Re: [ledgersmb-devel] Which corrective action for "invoice COGS schema check"?

Hi,

After having merged the infrastructure to check data validity in an existing database before applying an upgrade script, I'm reviewing existing scripts to see if they may qualify to be enhanced with a check and user intervention.

One script which qualifies is 1.5/invoice-tbl-cogs-constraint.sql which adds a constraint verifying that the COGS routines post data which makes sense.

Existing data does not necessarily comply with the new constraint. I wonder though what corrective action to offer a user who is the proud owner of non-compliant data. I see a number of options:

1. Tell the user to contact the mailing list (and block his migration in the mean time)

That may be necessary if other things fail anyway.

Sure, but it's not the best way to bind people to our software and community in the sense that if we want to inspire confidence and awe, asking them to contact us to "unfiddle" their data might not be a move we want to resort to. (But it *is* an option.)

2. Modify the data to be within the bounds to be enforced (and thereby loose the COGS audit trail?

Modifying data is of course dangerous. The question here is what we mean by modifying the data. Are we talking about deleting data? or some other modifications?

Modifying data in the sense that the value of the "allocated" field falls outside the boundaries of what's allowed, reducing (or increasing) the number in such a way that it's within bounds again will allow us to apply the constraint. It won't change the COGS values already posted, but I'm not sure that such modifications will result in the same values being posted going forward (as without the modifications). Maybe you can confirm that changing the 'allocated' amount on "saturated" purchase invoices will (or won't) change the outcome for newer COGS calculations?

3. Allow constraint creation to fail by modifying Loadorder and create a new script which creates a "not valid" constraint (which allows the existing data to remain in place, but verifies new data)

You could also create a constraint that checks if data is old and passes it too.

Ok. But what criterion determines that "data is old"?

4. Create a check script which creates the "not valid" constraint and fakes script application by modifying dbchanges tables

I don't see what this gets us.

I was thinking this is the "cheap" (or rather: "easy on the programmer") version of "data is old"; it doesn't require us to recalculate anything, it simply allows us to apply the constraint. New data will be just as safely protected as on any other database, but old data won't need to change.

5. Adjust the data back into bounds, allocating the overage to more recent invoices and creating a COGS adjustment journal which the admin must post

This would get my vote.

Ok. I'm thinking such a procedure would work as follows:

1. A query determines the violating rows

2. For each row, the delinquent amount (overage) is calculated and with it, the COGS amount (money) to be reversed

3. For each delinquent amount (overage), the COGS calculation routines calculate the new cost to be posted, based on available FIFO amounts

4. The user is presented with a GL transaction, to be posted on the migration date (or another, selectable, posting date)

5. The user elects to proceed, causing the proposed GL transaction to be posted.

I'm now running into an issue though: our COGS routines destructively modify existing data. This means that in order to propose the GL transaction above (and calling the COGS routines), there's no way *not* to accept the posted transaction (because the underlying data has already been destructively modified to include that transaction).

Which solutions do we have here? I'm seeing basically just one option:

1. Calculate the full transaction, post it and *inform* the user of the posted data, instead of asking for their permission.

This step has the huge downside that the user doesn't get to choose on which date the correction journal gets posted. Any other options?

Bye,

Erik.

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