I wrote:
> FWIW, my own experiments with tests like this suggest that PG is at
> worst about 2x slower than mysql for trivial queries. If you'd reported
> a result in that ballpark I'd have accepted it as probably real. 6x I
> don't believe though ...
Just for amusement's sake, I tried compiling up super-smack on my own
machine, and got results roughly in line with what I would've expected.
Machine: dual Xeon EM64T, forget the clock rate at the moment, running
Fedora Core 4 (kernel 2.6.15-1.1831_FC4smp); hyperthreading enabled
Postgres: fairly recent CVS tip, no special build options except
--enable-debug, no changes to default runtime configuration options
MySQL: 5.0.18, current Red Hat RPMs, no changes to default configuration
The "select" test, with 1 and 10 clients:
$ super-smack -d pg select-key.smack 1 10000
Query Barrel Report for client smacker1
connect: max=0ms min=-1ms avg= 3ms from 1 clients
Query_type num_queries max_time min_time q_per_s
select_index 20000 0 0 3655.24
$ super-smack -d pg select-key.smack 10 10000
Query Barrel Report for client smacker1
connect: max=54ms min=4ms avg= 12ms from 10 clients
Query_type num_queries max_time min_time q_per_s
select_index 200000 0 0 7431.20
$ super-smack -d mysql select-key.smack 1 10000
Query Barrel Report for client smacker1
connect: max=0ms min=-1ms avg= 0ms from 1 clients
Query_type num_queries max_time min_time q_per_s
select_index 20000 0 0 6894.03
$ super-smack -d mysql select-key.smack 10 10000
Query Barrel Report for client smacker1
connect: max=14ms min=0ms avg= 5ms from 10 clients
Query_type num_queries max_time min_time q_per_s
select_index 200000 0 0 16798.05
The "update" test, with 1 and 10 clients:
$ super-smack -d pg update-select.smack 1 10000
Query Barrel Report for client smacker
connect: max=0ms min=-1ms avg= 4ms from 1 clients
Query_type num_queries max_time min_time q_per_s
select_index 10000 0 0 1027.49
update_index 10000 0 0 1027.49
$ super-smack -d pg update-select.smack 10 10000
Query Barrel Report for client smacker
connect: max=13ms min=5ms avg= 8ms from 10 clients
Query_type num_queries max_time min_time q_per_s
select_index 100000 1 0 1020.96
update_index 100000 28 0 1020.96
The above is with fsync on (though I think this machine's disk lies
about write complete so I'd not trust it as production). With fsync off,
$ super-smack -d pg update-select.smack 1 10000
Query Barrel Report for client smacker
connect: max=0ms min=-1ms avg= 3ms from 1 clients
Query_type num_queries max_time min_time q_per_s
select_index 10000 0 0 1478.25
update_index 10000 0 0 1478.25
$ super-smack -d pg update-select.smack 10 10000
Query Barrel Report for client smacker
connect: max=35ms min=5ms avg= 21ms from 10 clients
Query_type num_queries max_time min_time q_per_s
select_index 100000 1 0 3067.68
update_index 100000 1 0 3067.68
versus mysql
$ super-smack -d mysql update-select.smack 1 10000
Query Barrel Report for client smacker
connect: max=0ms min=-1ms avg= 0ms from 1 clients
Query_type num_queries max_time min_time q_per_s
select_index 10000 0 0 4101.43
update_index 10000 0 0 4101.43
$ super-smack -d mysql update-select.smack 10 10000
Query Barrel Report for client smacker
connect: max=3ms min=0ms avg= 0ms from 10 clients
Query_type num_queries max_time min_time q_per_s
select_index 100000 1 0 5388.31
update_index 100000 6 0 5388.31
Since mysql is using myisam tables (ie not transaction safe), I think
the fairest comparison is to the fsync-off numbers.
regards, tom lane
---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
choose an index scan if your joining column's datatypes do not
match
