[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-3011) merge() optimization for Oracle dialect

[MG (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-3011?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_29161 ] 

MG commented on HHH-3011:
-------------------------

It needs to know whether object was saved or not before. So it is not equivalent.
I need to pass detached object (hibernate doesn't know anything about it), and do insert or update without 2 trips to database (without extra select).
I do not believe it is possible in current hibernate implementation. However this is very common ETL pattern.



> merge() optimization for Oracle dialect
> ---------------------------------------
>
>                 Key: HHH-3011
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-3011
>             Project: Hibernate3
>          Issue Type: Improvement
>          Components: core
>            Reporter: MG
>            Priority: Minor
>
> merge() optimization for Oracle dialect.
> Since 9i Oracle has a MERGE statement which is very useful to save round trips to database in merge() call
> which will make dramatic improvement for performance  of loading large row sets.
> MERGE command processes the conditional INSERT-or-UPDATE within a single statement.
> So instead of doing 'select' first to detect whether entity is in database or not (This is one round trip to DB)
> and then issuing 'update' or 'insert' all of it could be done in one statement with no extra round trips using oracle SQL MERGE statement.
> http://www.oracle.com/technology/products/oracle9i/daily/Aug24.html

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