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From "Yip Ng" <yipng...@gmail.com>
Subject Re: Question on nested transaction and SPS recompilation, anyone?
Date Wed, 09 Aug 2006 21:30:46 GMT
3)  Even though the nested transaction has committed but since the parent
transaction is rollback, shouldn't the change in the nested transaction
rollback as well?  This is not what
I am seeing with the example given in 2).


On 8/9/06, Yip Ng <yipng168@gmail.com> wrote:
>
> Hi
>
>    I am working on a jira issue (DERBY-1621) and I am hoping to get some
> clarifications from
> someone who is familar with the recompilation phase of a stored prepard
> statement(SPS) logic.
>
>    If a SPS needs to be recompiled during execution, SPSDescriptor
> getPreparedStatement()
> first updates the SYS.SYSDEPENDS system table with the current
> transaction.  Then it
> attempts to get a user nested transaction(if it can) when updating the
> SYS.SYSSTATEMENTS
> system table, then commits the user nested transaction.
>
> 1) Why isn't the SPS recompilation using the same transaction to update
> SYS.SYSDEPENDS and
>     SYS.SYSSTATEMENTS?  Is this for a concurrency enhancement?
>
> 2) Wouldn't this cause a problem for the dependency manager to lose stored
> dependencies
>    if the parent transaction is rollback due to a constraint violation?
> i.e.:
>
>    create table t1 (i int);
>    create table t2 (i int);
>    create trigger tt after insert on t1 for each statement mode db2sql
> insert into t2 values 1;
>    insert into t1 values 1;
>    create unique index tu on t2(i);
>    insert into t1 values 1;
>
>    insert into t1 values 1 will fail due to unique constraint violation
> from the trigger action, but now the SPS is marked as valid and the stored
> dependencies are lost due to the parent transaction rollback.  So the SPS
> will not get invalidated later if a drop index tu was issued because the
> conglomerate tu does not have the SPS as one of its dependents.
>
>
>

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