Re: A couple of questions

Paul,

The problem is likely a bug in the driver, the server doesn't have any
issues with this query.

The difference between the jars is which jdk is used. The one you are
using is for a java version 1.1, which version of java are you using?

Dave

Paul Tomblin wrote:

> I'm using Postgres from a RedHat RPM postgresql-jdbc-7.2.4-5.73 on an
> installed base of a few hundred RedHat 7.3 machines. (Upgrading to
> Fedora Core 2 is in the not-near-enough future.) For historical
> reasons, our Java code uses the /usr/share/pgsql/jdbc7.1-1.1.jar that
> comes in that RPM, even though there are three other jars with higher
> version numbers.
>
> On these systems, we have several programs that access the database,
> and some of them are multi-threaded. There is one table in particular
> that's giving me trouble. It has a bunch of configuration parameters
> stored as keys and values, with both the keys and values being
> character strings. The initial key/value pairs are loaded in at
> creation time, but they are frequently updated using "UPDATE sys_info
> SET VALUE = ? WHERE KEY = ?".
>
> cosdb=> \d sys_info
> Table "sys_info"
> Column | Type | Modifiers
> --------+------------------------+-----------
> key | character varying(50) | not null
> value | character varying(128) |
> Primary key: sys_info_pkey
>
> Occassionally, one of the programs will suddenly act like one of the
> keys disappeared. Either I'll get a null pointer exception in
> org.postgresql.jdbc2.ResultSet.next(ResultSet.java:116) or I'll get a
> NumberFormatException when parsing one of the values that should
> always be an integer. As far as I can tell, at the time this happens
> there are no other threads in that program updating the database in
> any way, although there is a distinct possibility that another program
> is doing so.
>
> So my questions to you:
>
> 1. Are there any known concurrency issues where one program is doing
> an UPDATE on a table when another program is doing a query on it?
>
> 2. If there are known problems, would putting the UPDATE in a
> transaction help?
>
> 3. What is the diffence between the various jdbc*.jar files in the
> RPM, and should I switch to one of the other ones?
>
> Thank you.
>
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Dave Cramer
http://www.postgresintl.com
519 939 0336
ICQ#14675561