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SimpleJob DA transactions

Christopher_Meyer

I'd like to use a SimpleJob DA to defer some tasks, but have concerns with how database transactions are handled. It seems the agent first opens a database transaction, calls Map(), and commits the transaction regardless if an error occurred in Map(). This could lead to data corruption if Map() contained multiple database changes and only some of them were committed.

Am I missing something, or is this a known issue or limitation with SimpleJob DAs?

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David Templeton

Chris

If the task returns ok = FALSE then the transaction will be aborted, BUT there is also that within your task you should have a transaction and if that is rolled back it is rolled back to level zero so long as you are using dbConnect.StartTrans() [dbConnect = prgCtx.fDBConnect]. And not CAPI.StartTransaction, which should not be used by solution anyways.

David

Christopher_Meyer

Hi David,

Unfortunately, that's not the behaviour I see. Even if I wrap my Map() function in a transaction, do a rollback, and return an error Assoc, the outer most transaction still does a commit.

Take the following as an example to rename a node by its DataID. I purposely set results.ok = false, roll back the transaction, and return the error assoc. Despite doing this the node still gets renamed:

function Assoc Map()    Object prgCtx = .fPrgCtx    Integer DataID = .fTaskData.DataID    String newName = .fTaskData.NewName    Assoc results    results.ok = true    if prgCtx.fDBConnect.StartTrans()        DAPINODE node = DAPI.GetNodeByID(.fPrgCtx.DapiSess(), DAPI.BY_DATAID, DataID)        if IsNotError(node)            Object llnode = $LLIApi.LLNodeSubsystem.GetItem(node.pSubtype)            results = llnode.NodeRename(node, newName)        end        // here we pretend something went wrong...        results.ok = false        prgCtx.fDBConnect.EndTrans(results.ok)    end    return resultsend

To queue the task:

Assoc taskDatataskData.DataID = 2000taskDAta.NewName = "Enterprise - Testing""$DistributedAgent.MapReducePkg.Map(prgCtx, "MyRenameDA", taskData)

Christopher_Meyer

Hi David,

To follow up:

BUT there is also that within your task you should have a transaction and if that is rolled back it is rolled back to level zero so long as you are using dbConnect.StartTrans()

What do you mean it gets rolled back to level zero? Doesn't dbConnect.EndTrans(false) just pop one transaction off the transaction stack?

I know there is a dbConnect.ResetTransactionsIfNecessary() to roll back all open transactions, but I don't think that's what you're referring to here.

Thanks