Tom Lane wrote:
> There might be some argument for providing a client option to disable
> compression, but it should not be forced, and it shouldn't even be the
> default. But before adding YA connection option, I'd want to see some
> evidence that it's useful over non-local connections.
Here are numbers from a test via LAN.
The client machine has OpenSSL 0.9.8e, the server OpenSSL 1.0.0.
The client command run was
echo 'select ...' | time psql "host=..." -o /dev/null
and \timing was turned on in .psqlrc
In addition to the oprofile data I collected three times:
- the duration as shown in the server log
- the duration as shown by \timing
- the duration of the psql command as measured by "time"
Without patch:
duration: 5730.996 ms (log), 5975.093 ms (\timing), 22.87 s (time)
samples % image name symbol name
4428 80.2029 libz.so.1.2.3 /lib64/libz.so.1.2.3
559 10.1250 postgres hex_encode
361 6.5387 libcrypto.so.1.0.0 /usr/lib64/libcrypto.so.1.0.0
83 1.5034 libc-2.12.so memcpy
With patch:
duration: 3001.009 ms (log), 3243.690 ms (\timing), 20.27 s (time)
samples % image name symbol name
1072 58.0401 libcrypto.so.1.0.0 /usr/lib64/libcrypto.so.1.0.0
587 31.7813 postgres hex_encode
105 5.6849 libc-2.12.so memcpy
I think this makes a good case for disabling compression.
Yours,
Laurenz Albe