Merlin Moncure wrote:
On 8/8/07, Omar Bettin <[EMAIL PROTECTED]> wrote:
Hi,
I have installed postgresql to my client as a server for a progam
(libpq.dll/VCL based) that I wrote for them.
Every is working fine, but I noted some general slowness, compared with an
older database system (iAnywhere ADS)
due (I think) to the text based communication protocol.
you should maybe report a couple of specific things (explain analyze,
etc) for analysis and make sure your expectations are reasonable. It
is possible simple configuration issues or query changes might be the
answer here, then again, maybe not.
I think this is not necessary because I have used the same
application with two different servers and you can see the speed
differences just using it.
I know there is the possibility to adopt a ssl compressed connection but I
think a pure compressed connections could be better.
I think you are looking in the wrong direction here.
So, I have studied the postgresql sources and I have tried to implement some
compression between the backend and the frontend,
using pglz_compress/pglz_decompress on be-secure.c and fe-secure.c.
At the moment is working good on a local configuration, got some problems on
a remote connection due I think a different way to communicate.
AFAIK, the fastest possible way to get data off the server, skipping
all data and text processing is to write a SPI routine, and stream the
data out locally to the server. I am doing exactly this in a
particular problem that requires high performance and I can tell you
that SPI is fast.
http://developer.postgresql.org/pgdocs/postgres/spi-examples.html
That way you will bypass the protocol completely. On my computer, I
get roughly 300k records/sec raw read performance using libpq and
about 1.3m records sec using a hacked SPI and streaming to disk. This
may not be helpful for your application but if you are exploring ways
to bypass protocol overhead this is where I would start.
Interesting,do you thing that is possible to implement some send()
in the interface?
By the way, your problem might be the VCL driver you are using to
access the database. The highest performance driver I have used
(which wraps libpq) is the Zeos library which is very fast.
I have tried ZeosLib and for me is unusable (too slow), I use a
strong modified PostgresDAC.
There are other ways (other than be-secure and fe-secure) with which the
backend comunicate with the frontend?
And, do you think this solution could speed up something?
Once again, I would start by looking at your application and posting
here to make sure you are looking at the right bottlenecks (you
_suspect_ the protocol is the problem, but is it really?).
this means:
* explain analyze/queries (w/how fast you think it should be going)
* relevant .conf settings
* time measurements from the app
merlin
I just switch form Application1 (IAnywhere Ads) to Application2
(Postgresql) optimizing the VCL (strong modifications to PostgresDAC
sources) and sow the results.
My application needs to full open some tables and with this protocol
is like to download a long text file.
omar
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