Patched
------
        relname        |   nrows   | blk_before | mb_before | blk_after | mb_after |  diff
-----------------------+-----------+------------+-----------+-----------+----------+--------
 pgbench_accounts      | 300000000 |    4918033 |   38422.1 |   5067500 |  39589.8 |  +3.0%
 accounts_mtime        | 300000000 |    1155119 |    9024.4 |   1283441 |  10026.9 | +11.1%
 fiver                 | 300000000 |     427039 |    3336.2 |    429101 |   3352.4 |  +0.5%
 pgbench_accounts_pkey | 300000000 |     822573 |    6426.4 |    826056 |   6453.6 |  +0.4%
 score                 | 300000000 |     284022 |    2218.9 |    285465 |   2230.2 |  +0.5%
 tenner                | 300000000 |     346050 |    2703.5 |    347695 |   2716.4 |  +0.5%
(6 rows)

DB size: 65.2..67.5 (+2.3GB / +3.5%)

scaling factor: 3000
query mode: simple
number of clients: 8
number of threads: 2
duration: 14400 s
number of transactions actually processed: 31909450
latency average = 3.610 ms
tps = 2215.933633 (including connections establishing)
tps = 2215.933884 (excluding connections establishing)
statement latencies in milliseconds:
         0.001  \set aid1 random_gaussian(1, 100000 * :scale, 2.0)
         0.001  \set aid2 random_gaussian(1, 100000 * :scale, 2.5)
         0.000  \set delta random(-5000, 5000)
         0.034  BEGIN;
         0.452  UPDATE pgbench_accounts SET abalance = abalance + :delta WHERE aid = :aid1;
         0.194  SELECT abalance FROM pgbench_accounts WHERE aid = :aid2;
         2.926  END;

scaling factor: 3000
query mode: simple
number of clients: 8
number of threads: 2
duration: 14400 s
number of transactions actually processed: 7078811
latency average = 16.274 ms
tps = 491.583735 (including connections establishing)
tps = 491.583794 (excluding connections establishing)
statement latencies in milliseconds:
         0.002  \set aid2 random_gaussian(1, 100000 * :scale, 3.0)
         0.298  SELECT abalance FROM pgbench_accounts WHERE aid = :aid2;
         3.190  INSERT INTO pgbench_accounts
        12.788  DELETE FROM pgbench_accounts WHERE aid IN

scaling factor: 3000
query mode: simple
number of clients: 1
number of threads: 1
duration: 14400 s
number of transactions actually processed: 40
latency average = 363313.472 ms
tps = 0.002752 (including connections establishing)
tps = 0.002752 (excluding connections establishing)
statement latencies in milliseconds:
    363313.426  SELECT abalance, pg_sleep(300) FROM pgbench_accounts WHERE mtime > now() - INTERVAL '15min' ORDER BY aid LIMIT 1;