[keycloak-dev] @Column.updatable=false

[Bill Burke]

Not sure on @DynamicUpdate...That screws with query caching. Not sure
of the advantages/disadvantages

On Mon, Sep 11, 2017 at 11:42 AM, Hynek Mlnarik <hmlnarik at redhat.com> wrote:
> The updatable=false causes the column not to be in UPDATE statements
> which is beneficial for several reasons:
>
> * UPDATEs update less columns - thats always positive
> * Database vendor _might_ (and some do) take advantage of the affected
> columns list in UPDATE to eliminate even the need to check whether
> related index needs to be updated instead of checking whether the
> values match
> * There _might_ be optimizations on Hibernate side that would help.
> I'd need to dive more into actual details as I'd rather expect that it
> would show up if we used Hibernate caching.
>
> Yet the performance might actually improve even more by using
> @DynamicUpdate annotation on JPA entities. The @DynamicUpdate would do
> the job the Column.updatable does, in a less-prohibitive way, still
> allowing the updates but only including the changed fields in the
> result UPDATE. I'd imagine that would be most beneficial on
> UserEntity.
>
> --Hynek
>
>
> On Mon, Sep 11, 2017 at 4:04 PM, Bill Burke <bburke at redhat.com> wrote:
>> This popped up in a support request, but we have a number of foreign
>> keys (with indexes) that are never changed, but yet are included in
>> update requests of those tables by Hibernate.  It seems that a number
>> of databases (and Hibernate, although don't know if there is a setting
>> for that) will not check to see if the old value equals new value.
>> This can cause concurrency issues (db deadlock).  I bet it is a big
>> performance issue too if indexes are updated as well.
>>
>> Should this be bumped to a priority for 3.4.1?  I'll create a JIRA if so.
>>
>> --
>> Bill Burke
>> Red Hat
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>> keycloak-dev at lists.jboss.org
>> https://lists.jboss.org/mailman/listinfo/keycloak-dev
>
>
>
> --
>
> --Hynek



-- 
Bill Burke
Red Hat