[Jpox-issues] [JPOX JIRA] Updated: (RDBMS-36) Retrieval of object using new-table inheritance does one SELECT for each table in the inheritance tree when should do single SELECT for all fields

[Andy J. (JIRA) <web...@jp...>]

     [ http://www.jpox.org/servlet/jira/browse/RDBMS-36?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Andy Jefferson updated RDBMS-36:
--------------------------------

              Summary: Retrieval of object using new-table inheritance does one SELECT for each table in the inheritance tree when should do single SELECT for all fields  (was: Retrieval of object using new-table inheritance does one SELECT for each table in the inheritance tree)
    Affects Version/s: 1.2.0-rc-1

> Retrieval of object using new-table inheritance does one SELECT for each table in the inheritance tree when should do single SELECT for all fields
> --------------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: RDBMS-36
>                 URL: http://www.jpox.org/servlet/jira/browse/RDBMS-36
>             Project: RDBMS
>          Issue Type: Improvement
>          Components: ORM
>            Reporter: Andy Jefferson
>         Assigned To: Andy Jefferson
>             Fix For: 1.2.0-rc-1
>
>
> When we have an inheritance hierarchy like this
> class A { ... } // new-table
> class B extends A { ... } // new-table
> class C extends B { ... } // new-table
> and we do pm.getObjectById(id) this does
> SELECT ... (discrim/JPOXMETADATA) ... 
> to determine the inheritance level of the object, followed by its migration HOLLOW -> PCLEAN
> 14:53:57,493 (main) DEBUG [JPOX.Lifecycle] - Object "org.jpox.test.FSub1Sub@2f0df1" (id="6[OID]org.jpox.test.FSub1Sub") has a lifecycle change : "HOLLOW"
> ->"P_CLEAN"
> 14:53:57,493 (main) DEBUG [JPOX.Persistence] - Object "org.jpox.test.FSub1Sub@2f0df1" having fields "id,name,revision" fetched from table "`FBASE`"
> 14:53:57,494 (main) DEBUG [JPOX.Datastore.Retrieve] - SELECT THIS.`ID`,THIS.`NAME`,THIS.`REVISION` FROM `FBASE` THIS WHERE (THIS.`FBASE_ID`=<6>)
> 14:53:57,494 (main) DEBUG [JPOX.Datastore.Retrieve] - Execution Time = 0 ms
> 14:53:57,495 (main) DEBUG [JPOX.Persistence] - Object "org.jpox.test.FSub1Sub@2f0df1" having fields "description,value" fetched from table "`FSUB1`"
> 14:53:57,495 (main) DEBUG [JPOX.Datastore.Retrieve] - SELECT THIS.`DESCRIPTION` FROM `FSUB1` THIS WHERE (THIS.`FSUB1_ID`=<6>)
> 14:53:57,496 (main) DEBUG [JPOX.Datastore.Retrieve] - Execution Time = 0 ms
> 14:53:57,496 (main) DEBUG [JPOX.Persistence] - Object "org.jpox.test.FSub1Sub@2f0df1" having fields "value" fetched from table "`FSUB1SUB`"
> 14:53:57,496 (main) DEBUG [JPOX.Datastore.Retrieve] - SELECT THIS.`VALUE` FROM `FSUB1SUB` THIS WHERE (THIS.`FSUB1SUB_ID`=<6>)
> 14:53:57,497 (main) DEBUG [JPOX.Datastore.Retrieve] - Execution Time = 1 ms
> so it does a SELECT for each of the tables that it is stored in. This could be merged into
> SELECT THIS.`ID`,THIS.`NAME`,THIS.`REVISION`, SUB1.`DESCRIPTION`, SUB2.`VALUE`
> FROM `FBASE` THIS 
> INNER JOIN `FSUB1` SUB1 ON THIS.`ID` = SUB1.`FSUB1_ID`
> INNER JOIN `FSUB2` SUB2 ON THIS.`ID` = SUB2.`FSUB2_ID`
> WHERE (THIS.`FBASE_ID`=<6>)

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