RE: Anyone seen weblogic do this?

  • From: Casey Dyke <cdyke@xxxxxxxxxxxx>
  • To: "'oracle-l@xxxxxxxxxxxxx'" <oracle-l@xxxxxxxxxxxxx>
  • Date: Fri, 2 Jul 2004 18:03:05 +0200

We had some fun with that setting, to say the least.  you can see the
settings in either the weblogic console (GUI) or weblogic "repository" (ie:
config.xml).  rather "inventive" admin saw application performance
(admittedly, it was in a dev environment thankfully) suddenly plummet.
seems a trusty admin had reset the table setting to query a 2 million+ row
table.  we never could extract exactly why he chose that table.  suffice to
say it took some tracing (yes, 10046) to figure out what the problem was (it
manifested itself as a screen "hang" ...).  it was quite funny actually.
for those who are curious:

1.) console

select services, JDBC, Connection Pools, {connection pool}, Connections,
Advanced Settings 

scroll down and you'll see them there.  table setting down at the bottom of
the page.

8< (from a console)
Test Reserved Connections
Specifies whether WebLogic Server tests a connection before giving it to the
client. (You must specify a Test Table Name below.)

Test Created Connections
Specifies whether WebLogic Server tests a connection after creating it but
before adding it to the list of connections available in the pool. (You must
specify a Test Table Name.)

Test Released Connections
Specifies whether WebLogic Server tests a connection before returning it to
this JDBC connection pool. (You must specify a Test Table Name.)

2.) domain directory config.xml

<JDBCConnectionPool DriverName="oracle.jdbc.driver.OracleDriver"
.. snip ..
TestConnectionsOnCreate="true" TestConnectionsOnRelease="true"
TestConnectionsOnReserve="true" TestFrequencySeconds="600"
TestTableName="SQL SELECT 1 FROM DUAL" ***snip***"/>


A client of mine recently experienced a similar phemonemon, whereby for them
Weblogic was generating hundreds per minute of "select count(*) from dual;"
SQL statements against their Oracle database.  It turns out there are
Weblogic configuration options to "TestConnectionsUponReserve" and
"TestConnectionsUponRelease" which they had unintentionally selected; these
options cause the select count(*) to be specified against whatever table
name (typically "dual") is specified elsewhere among these configuration


Larry Klein
Hotsos Enterprises, Ltd.
630-513-8010 (Chicago office)
630-240-1190 (cellphone)

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