Hello:

We are running Arev 3.12.  We have a problem with one of our applications, it has dropped some rows.  They've just up an disappeared.  We have a small group trying to get a grip on where this might be happening.  One of our group is not an Arev person but is asking questions about the Linear Hashing and I don't know the answers.  I'm hopping someone can tell me where to get the answers.

Is Linear Hash a one way or two way hashing?  Is there any tools that we can use to interagate the files directly?  Such as determine where a missing row should have been stored, then look at the frame and if need be follow the over flow frames.  Where can we find the algorithm that Linear Hash uses?

One of our prongs of attach on this problem is to see if the missing data is actually still in the table or not.  Or where the row should be, if the key and/or row has been corrupted some how so that AREV can't find it.

Thanks,

Michael Slack

LHVerify picks up items incorrectly hashed. You can often force an incorrectly hashed record by editing the ID in LHDump.

But you are using the service .. so it isn't an 'arev' problem as such. Arev doesn't touch the data. The row is passed back from the service.

either programs or 'mfs' (any laying on those files?)

Which table is this? Is it used a lot (transactional?). Which of the systems?

There will be something 'related' with the data being 'lost'. I 'doubt' that it is corrupt data. If you can run lhverify against the data .. or even a simple 'select read' of all rows without error I doubt it is the data.

You could put an 'audit.mfs' on the file to audit DTUP (date, time, user, program) data written and delete.

There is an audit.mfs there.

dsig _at_ sigafoos.org.com onmouseover=window.status=the new revelation technology .. a refreshing change;return(true)"

David Tod Sigafoos ~ SigSolutions

Hello David:

Yes, we are using the Linear Hash service.  We are using AREV 3.12 on an MS 2003 network.  I wasn't aware that it was possible to run AREV without the Linear Hash running.

We are assuming that it's our application (programs) that are the cause of several rows going missing over the last several months but we are trying to cover all of our bases and not make any assumptions.  We have a small team trying to investigate this.  A couple are not AREV users or programmers or adminstrators but are very knowledgeable technically and they brought up the question about the Linear Hash.

We have an in house program to track personnel between our headquarters and our remote sites (in Antarctica).  Each leg of a persons travel is recorded.  Because we are using a National Guard group to fly to and from the continent and within the continent we also act as our own airline with manifesting people for trips and checking them onto flights.

It was discovered that 4 or 5 transport or flight records were missing.  This is the record of the flight's number, departure and destination locations and the date of the flight.  The associated flight information for each or the passengers was still in the proper rows in the other tables.  Upon further checking, it was found that about 75 transport or flight rows were missing.  We're still trying to pull the information together to investigate if these rows disapeared all at once or randomly over time.

Because the personel tracking application is used by such a small group in our company that no one table gets a lot of use to begin with.  From what I know of the application's guts, the transport table probably gets moderate to high usage relatively.  It's one of our key tables.  Without it we can't get people onto flights.

In our looking at the programs and processes, we've yet to find anything that jumps out at us as to the cause of this problem.  We've found some code that may not be the best practices but seems to get the job done.  So at this point we're assuming that some suttle combination of data and/or conditions is needed to cause our problem but we are still investigating.

The AUDIT.MFS, is that something you are suggesting we create or is it something we should already have?  I did a quick check and I couldn't find an AUDIT.MFS in our application.

Thank you for your time.

Michael Slack

I thought it was the travel routine .. i looked at that for a while with Caroline until we got pulled to something else. Oh my what a challenge you have before you.

Audit.Mfs was a routine that was delivered with the MFS book. Find the MFS book there and you can get the audit.mfs off of the disk. If you really can't find it let me know and I will get you a copy as I know you have a legal copy. Or contact RTI ..

you can install it on any file .. you can ADD looking at the return stack to see what program called it .. add that to the MFS.

Also with the service I beleive that there is a log you can build and evaluate for any problems. I really doubt it is your service but .. you are right in ruling everything out.

Let me know if you need anything ..

dsig _at_ sigafoos.org.com onmouseover=window.status=the new revelation technology .. a refreshing change;return(true)"

David Tod Sigafoos ~ SigSolutions

http://www.revelation.com/__85256DB80017688B.nsf/0/89D53E0B061C9193852563E00054A986?OpenDocument

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