev/null
+++ b/research/experiments/024-finding-items/2026-09-30-micro-linux-aarch64.txt
@@ -0,0 +1,6 @@
+load average at the start: (3.32470703125, 3.7529296875, 3.55712890625)
+ 100000 before seek: 125.4 ns (x1.69)  seek+3 reads: 339.3 ns (x1.36)  seek+3 reads+3 changes: 433.7 ns (x1.33)  same, a share each 30: 681.5 ns (x1.15)
+ 100000 after  seek: 185.9 ns (x1.10)  seek+3 reads: 270.8 ns (x1.08)  seek+3 reads+3 changes: 360.1 ns (x1.07)  same, a share each 30: 597.2 ns (x1.12)
+ 400000 before seek: 212.6 ns (x1.10)  seek+3 reads: 384.7 ns (x1.02)  seek+3 reads+3 changes: 505.4 ns (x1.12)  same, a share each 30: 855.1 ns (x1.22)
+ 400000 after  seek: 261.8 ns (x1.55)  seek+3 reads: 348.8 ns (x1.63)  seek+3 reads+3 changes: 470.6 ns (x1.18)  same, a share each 30: 801.6 ns (x1.51)
+load average at the end: (3.677734375, 3.7158203125, 3.5546875)
diff --git a/research/experiments/024-finding-items/2026-09-30-tpcc-after-1-linux-aarch64.jsonl b/research/experiments/024-finding-items/2026-09-30-tpcc-after-1-linux-aarch64.jsonl
new file mode 100644
index 0000000..4e48295
--- /dev/null
+++ b/research/experiments/024-finding-items/2026-09-30-tpcc-after-1-linux-aarch64.jsonl
@@ -0,0 +1,3 @@
+{"step": "load", "directory": "/dev/shm", "warehouses": 1, "rows": 568758, "generate_s": 0.56, "pure_load_s": 0.92, "sqlite_load_s": 1.61, "sqlite_page_size": 4096, "pure_resident_mib": 38.2, "sqlite_file_mib": 13.8}
+{"step": "run", "system": "pure", "warehouses": 1, "terminals": 64, "transactions_per_second": 35582, "new_orders_per_minute": 951532, "undone_new_orders": 3034, "errors": 0, "new_order": {"done": 320214, "failed": 0, "p50_us": 1536, "p99_us": 6656}, "payment": {"done": 306093, "failed": 0, "p50_us": 1536, "p99_us": 6656}, "order_status": {"done": 28549, "failed": 0, "p50_us": 304, "p99_us": 3456}, "delivery": {"done": 28527, "failed": 0, "p50_us": 1536, "p99_us": 6656}, "stock_level": {"done": 28264, "failed": 0, "p50_us": 336, "p99_us": 3712}, "server_threads": "3", "cpu_us_per_transaction": 46.4, "core_shares": {"pure-owner": 0.77, "pure-checkpoint": 0.01}, "resident_mib": 385.0, "written_bytes_per_transaction": 0.0, "device_bytes_per_transaction": null, "consistency_failures": []}
+{"step": "end", "pure_resident_mib": 385.0, "pure_state_mib": 193.6, "pure_store_mib": 198.7, "sqlite_files_mib": 13.8, "grouped_sqlite_files_mib": 0.0, "pure_counts": {"bursts": 23174, "burst_events": 651885, "checkpoints": 32}}
diff --git a/research/experiments/024-finding-items/2026-09-30-tpcc-after-2-linux-aarch64.jsonl b/research/experiments/024-finding-items/2026-09-30-tpcc-after-2-linux-aarch64.jsonl
new file mode 100644
index 0000000..0a3ba79
--- /dev/null
+++ b/research/experiments/024-finding-items/2026-09-30-tpcc-after-2-linux-aarch64.jsonl
@@ -0,0 +1,3 @@
+{"step": "load", "directory": "/dev/shm", "warehouses": 1, "rows": 568758, "generate_s": 0.56, "pure_load_s": 0.71, "sqlite_load_s": 1.58, "sqlite_page_size": 4096, "pure_resident_mib": 38.9, "sqlite_file_mib": 13.8}
+{"step": "run", "system": "pure", "warehouses": 1, "terminals": 64, "transactions_per_second": 32144, "new_orders_per_minute": 858833, "undone_new_orders": 2719, "errors": 0, "new_order": {"done": 288997, "failed": 0, "p50_us": 1728, "p99_us": 6912}, "payment": {"done": 276707, "failed": 0, "p50_us": 1664, "p99_us": 6656}, "order_status": {"done": 25877, "failed": 0, "p50_us": 336, "p99_us": 3712}, "delivery": {"done": 25795, "failed": 0, "p50_us": 1728, "p99_us": 6656}, "stock_level": {"done": 25502, "failed": 0, "p50_us": 384, "p99_us": 3840}, "server_threads": "3", "cpu_us_per_transaction": 48.7, "core_shares": {"pure-owner": 0.74, "pure-checkpoint": 0.01}, "resident_mib": 353.6, "written_bytes_per_transaction": 0.0, "device_bytes_per_transaction": null, "consistency_failures": []}
