transactions getting slon in councurrent environment

From: Tigran Mkrtchyan <tigran(dot)mkrtchyan(at)desy(dot)de>
To: pgsql-bugs(at)postgresql(dot)org
Subject: transactions getting slon in councurrent environment
Date: 2006-12-28 12:12:22
Message-ID: 4593B4A6.20202@desy.de
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Dear PostgreSQL gurus,

I got a incorrect or unexpected behavior in concurrent environment.
Luckily, I was able to localize it and create an example:

My setup:

Postgres 8.2 ( with 8.1 the same effect )
Linux ( with Solaris the same effect )
java 1.5, JDBC driver 8.2-504.jdbc3 ( with earlier versions the same effect )

The table:

create table t_jtest (
ikey CHAR(36) primary key,
ivalue integer not null
);

The appication:

Client 1:

autocommit off

loop:
INSERT INTO t_jtest VALUES (?,?)
UPDATE t_jtest SET ivalue=? where ikay=?
commit

Client 2:
autocommit off
"SELECT COUNT(*) FROM t_jtest"

do nothing

The effect is that time, which is needed by Client 1 is growing, unless I add a
commit into client 2.

Is it normal behavior?

Both application attached. To run:

javac *.java

in terminal 1:

java -cp postgresql-8.2-504.jdbc3.jar DbIject

in terminal 2:

ava -cp postgresql-8.2-504.jdbc3.jar Spy

Regards,
Tigran.

________________________________________________________________________
Tigran Mkrtchyan DESY, IT,
tigran(dot)mkrtchyan(at)desy(dot)de Notkestrasse 85,
Tel: + 49 40 89983946 Hamburg 22607,
Fax: + 49 40 89984429 Germany.

Attachment Content-Type Size
DbIject.java text/x-java 1.8 KB
Spy.java text/x-java 918 bytes

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