What version of PI Data Archive are you using?
Unfortunately out of the box there is no easy way to know which tags were modified. There is an internal work item for the Archive File Header to keep track of the last modified record number, in which case this would be easy to track down. This, however, has not yet been implemented.
One fairly straightforward method you could try is searching the message logs for connections (or even potentially failed writes) that are created around the time of the last modified times. Perhaps if a specific application connects right before the modified times, this might lead us in the right direction.
A few other things that are interesting, is that the modified times look different for each archive, so I agree this does not look like a recalculation or scheduled task that is the culprit in this case. (except that 4/24 and 4/25 are both right around 1:09 - difficult to say if this is coincidence or not). They also do not look to update frequently, so my best guess is that this looks to be a manual entry type application that might be making these changes.
There is a way for us to better track which tags are updated by configuring ProcMon to trace file activity on an archive file, however, we would need to wait for the issue to reoccur in order to get meaningful information and this would not help for a past occurrence of the issue. If you would like assistance with using this method I can create a technical support case and we can go through the steps to do this.
The issue seems to be ongoing and our archives shift every 5/6 days so getting a repeat event won’t take long.
I’ve looked through the logs but there doesn’t seem to be anything that links to the times I’m getting for the updates. The culprit I was pinning things on is logged out a couple of minutes before the archive last modified timestamp, so I don’t know if that’s a PI timing issue in that it takes a couple of minutes for manually uploaded tags to register in the historical archives.
If you could raise a support ticket, then we can try the ProcMon approach to see what is actually going on.
Senior Process Control Specialist
Cristal Pigments UK
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We have a program that runs daily to query the Data Archive using PI SQL... We retrieve most of the information available via PI SMT or PI builder and save a summary of the changed information in SQL as an audit function for the enterprise....
The important point is the last modified field is available via PI SQL... I would look up the actual command, but am about to board an airplane and will be traveling the rest of the day... Hopefully this will help.
If you could share how you have done this that would great. I’ve not used PI SQL so a bit of a dummies guide on what to do would be helpful.
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There are several OSISoft training videos showing how to use PI SQL Commander Lite to query the PI database. It does require installing the PI OLEDB Provider.
Launch PI SQL Commander Lite
Connect to a PI server
Open a New Query Window
Paste the query below to retrieve selected information for PI tags that have changed configuration in the past 30 days.
SELECT tag, descriptor, pointType, changeDate
WHERE changeDate >= 't-30d'
ORDER BY tag
To be clear, using an OLEDB solution like this will only tell you which tags have had a configuration change. What is being captured in the archive modified time updates are changes/updates to data that are recorded in the archive. If you want to capture data changes you will have to do some manual comparison to know what is changing and when.