+{"step": "end", "pure_resident_mib": 353.6, "pure_state_mib": 176.9, "pure_store_mib": 182.7, "sqlite_files_mib": 13.8, "grouped_sqlite_files_mib": 0.0, "pure_counts": {"bursts": 21004, "burst_events": 588864, "checkpoints": 28}}
diff --git a/research/experiments/024-finding-items/2026-09-30-tpcc-after-3-linux-aarch64.jsonl b/research/experiments/024-finding-items/2026-09-30-tpcc-after-3-linux-aarch64.jsonl
new file mode 100644
index 0000000..af6b785
--- /dev/null
+++ b/research/experiments/024-finding-items/2026-09-30-tpcc-after-3-linux-aarch64.jsonl
@@ -0,0 +1,3 @@
+{"step": "load", "directory": "/dev/shm", "warehouses": 1, "rows": 568758, "generate_s": 0.56, "pure_load_s": 0.71, "sqlite_load_s": 1.58, "sqlite_page_size": 4096, "pure_resident_mib": 38.2, "sqlite_file_mib": 13.8}
+{"step": "run", "system": "pure", "warehouses": 1, "terminals": 64, "transactions_per_second": 44626, "new_orders_per_minute": 1193844, "undone_new_orders": 3830, "errors": 0, "new_order": {"done": 401787, "failed": 0, "p50_us": 1408, "p99_us": 3456}, "payment": {"done": 383595, "failed": 0, "p50_us": 1408, "p99_us": 3456}, "order_status": {"done": 35812, "failed": 0, "p50_us": 256, "p99_us": 1344}, "delivery": {"done": 35769, "failed": 0, "p50_us": 1408, "p99_us": 3456}, "stock_level": {"done": 35586, "failed": 0, "p50_us": 288, "p99_us": 1408}, "server_threads": "3", "cpu_us_per_transaction": 42.6, "core_shares": {"pure-owner": 0.89, "pure-checkpoint": 0.01}, "resident_mib": 467.3, "written_bytes_per_transaction": 0.0, "device_bytes_per_transaction": null, "consistency_failures": []}
+{"step": "end", "pure_resident_mib": 467.3, "pure_state_mib": 237.2, "pure_store_mib": 246.7, "sqlite_files_mib": 13.8, "grouped_sqlite_files_mib": 0.0, "pure_counts": {"bursts": 27798, "burst_events": 817405, "checkpoints": 40}}
diff --git a/research/experiments/024-finding-items/2026-09-30-tpcc-after-4-linux-aarch64.jsonl b/research/experiments/024-finding-items/2026-09-30-tpcc-after-4-linux-aarch64.jsonl
new file mode 100644
index 0000000..1f4fb9d
--- /dev/null
+++ b/research/experiments/024-finding-items/2026-09-30-tpcc-after-4-linux-aarch64.jsonl
@@ -0,0 +1,3 @@
+{"step": "load", "directory": "/dev/shm", "warehouses": 1, "rows": 568758, "generate_s": 0.56, "pure_load_s": 0.71, "sqlite_load_s": 1.57, "sqlite_page_size": 4096, "pure_resident_mib": 38.2, "sqlite_file_mib": 13.8}
+{"step": "run", "system": "pure", "warehouses": 1, "terminals": 64, "transactions_per_second": 44555, "new_orders_per_minute": 1191922, "undone_new_orders": 3830, "errors": 0, "new_order": {"done": 401140, "failed": 0, "p50_us": 1408, "p99_us": 3328}, "payment": {"done": 382996, "failed": 0, "p50_us": 1408, "p99_us": 3328}, "order_status": {"done": 35736, "failed": 0, "p50_us": 256, "p99_us": 1344}, "delivery": {"done": 35691, "failed": 0, "p50_us": 1408, "p99_us": 3328}, "stock_level": {"done": 35534, "failed": 0, "p50_us": 288, "p99_us": 1408}, "server_threads": "3", "cpu_us_per_transaction": 42.7, "core_shares": {"pure-owner": 0.89, "pure-checkpoint": 0.01}, "resident_mib": 466.9, "written_bytes_per_transaction": 0.0, "device_bytes_per_transaction": null, "consistency_failures": []}
