From: Craig Ringer <craig@postnewspapers.com.au>
To: firerox@centrum.cz
Cc: pgsql-performance@postgresql.org
Subject: Re: slow pg_connect()
Date: Mon, 24 Mar 2008 16:58:16 +0900
Message-ID: <47E75F18.9060206@postnewspapers.com.au> (raw)
In-Reply-To: <200803240840.8128@centrum.cz>
References: <200803240840.8128@centrum.cz>
firerox@centrum.cz wrote:
> It takes more then 0.05s :(
>
> Only this function reduce server speed max to 20request per second.
>
If you need that sort of frequent database access, you might want to
look into:
- Doing more work in each connection and reducing the number of
connections required;
- Using multiple connections in parallel;
- Pooling connections so you don't need to create a new one for every job;
- Using a more efficient database connector and/or language;
- Dispatching requests to a persistent database access provider that's
always connected
However, your connections are indeed taking a long time. I wrote a
trivial test using psycopg for Python and found that the following script:
#!/usr/bin/env python
import psycopg
conn = pyscopg.connect("dbname=testdb")
generally took 0.035 seconds (350ms) to run on my workstation -
including OS process creation, Python interpreter startup, database
interface loading, connection, disconnection, and process termination.
A quick timing test shows that the connection/disconnection can be
performed 100 times in 1.2 seconds:
import psycopg
import timeit
print timeit.Timer('conn = psycopg.connect("dbname=craig")', 'import
psycopg').timeit(number=100);
... and this is still with an interpreted language. I wouldn't be too
surprised if much better again could be achieved with the C/C++ APIs,
though I don't currently feel the desire to write a test for that.
--
Craig Ringer
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To: pgsql-performance@postgresql.org
Cc: craig@postnewspapers.com.au, firerox@centrum.cz
Subject: Re: slow pg_connect()
In-Reply-To: <47E75F18.9060206@postnewspapers.com.au>
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