[teiid-issues] [JBoss JIRA] Closed: (TEIID-897) Create a new autowrap mode to replace pessimistic/optimistic

[Steve Hawkins (JIRA)]

     [ https://jira.jboss.org/browse/TEIID-897?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Steve Hawkins closed TEIID-897.
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> Create a new autowrap mode to replace pessimistic/optimistic
> ------------------------------------------------------------
>
>                 Key: TEIID-897
>                 URL: https://jira.jboss.org/browse/TEIID-897
>             Project: Teiid
>          Issue Type: Feature Request
>          Components: Query Engine
>    Affects Versions: 7.0
>            Reporter: Steven Hawkins
>            Assignee: Steven Hawkins
>             Fix For: 7.0
>
>
> There are issues with pessimistic/optimistic autowrap modes:
> 1. optimistic transaction autowrap is no longer needed since all installations of Teiid have a transaction manager available.  This mode is really only useful as a development time aid - there is also a case to replace it with a readonly mode to prevent all updates.
> 2. the detection of when a transaction is needed is based upon the resolved from of a command and not the actual plan/execution.  This has led to progressively more pessimistic logic to capture when a transaction is needed (being fully pessimistic we'd have to assume that any procedure with an update count of 1 also needs a transaction since an error can occur during the conversion of output parameters that should cause a rollback).  We should either do a better job based upon the plan/execution, or just state simple assumptions (select -no txn, source insert, update, delete, exec w/ update count <=1 -no txn, else txn).
> 3. the terminology is confusing since it's evocative of locking semantics
> I therefore propose we change these to txnAutoWrap=AUTO, which would be similar to pessimistic mode and would change the detection strategy to one of the proposals from 2.
> We should also be explicit that this mode is based upon the assumption that multiple selects do not need to be grouped in the same transaction.  However when there is a transaction, then the selects will be performed in the same transaction.

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