+{"step": "end", "pure_resident_mib": 466.9, "pure_state_mib": 236.8, "pure_store_mib": 246.7, "sqlite_files_mib": 13.8, "grouped_sqlite_files_mib": 0.0, "pure_counts": {"bursts": 27532, "burst_events": 816081, "checkpoints": 40}}
diff --git a/research/experiments/024-finding-items/2026-09-30-tpcc-after-5-linux-aarch64.jsonl b/research/experiments/024-finding-items/2026-09-30-tpcc-after-5-linux-aarch64.jsonl
new file mode 100644
index 0000000..c089c78
--- /dev/null
+++ b/research/experiments/024-finding-items/2026-09-30-tpcc-after-5-linux-aarch64.jsonl
@@ -0,0 +1,3 @@
+{"step": "load", "directory": "/dev/shm", "warehouses": 1, "rows": 568758, "generate_s": 0.62, "pure_load_s": 0.9, "sqlite_load_s": 1.68, "sqlite_page_size": 4096, "pure_resident_mib": 38.2, "sqlite_file_mib": 13.8}
+{"step": "run", "system": "pure", "warehouses": 1, "terminals": 64, "transactions_per_second": 32643, "new_orders_per_minute": 872505, "undone_new_orders": 2776, "errors": 0, "new_order": {"done": 293612, "failed": 0, "p50_us": 1728, "p99_us": 6656}, "payment": {"done": 280962, "failed": 0, "p50_us": 1664, "p99_us": 6656}, "order_status": {"done": 26241, "failed": 0, "p50_us": 336, "p99_us": 3712}, "delivery": {"done": 26139, "failed": 0, "p50_us": 1664, "p99_us": 6400}, "stock_level": {"done": 25905, "failed": 0, "p50_us": 368, "p99_us": 3712}, "server_threads": "3", "cpu_us_per_transaction": 48.7, "core_shares": {"pure-owner": 0.75, "pure-checkpoint": 0.01}, "resident_mib": 357.1, "written_bytes_per_transaction": 0.0, "device_bytes_per_transaction": null, "consistency_failures": []}
+{"step": "end", "pure_resident_mib": 357.1, "pure_state_mib": 179.4, "pure_store_mib": 182.7, "sqlite_files_mib": 13.8, "grouped_sqlite_files_mib": 0.0, "pure_counts": {"bursts": 21420, "burst_events": 598014, "checkpoints": 28}}
diff --git a/research/experiments/024-finding-items/2026-09-30-tpcc-after-6-linux-aarch64.jsonl b/research/experiments/024-finding-items/2026-09-30-tpcc-after-6-linux-aarch64.jsonl
new file mode 100644
index 0000000..eabbf86
--- /dev/null
+++ b/research/experiments/024-finding-items/2026-09-30-tpcc-after-6-linux-aarch64.jsonl
@@ -0,0 +1,3 @@
+{"step": "load", "directory": "/dev/shm", "warehouses": 1, "rows": 568758, "generate_s": 0.56, "pure_load_s": 0.77, "sqlite_load_s": 1.6, "sqlite_page_size": 4096, "pure_resident_mib": 38.2, "sqlite_file_mib": 13.8}
+{"step": "run", "system": "pure", "warehouses": 1, "terminals": 64, "transactions_per_second": 43579, "new_orders_per_minute": 1166097, "undone_new_orders": 3735, "errors": 0, "new_order": {"done": 392436, "failed": 0, "p50_us": 1408, "p99_us": 3968}, "payment": {"done": 374594, "failed": 0, "p50_us": 1408, "p99_us": 3840}, "order_status": {"done": 34948, "failed": 0, "p50_us": 256, "p99_us": 1600}, "delivery": {"done": 34891, "failed": 0, "p50_us": 1408, "p99_us": 3840}, "stock_level": {"done": 34722, "failed": 0, "p50_us": 288, "p99_us": 1792}, "server_threads": "3", "cpu_us_per_transaction": 43.0, "core_shares": {"pure-owner": 0.88, "pure-checkpoint": 0.01}, "resident_mib": 457.4, "written_bytes_per_transaction": 0.0, "device_bytes_per_transaction": null, "consistency_failures": []}
+{"step": "end", "pure_resident_mib": 457.4, "pure_state_mib": 232.2, "pure_store_mib": 238.7, "sqlite_files_mib": 13.8, "grouped_sqlite_files_mib": 0.0, "pure_counts": {"bursts": 27631, "burst_events": 798265, "checkpoints": 39}}
