Performance-Problem With Nclob-Fields With Oracle 10g And WebLogicServer

(Doc ID 874379.1)

Last updated on NOVEMBER 05, 2016

Applies to:

Oracle Weblogic Server - Version: 8.1 to 10.3.1
Information in this document applies to any platform.

Symptoms

There is a performance problem which is related to the storing of foreign-language texts (e.g. thai) in NCHAR columns in Oracle Database 10g. Using CMP with Oracle 10g and has NClob column in DB, WLS has to use system property -Doracle.jdbc.defaultnchar=true.

This flag is document within the Oracle Database documentationed
http://download.oracle.com/docs/cd/B19306_01/java.102/b14355/global.htm#CHDHHJDB

Once this value is set, any database requests now lasts for a much extended period of time, in the case that was seen, queries took approximately 5 minutes instead of the expected 2 seconds before the property was set. This is because, after the property was set to true, a full table scan is being executed instead of a query using the primary key.

Cause

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