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ORACLE PGA IS CONSUMED MORE WITH XML TYPES (Doc ID 970847.1)

Last updated on SEPTEMBER 19, 2019

Applies to:

Oracle Database - Enterprise Edition - Version 11.1.0.6 to 11.2.0.1 [Release 11.1 to 11.2]
Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Express Cloud Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Information in this document applies to any platform.
NOTE: In the images and/or the document content below, the user information and data used represents fictitious data. Any similarity to actual persons, living or dead, is purely coincidental and not intended in any manner.

Symptoms

Customer is using a c++ application that is consuming too much PGA memory

EXAMPLE
About the application:
This is a C++ application running on Redhat Enterprise Linux. Along with our existing legacy data we are using sql statements to perform DML on our table which has a BinaryXML column. The table is defined as :

create table test_testxml(id number, otp_spec xmltype) xmltype otp_spec store as securefile binary xml;

We created an index on the table using:
ALTER TABLE TEST_TESTXML
add CONSTRAINT id XML_pk PRIMARY KEY (ID);

We are going with the approach of passing raw XML in our SQL query and the database encodes the XML to BinaryXML. We are essentially using a char* with a length parameter to perform our operations viz read/write/update.
The sqls for read/write/update look like:

select x.otp_spec.getClobval() from test.test_testxml x where x.id = :id

update test.test_testxml set otp_spec = :xml where id = :id

insert into test.test_testxml(id, otp_spec) values :id, :xml)

Memory is consumed under the following heap:

HEAP DUMP heap name="koh dur heap d"

Cause

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In this Document
Symptoms
Cause
Solution


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