diff --git a/research/experiments/024-finding-items/2026-09-30-tpcc-before-1-linux-aarch64.jsonl b/research/experiments/024-finding-items/2026-09-30-tpcc-before-1-linux-aarch64.jsonl
new file mode 100644
index 0000000..4370220
--- /dev/null
+++ b/research/experiments/024-finding-items/2026-09-30-tpcc-before-1-linux-aarch64.jsonl
@@ -0,0 +1,3 @@
+{"step": "load", "directory": "/dev/shm", "warehouses": 1, "rows": 568758, "generate_s": 0.55, "pure_load_s": 0.71, "sqlite_load_s": 1.58, "sqlite_page_size": 4096, "pure_resident_mib": 38.2, "sqlite_file_mib": 13.8}
+{"step": "run", "system": "pure", "warehouses": 1, "terminals": 64, "transactions_per_second": 43185, "new_orders_per_minute": 1155354, "undone_new_orders": 3699, "errors": 0, "new_order": {"done": 388817, "failed": 0, "p50_us": 1472, "p99_us": 3840}, "payment": {"done": 371224, "failed": 0, "p50_us": 1408, "p99_us": 3840}, "order_status": {"done": 34650, "failed": 0, "p50_us": 256, "p99_us": 1472}, "delivery": {"done": 34606, "failed": 0, "p50_us": 1408, "p99_us": 3712}, "stock_level": {"done": 34399, "failed": 0, "p50_us": 288, "p99_us": 1600}, "server_threads": "3", "cpu_us_per_transaction": 43.9, "core_shares": {"pure-owner": 0.88, "pure-checkpoint": 0.01}, "resident_mib": 453.8, "written_bytes_per_transaction": 0.0, "device_bytes_per_transaction": null, "consistency_failures": []}
+{"step": "end", "pure_resident_mib": 453.8, "pure_state_mib": 230.3, "pure_store_mib": 238.7, "sqlite_files_mib": 13.8, "grouped_sqlite_files_mib": 0.0, "pure_counts": {"bursts": 26754, "burst_events": 791032, "checkpoints": 38}}
diff --git a/research/experiments/024-finding-items/2026-09-30-tpcc-before-2-linux-aarch64.jsonl b/research/experiments/024-finding-items/2026-09-30-tpcc-before-2-linux-aarch64.jsonl
new file mode 100644
index 0000000..4bb2a72
--- /dev/null
+++ b/research/experiments/024-finding-items/2026-09-30-tpcc-before-2-linux-aarch64.jsonl
@@ -0,0 +1,3 @@
+{"step": "load", "directory": "/dev/shm", "warehouses": 1, "rows": 568758, "generate_s": 0.56, "pure_load_s": 0.71, "sqlite_load_s": 1.58, "sqlite_page_size": 4096, "pure_resident_mib": 38.2, "sqlite_file_mib": 13.8}
+{"step": "run", "system": "pure", "warehouses": 1, "terminals": 64, "transactions_per_second": 44248, "new_orders_per_minute": 1183944, "undone_new_orders": 3800, "errors": 0, "new_order": {"done": 398450, "failed": 0, "p50_us": 1408, "p99_us": 3840}, "payment": {"done": 380308, "failed": 0, "p50_us": 1408, "p99_us": 3840}, "order_status": {"done": 35467, "failed": 0, "p50_us": 256, "p99_us": 1472}, "delivery": {"done": 35460, "failed": 0, "p50_us": 1408, "p99_us": 3712}, "stock_level": {"done": 35283, "failed": 0, "p50_us": 288, "p99_us": 1536}, "server_threads": "3", "cpu_us_per_transaction": 42.9, "core_shares": {"pure-owner": 0.89, "pure-checkpoint": 0.01}, "resident_mib": 463.8, "written_bytes_per_transaction": 0.0, "device_bytes_per_transaction": null, "consistency_failures": []}
+{"step": "end", "pure_resident_mib": 463.8, "pure_state_mib": 235.4, "pure_store_mib": 246.7, "sqlite_files_mib": 13.8, "grouped_sqlite_files_mib": 0.0, "pure_counts": {"bursts": 27621, "burst_events": 810503, "checkpoints": 40}}
diff --git a/research/experiments/024-finding-items/2026-09-30-tpcc-before-3-linux-aarch64.jsonl b/research/experiments/024-finding-items/2026-09-30-tpcc-before-3-linux-aarch64.jsonl
new file mode 100644
index 0000000..4116a98
--- /dev/null
+++ b/research/experiments/024-finding-items/2026-09-30-tpcc-before-3-linux-aarch64.jsonl
@@ -0,0 +1,3 @@
