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Re: [eclipselink-dev] Query retry limited to ReadOnly Queries
I believe it is because inside a transaction it means the whole transactional context is now invalid and needs to be retried.  This is best  handled by the application since the eclipselink does not track every statement issued in the transaction.

Best regards
Chris

On 2011-10-07, at 4:24 PM, sridhar baratam <sridhar_baratam@xxxxxxxxx> wrote:

Hi Tom,
 
This is the code excerpt from AbstractSession.class inside the function:
 
public Object executeQuery(DatabaseQuery query, AbstractRecord row, int retryCount) throws DatabaseException {
-
-
-
-

//if this query is a read query outside of a transaction then we may be able to retry the query

if (!isInTransaction() && query.isReadQuery()) {

//was the failure communication based? (ie timeout)

if (databaseException.isCommunicationFailure()) {

Object[] args = new Object[1];
 
 
 
Also, from the documentation, I see the following:
 
void org.eclipse.persistence.sessions.DatabaseLogin.setDelayBetweenConnectionAttempts(int delayBetweenConnectionAttempts)
PUBLIC: Stores the number of milliseconds that EclipseLink will wait between attempts to reconnect a DatabaseConnection in the case EclipseLink is attempting to retry a query. EclipseLink will retry a read query outside of a transaction if EclipseLink can determine that a communication error occurred with the database.
Parameters:
delayBetweenConnectionAttempts
 
Open Declaration void org.eclipse.persistence.sessions.DatabaseLogin.setQueryRetryAttemptCount(int queryRetryAttemptCount)

 
PUBLIC: Set the number of attempts EclipseLink should make to re-connect to a database and re-execute a query after a query has failed because of a communication issue. EclipseLink will only attempt to reconnect when EclipseLink can determine that a communication failure occurred on a read query executed outside of a transaction. By default EclipseLink will attempt to retry the query 3 times, by setting this value to 0 EclipseLink will not retry queries.
Parameters:
queryRetryAttemptCount
Thanks
Sridhar

--- On Fri, 10/7/11, Tom Ware <tom.ware@xxxxxxxxxx> wrote:

From: Tom Ware <tom.ware@xxxxxxxxxx>
Subject: Re: [eclipselink-dev] Query retry limited to ReadOnly Queries
To: eclipselink-dev@xxxxxxxxxxx
Date: Friday, October 7, 2011, 3:10 PM

Can you point me to the code that just retrys for read only queries.  I am
looking at AbstractSession.executeQuery() in our 2.3.1 stream and I see no such
restriction.

-Tom

On 05/10/2011 4:19 PM, sridhar baratam wrote:
> Hi All,
> It appears the query retry logic will only happen for READONLY queries on a
> connection communication error. Is there a specific reason for that? A
> non-READONLY query can still fail on a communication error. Due to this specific
> restriction, I believe it puts the onus back on the application to code around
> these failures for non-readonly queries during communication errors. This may
> not be optimal considering the whole logic behind using JPA where developers can
> focus on the business logic and do not have to worry about the database stuff. I
> could be wrong here and wonder if there is a specific reason to have the retry
> limited to READONLY queries.
> Can someone throw somelight in this regard?
> Thanks
> Sridhar
>
>
>
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