PM41088: JIRA OPENJPA-1376 DEFECT BACKPORTED TO V7 OPENJPA 1.2.X

Fixes are available

APAR status

Closed as program error.

Error description

IBM customers requested to backport JIRA OPENJPA-1376 defect to
WebSphere Application Server V7 (OpenJPA 1.2.x).
https://issues.apache.org/jira/browse/OPENJPA-1376

Local fix

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N/A.
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Problem summary

****************************************************************
* USERS AFFECTED:  All users of IBM WebSphere Application      *
*                  Server versions V7.0.0 and V8.0.0 who make  *
*                  use of the 'allocationSize' when using the  *
*                  @SequenceGenerator annotation.              *
****************************************************************
* PROBLEM DESCRIPTION: OpenJPA's implementation of the         *
*                      allocationSize in a @SequenceGenerator  *
*                      is incorrectly implemented.             *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
The Javadoc for the 'allocationSize' property of the
@SequenceGenerator annotation defines the 'allocationSize' as
follows: "The amount to increment by when allocating sequence
numbers from the sequence."  OpenJPA is using this value as a
caching value.  That is, when generating a native sequence, an
SQL like the following my be generated:
CREATE SEQUENCE entityE2_seq_gen START WITH 1 INCREMENT BY 50
CACHE 50
In this SQL statement, OpenJPA is using a 'CACHE 50'
statement, where the value 50 is the allocationSize.  By using
caching, OpenJPA is requesting a sequence value from the
database each time it needs a new sequence.  The database is
in turning caching sequence values.  This results in extra
calls to the database.  A more efficient approach would be for
OpenJPA to cache the sequence value in memory, rather than
relying on the database, and thus honoring the true meaning of
'allocationSize'.  Allocating values in memory allows the
OpenJPA runtime to avoid accessing the database for every
sequence request.  That is, when 'allocationSize' is set to
50, OpenJPA will set aside the next 50 numbers each time it
accesses the sequence, which in turn means it only has to make
a database trip to get new sequence numbers once every 50
sequence number requests.  In this case, a sequence similar to
the following should be generated:
CREATE SEQUENCE entityE2_seq_gen START WITH 1 INCREMENT BY 50

Problem conclusion

To enable the code of this fix, please use the
following JVM system property:

-Dopenjpa.jdbc.DBDictionary=useNativeSequenceCache=false

Or add the following to your persistence.xml file:

<property name="openjpa.jdbc.DBDictionary"
value="useNativeSequenceCache=false"/>

With this fix, and the above system property, OpenJPA will use
the 'allocationSize' as intended (i.e. as the increment when
allocation sequence numbers).

The fix for this APAR is currently targeted for inclusion in
Service Levels (Fix Packs) 7.0.0.21 and 8.0.0.2 of WebSphere
Application Server versions 7.0.0 and 8.0.0.

Please refer to the recommended updates page for delivery
information:
http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980

Temporary fix

Comments

APAR Information

APAR number
PM41088
Reported component name
WEBS APP SERV N
Reported component ID
5724H8800
Reported release
700
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2011-06-08
Closed date
2011-08-30
Last modified date
2011-08-30

APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:

PM45107

Fix information

Fixed component name
WEBS APP SERV N
Fixed component ID
5724H8800

Applicable component levels

R700 PSY
UP
R800 PSY
UP

[{"Business Unit":{"code":"BU059","label":"IBM Software w\/o TPS"},"Product":{"code":"SSEQTP","label":"WebSphere Application Server"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"7.0","Line of Business":{"code":"LOB45","label":"Automation"}}]

Document Information

Modified date:
27 October 2021

Tips

PM41088: JIRA OPENJPA-1376 DEFECT BACKPORTED TO V7 OPENJPA 1.2.X

Fixes are available

Subscribe

APAR status

Closed as program error.

Error description

Local fix

Problem summary

Problem conclusion

Temporary fix

Comments

APAR Information

APAR number

Reported component name

Reported component ID

Reported release

Status

PE

HIPER

Special Attention

Submitted date

Closed date

Last modified date

APAR is sysrouted FROM one or more of the following:

APAR is sysrouted TO one or more of the following:

Fix information

Fixed component name

Fixed component ID

Applicable component levels

R700 PSY

R800 PSY

Document Information

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