+{"step": "load", "directory": "/dev/shm", "warehouses": 1, "rows": 568758, "generate_s": 0.56, "pure_load_s": 0.71, "sqlite_load_s": 1.57, "sqlite_page_size": 4096, "pure_resident_mib": 38.9, "sqlite_file_mib": 13.8}
+{"step": "run", "system": "pure", "warehouses": 1, "terminals": 64, "transactions_per_second": 43719, "new_orders_per_minute": 1169901, "undone_new_orders": 3742, "errors": 0, "new_order": {"done": 393711, "failed": 0, "p50_us": 1472, "p99_us": 3712}, "payment": {"done": 375772, "failed": 0, "p50_us": 1408, "p99_us": 3712}, "order_status": {"done": 35030, "failed": 0, "p50_us": 256, "p99_us": 1728}, "delivery": {"done": 35025, "failed": 0, "p50_us": 1408, "p99_us": 3712}, "stock_level": {"done": 34852, "failed": 0, "p50_us": 288, "p99_us": 1792}, "server_threads": "3", "cpu_us_per_transaction": 43.1, "core_shares": {"pure-owner": 0.89, "pure-checkpoint": 0.01}, "resident_mib": 459.1, "written_bytes_per_transaction": 0.0, "device_bytes_per_transaction": null, "consistency_failures": []}
+{"step": "end", "pure_resident_mib": 459.1, "pure_state_mib": 232.9, "pure_store_mib": 238.7, "sqlite_files_mib": 13.8, "grouped_sqlite_files_mib": 0.0, "pure_counts": {"bursts": 27236, "burst_events": 800851, "checkpoints": 39}}
diff --git a/research/experiments/024-finding-items/2026-09-30-tpcc-before-4-linux-aarch64.jsonl b/research/experiments/024-finding-items/2026-09-30-tpcc-before-4-linux-aarch64.jsonl
new file mode 100644
index 0000000..15fa180
--- /dev/null
+++ b/research/experiments/024-finding-items/2026-09-30-tpcc-before-4-linux-aarch64.jsonl
@@ -0,0 +1,3 @@
+{"step": "load", "directory": "/dev/shm", "warehouses": 1, "rows": 568758, "generate_s": 0.56, "pure_load_s": 0.71, "sqlite_load_s": 1.61, "sqlite_page_size": 4096, "pure_resident_mib": 38.2, "sqlite_file_mib": 13.8}
+{"step": "run", "system": "pure", "warehouses": 1, "terminals": 64, "transactions_per_second": 43895, "new_orders_per_minute": 1174382, "undone_new_orders": 3764, "errors": 0, "new_order": {"done": 395225, "failed": 0, "p50_us": 1472, "p99_us": 3712}, "payment": {"done": 377341, "failed": 0, "p50_us": 1408, "p99_us": 3712}, "order_status": {"done": 35184, "failed": 0, "p50_us": 256, "p99_us": 1344}, "delivery": {"done": 35150, "failed": 0, "p50_us": 1408, "p99_us": 3584}, "stock_level": {"done": 34992, "failed": 0, "p50_us": 288, "p99_us": 1472}, "server_threads": "3", "cpu_us_per_transaction": 42.9, "core_shares": {"pure-owner": 0.89, "pure-checkpoint": 0.01}, "resident_mib": 460.2, "written_bytes_per_transaction": 0.0, "device_bytes_per_transaction": null, "consistency_failures": []}
+{"step": "end", "pure_resident_mib": 460.2, "pure_state_mib": 233.7, "pure_store_mib": 238.7, "sqlite_files_mib": 13.8, "grouped_sqlite_files_mib": 0.0, "pure_counts": {"bursts": 27142, "burst_events": 804037, "checkpoints": 39}}
diff --git a/research/experiments/024-finding-items/2026-09-30-tpcc-before-5-linux-aarch64.jsonl b/research/experiments/024-finding-items/2026-09-30-tpcc-before-5-linux-aarch64.jsonl
new file mode 100644
index 0000000..6c90e25
--- /dev/null
+++ b/research/experiments/024-finding-items/2026-09-30-tpcc-before-5-linux-aarch64.jsonl
@@ -0,0 +1,3 @@
+{"step": "load", "directory": "/dev/shm", "warehouses": 1, "rows": 568758, "generate_s": 0.56, "pure_load_s": 0.7, "sqlite_load_s": 1.64, "sqlite_page_size": 4096, "pure_resident_mib": 38.9, "sqlite_file_mib": 13.8}
