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https://issues.apache.org/jira/browse/CAY-1927?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Andrus Adamchik updated CAY-1927:
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Fix Version/s: (was: 4.0.M3)
Short term future
> Use deferred constraint checking on the databases that support it
> -----------------------------------------------------------------
>
> Key: CAY-1927
> URL: https://issues.apache.org/jira/browse/CAY-1927
> Project: Cayenne
> Issue Type: Task
> Reporter: Andrus Adamchik
> Assignee: Andrus Adamchik
> Fix For: Short term future
>
>
> There's an ongoing issue of operation sorting on commit not handling all
> possible cases (e.g. see CAY-1410). We can solve it by ignoring sorting in
> Cayenne and instead relying on deferred constraints checking in the database.
> Not all databases support it. But there are few that do:
> Oracle:
> http://docs.oracle.com/cd/B28359_01/server.111/b28286/statements_10003.htm#SQLRF55300
> PostgreSQL: http://www.postgresql.org/docs/9.1/static/sql-set-constraints.html
> MySQL: (no support)
> Derby: (no support)
> SQLServer: (no support)
> The way I see the implementation is this:
> 1. Define a stack property in org.apache.cayenne.configuration.Constants that
> turns deferred constraint checking on and off:
> String SERVER_DEFERRED_CONSTRAINTS_PROPERTY =
> "cayenne.server.deferred_constraints";
> Default will be "false".
> 2. The property may be checked by DbAdapter when executing BatchAction. If
> the property is "true" and concrete DbAdapter supports deferred constraint
> checking, it will generate and execute SQL to instruct the DB to use it.
> (3.) Ideally we should also save ourselves some CPU cycles by not invoking
> EntitySorter inside DataDomain on commit. EntitySorter main purpose is to
> insert rows in such order that FK constraints are immediately satisfied (and
> deficiencies in the sorting alg. are the biggest motivation for this
> feature). However this might be tricky for two reasons:
> * EntitySorter is invoked in a higher framework layer before the queries are
> split by DataNode. So it will have to prematurely check which DataNode is
> involved for each entity in commit, to see if deferred constraints are
> supported.
> * Aside from FK constraint checking it provides the ordering that ensure
> auto-incremented PK values are available to related FKs.
> So we may have to keep the sorter around until we figure out how to handle
> the stuff above.
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