Re: Patch: fix lock contention for HASHHDR.mutex

> Oops, 3.5-4 _times_ more TPS, i.e. 2206 TPS vs 546 TPS.

In fact these numbers are for similar but a little bit different
benchmark (same schema without checks on child tables). Here are exact
numbers for a benchmark described above.

Before:

$ pgbench -j 64 -c 64 -f pgbench.sql -T 30 my_database
transaction type: Custom query
scaling factor: 1
query mode: simple
number of clients: 64
number of threads: 64
duration: 30 s
number of transactions actually processed: 20433
latency average: 93.966 ms
tps = 679.698439 (including connections establishing)
tps = 680.353897 (excluding connections establishing)

$ pgbench -j 64 -c 64 -f pgbench.sql -T 30 my_database
transaction type: Custom query
scaling factor: 1
query mode: simple
number of clients: 64
number of threads: 64
duration: 30 s
number of transactions actually processed: 19111
latency average: 100.466 ms
tps = 635.763523 (including connections establishing)
tps = 636.112682 (excluding connections establishing)

$ pgbench -j 64 -c 64 -f pgbench.sql -T 30 my_database
transaction type: Custom query
scaling factor: 1
query mode: simple
number of clients: 64
number of threads: 64
duration: 30 s
number of transactions actually processed: 19218
latency average: 99.906 ms
tps = 639.506848 (including connections establishing)
tps = 639.838757 (excluding connections establishing)

After:

$ pgbench -j 64 -c 64 -f pgbench.sql -T 30 my_database
transaction type: Custom query
scaling factor: 1
query mode: simple
number of clients: 64
number of threads: 64
duration: 30 s
number of transactions actually processed: 95900
latency average: 20.021 ms
tps = 3194.142762 (including connections establishing)
tps = 3196.091843 (excluding connections establishing)

$ pgbench -j 64 -c 64 -f pgbench.sql -T 30 my_database
transaction type: Custom query
scaling factor: 1
query mode: simple
number of clients: 64
number of threads: 64
duration: 30 s
number of transactions actually processed: 96837
latency average: 19.827 ms
tps = 3225.822355 (including connections establishing)
tps = 3227.762847 (excluding connections establishing)

$ pgbench -j 64 -c 64 -f pgbench.sql -T 30 my_database
transaction type: Custom query
scaling factor: 1
query mode: simple
number of clients: 64
number of threads: 64
duration: 30 s
number of transactions actually processed: 96143
latency average: 19.970 ms
tps = 3202.637126 (including connections establishing)
tps = 3204.070466 (excluding connections establishing)

Ratio:

$ python

min(3194.0, 3225.0, 3202.0) / max(679.0, 635.0, 639.0)
4.703976435935199