+{"step": "run", "system": "pure", "warehouses": 1, "terminals": 64, "transactions_per_second": 37963, "new_orders_per_minute": 1015262, "undone_new_orders": 3254, "errors": 0, "new_order": {"done": 341679, "failed": 0, "p50_us": 1536, "p99_us": 4608}, "payment": {"done": 326457, "failed": 0, "p50_us": 1536, "p99_us": 4608}, "order_status": {"done": 30460, "failed": 0, "p50_us": 288, "p99_us": 2304}, "delivery": {"done": 30463, "failed": 0, "p50_us": 1536, "p99_us": 4864}, "stock_level": {"done": 30208, "failed": 0, "p50_us": 320, "p99_us": 2304}, "server_threads": "3", "cpu_us_per_transaction": 45.7, "core_shares": {"pure-owner": 0.82, "pure-checkpoint": 0.01}, "resident_mib": 407.7, "written_bytes_per_transaction": 0.0, "device_bytes_per_transaction": null, "consistency_failures": []}
+{"step": "end", "pure_resident_mib": 407.7, "pure_state_mib": 205.0, "pure_store_mib": 214.7, "sqlite_files_mib": 13.8, "grouped_sqlite_files_mib": 0.0, "pure_counts": {"bursts": 24124, "burst_events": 695431, "checkpoints": 33}}
diff --git a/research/experiments/024-finding-items/2026-09-30-tpcc-before-6-linux-aarch64.jsonl b/research/experiments/024-finding-items/2026-09-30-tpcc-before-6-linux-aarch64.jsonl
new file mode 100644
index 0000000..0a1fa6c
--- /dev/null
+++ b/research/experiments/024-finding-items/2026-09-30-tpcc-before-6-linux-aarch64.jsonl
@@ -0,0 +1,3 @@
+{"step": "load", "directory": "/dev/shm", "warehouses": 1, "rows": 568758, "generate_s": 0.56, "pure_load_s": 0.76, "sqlite_load_s": 1.6, "sqlite_page_size": 4096, "pure_resident_mib": 38.2, "sqlite_file_mib": 13.8}
+{"step": "run", "system": "pure", "warehouses": 1, "terminals": 64, "transactions_per_second": 43848, "new_orders_per_minute": 1173206, "undone_new_orders": 3760, "errors": 0, "new_order": {"done": 394829, "failed": 0, "p50_us": 1472, "p99_us": 3584}, "payment": {"done": 376952, "failed": 0, "p50_us": 1408, "p99_us": 3584}, "order_status": {"done": 35157, "failed": 0, "p50_us": 248, "p99_us": 1344}, "delivery": {"done": 35082, "failed": 0, "p50_us": 1408, "p99_us": 3584}, "stock_level": {"done": 34950, "failed": 0, "p50_us": 272, "p99_us": 1472}, "server_threads": "3", "cpu_us_per_transaction": 42.7, "core_shares": {"pure-owner": 0.89, "pure-checkpoint": 0.01}, "resident_mib": 459.5, "written_bytes_per_transaction": 0.0, "device_bytes_per_transaction": null, "consistency_failures": []}
+{"step": "end", "pure_resident_mib": 459.5, "pure_state_mib": 233.5, "pure_store_mib": 238.7, "sqlite_files_mib": 13.8, "grouped_sqlite_files_mib": 0.0, "pure_counts": {"bursts": 26881, "burst_events": 803187, "checkpoints": 39}}
diff --git a/research/experiments/024-finding-items/bench-seek.c b/research/experiments/024-finding-items/bench-seek.c
new file mode 100644
index 0000000..6be7245
--- /dev/null
+++ b/research/experiments/024-finding-items/bench-seek.c
@@ -0,0 +1,80 @@
+/* Finding items in a keyed list the way TPC-C's stock is found (docs/research/109):
+ *     bench-seek ITEMS OPERATIONS
+ * A list of ITEMS items, five number fields, keyed by the first (keys 1..ITEMS);
+ * then OPERATIONS random keys, four ways: a seek alone; a seek and three
+ * fields read; and three fields read and each changed (journaled); the same
+ * with a share every 30 changes, as a snapshot a save takes. Prints ns each,
+ * and the machine's latency to memory (a random pointer chase over 64 MiB). */
+#include "module-list.h"
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+static uint64_t now_ns(void) {
+    struct timespec t;
+    clock_gettime(CLOCK_MONOTONIC, &t);
