[infinispan-dev] PutForExternalRead and autoCommit

[Galder Zamarreño]

It's on my TODO list to create a wiki on it: https://issues.jboss.org/browse/ISPN-1120

The javadoc should be clear enough but basically, it's a put operation geared towards best-effort, when you're trying to put somewhere read from an external source.

http://www.slideshare.net/galderz/infinispan-for-dummies - slide 12 for characteristics of a PFER as opposed to a Put

On Nov 17, 2011, at 9:36 AM, Sanne Grinovero wrote:

> Hi Galder,
> could you explain some details of the use case / requirements of
> putForExternalRead ? I'm assuming you're talking about the Hibernate
> 2nd level cache, but I don't know exactly how that is designed, do we
> have some documentation about it?
> 
> Cheers,
> Sanne
> 
> On 17 November 2011 09:30, Galder Zamarreño <galder.zamarreno at redhat.com> wrote:
>> Hi,
>> 
>> Forcing caches to be either transactional or non transactional caches causes some issues with operations such as putForExternalRead with default configuration options.
>> 
>> Assuming we have a transactional cache, if autoCommit is on (default), putForExternalRead will:
>> 1. Suspend the ongoing transaction
>> 2. Will create a brand new transaction due to implicit transaction creation logic in auto commit.
>> 
>> This is not good.
>> 
>> I don't think we can just disable autoCommit globally if someone calls putForExternalRead because there might other operations not called within a transaction, but there's a point to be made here:
>> The whole point of calling PFER is to suspend on-going transactions, so it kinda implies that transactions are managed externally already.
>> 
>> If we don't disable autoCommit globally, there's a few things that we should consider doing:
>> 1. Print a WARN if PFER is called and autoCommit is on?
>> 2. Apart from the message, some kind of way for putForExternalRead to instruct the implicit transaction logic to avoid creating a new transaction in this case.
>> 
>> WDYT?
>> --
>> Galder Zamarreño
>> Sr. Software Engineer
>> Infinispan, JBoss Cache
>> 
>> 
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>> 
> 
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--
Galder Zamarreño
Sr. Software Engineer
Infinispan, JBoss Cache