+    return (uint64_t)t.tv_sec * 1000000000u + (uint64_t)t.tv_nsec;
+}
+
+static uint64_t state = 0x9e3779b97f4a7c15u;
+static uint64_t next(void) {
+    state ^= state << 13, state ^= state >> 7, state ^= state << 17;
+    return state;
+}
+
+int main(int argc, char **argv) {
+    size_t items = argc > 1 ? strtoull(argv[1], NULL, 10) : 100000, operations = argc > 2 ? strtoull(argv[2], NULL, 10) : 2000000;
+    static const uint8_t numbers[5] = {0};
+    PureList *list = pure_list_new(5, numbers);
+    if (!list || pure_list_keyed(list, 0) != PURE_OK) return 1;
+    for (size_t i = 0; i < items; ++i) {
+        PureCell cells[5] = {{.num = (double)(i + 1)}, {.num = 50}, {.num = 0}, {.num = 0}, {.num = 0}};
+        if (pure_list_insert(list, i, cells, NULL) != PURE_OK) return 1;
+    }
+    pure_list_journal(list, true);
+    double sink = 0;
+    const char *names[4] = {"seek", "seek+3 reads", "seek+3 reads+3 changes", "same, a share each 30"};
+    for (int way = 0; way < 4; ++way) {
+        PureRetired retired = {0};
+        PureList *copy = NULL;
+        uint64_t epoch = 0;
+        uint64_t began = now_ns();
+        for (size_t op = 0; op < operations; ++op) {
+            bool found;
+            size_t at = pure_list_seek(list, 0, (PureCell){.num = (double)(next() % items + 1)}, &found);
+            if (way == 0) { sink += (double)at; continue; }
+            for (unsigned f = 1; f <= 3; ++f) {
+                double value = pure_list_get(list, at, f).num;
+                sink += value;
+                if (way >= 2) pure_list_set(list, at, f, (PureCell){.num = value + 1}, NULL);
+            }
+            if (way >= 2 && op % 64 == 63) pure_list_forget(list, 0);
+            if (way == 3 && op % 30 == 29) {
+                if (copy) {
+                    pure_list_free(copy);
+                    pure_retired_reuse(&retired, &list, 1);
+                }
+                copy = pure_list_share(list, &retired, ++epoch);
+            }
+        }
+        uint64_t took = now_ns() - began;
+        if (copy) pure_list_free(copy);
+        pure_retired_free(&retired);
+        printf("%-26s %7.1f ns\n", names[way], (double)took / (double)operations);
+    }
+    /* The latency to memory: a random cycle through 64 MiB of pointers. */
+    size_t slots = (64u << 20) / sizeof(size_t);
+    size_t *chain = malloc(slots * sizeof(*chain)), *order = malloc(slots * sizeof(*order));
+    for (size_t i = 0; i < slots; ++i) order[i] = i;
+    for (size_t i = slots - 1; i > 0; --i) { size_t j = next() % (i + 1), t = order[i]; order[i] = order[j]; order[j] = t; }
+    for (size_t i = 0; i < slots; ++i) chain[order[i]] = order[(i + 1) % slots];
+    size_t at = order[0];
+    uint64_t began = now_ns();
+    for (size_t i = 0; i < 4000000; ++i) at = chain[at];
+    printf("%-26s %7.1f ns\n", "memory latency", (double)(now_ns() - began) / 4000000.0);
+    sink += (double)at;
+    fprintf(stderr, "%g\n", sink);
+    pure_list_free(list);
+    return 0;
+}
diff --git a/research/experiments/024-finding-items/micro.py b/research/experiments/024-finding-items/micro.py
new file mode 100644
index 0000000..1e80a9e
--- /dev/null
+++ b/research/experiments/024-finding-items/micro.py
@@ -0,0 +1,26 @@
+#!/usr/bin/env python3
+"""bench-seek before and after prefetch.patch, taking turns five times, lists of 100,000 and 400,000 items:
+the median ns of each way and the spread (slowest over fastest), and the load average when it began and ended.
+
+    micro.py DIRECTORY   (holding bench-before and bench-after)"""
+import os
+import statistics
+import subprocess
+import sys
+from pathlib import Path
+
+here = Path(sys.argv[1])
+ways = ['seek', 'seek+3 reads', 'seek+3 reads+3 changes', 'same, a share each 30']
+print('load average at the start:', os.getloadavg())
+for items in (100000, 400000):
+    runs = {'before': [], 'after': []}
+    for _ in range(5):
+        for version in runs:
+            out = subprocess.run([here / f'bench-{version}', str(items), '1500000'], capture_output=True, text=True,
+                                 check=True).stdout.splitlines()[:4]
+            runs[version].append([float(line.split()[-2]) for line in out])
+    for version, measured in runs.items():
+        medians = [statistics.median(m[i] for m in measured) for i in range(4)]
+        spreads = [max(m[i] for m in measured) / min(m[i] for m in measured) for i in range(4)]
+        print(f'{items:>7} {version:<6} ' + '  '.join(f'{w}: {m:.1f} ns (x{s:.2f})' for w, m, s in zip(ways, medians, spreads)))
+print('load average at the end:', os.getloadavg())
diff --git a/research/experiments/024-finding-items/prefetch.patch b/research/experiments/024-finding-items/prefetch.patch
new file mode 100644
index 0000000..e642352
--- /dev/null
+++ b/research/experiments/024-finding-items/prefetch.patch
@@ -0,0 +1,21 @@
+--- a/core/module-list.c
++++ b/core/module-list.c
+@@ -1122,12 +1122,17 @@
+             unsigned taken = upper(g->keys + 1, FANOUT - 1, key.num);
+             start += g->before[taken];
+             node = child(node, taken);
++            if (!node->leaf)
++                for (unsigned i = 0; i < FANOUT; i += 8) __builtin_prefetch(guide(node)->keys + i);
+         }
+         const double *keys = numbers(l, node, field);
+-        if (list->count > PREFETCHED) /* leaves past the caches: the leaf's keys fetched at once, not probe by probe */
++        if (true) /* the leaf's keys fetched at once, not probe by probe */
+             for (unsigned i = 0; i < node->count; i += 8) __builtin_prefetch(keys + i);
+         unsigned low = lower(keys, node->count, key.num);
+         *found = low < node->count && keys[low] == key.num;
++        if (*found) /* the item is read next, a field at a time: its cells, a line each, fetched together */
++            for (unsigned f = 0; f < l->fields; ++f)
++                __builtin_prefetch(l->text_fields[f] ? (const void *)&texts(l, node, f)[low] : (const void *)&numbers(l, node, f)[low]);
+         return start + low;
+     }
+     while (!node->leaf) {
diff --git a/research/experiments/024-finding-items/runs.sh b/research/experiments/024-finding-items/runs.sh
new file mode 100644
index 0000000..ddb740a
--- /dev/null
+++ b/research/experiments/024-finding-items/runs.sh
@@ -0,0 +1,32 @@
+#!/bin/sh
+# The runs of docs/research/109, from the repository's root: the list
+# micro-benchmark before and after prefetch.patch, then TPC-C's pure-serve
+# before and after in turns (the tree is patched to build it, then put back).
+set -e
+out=research/experiments/024-finding-items
+work=$(mktemp -d)
+rest="core/module.c core/module-save.c core/module-text.c core/module-store.c core/flow.c store/store-tree.c store/store-log.c"
+cp core/module-list.c $work/module-list-before.c
+cp core/module-list.c $work/module-list-after.c
+patch -s $work/module-list-after.c $out/prefetch.patch
+for version in before after; do
+    cc -O2 -g -std=c17 -D_GNU_SOURCE -Icore -Istore $out/bench-seek.c $work/module-list-$version.c $rest -pthread -lm \
+        -o $work/bench-$version
+done
+python3 $out/micro.py $work > $out/2026-09-30-micro-linux-aarch64.txt
+
+make -s build/pure-serve
+cp build/pure-serve $work/pure-serve-before
+cp $work/module-list-after.c core/module-list.c
+make -s build/pure-serve
+cp build/pure-serve $work/pure-serve-after
+cp $work/module-list-before.c core/module-list.c
+make -s build/pure-serve
+for round in 1 2 3 4 5 6; do
+    first=before second=after
+    if [ $((round % 2)) = 0 ]; then first=after second=before; fi
+    for version in $first $second; do
+        python3 benchmarks/tpcc/run.py --serve $work/pure-serve-$version --warehouses 1 --check 0 --terminals 64 \
+            --sqlite-threads '' --sqlite-group '' --seconds 20 > $out/2026-09-30-tpcc-$version-$round-linux-aarch64.jsonl
+    done
+done