I am in the process of creating a custom historian module for ignition 8.3. I am seeing a strange issue when reading data from an instance of my custom historian. When adding multiple tags to a power chart, the colors/values for the tags flip flop back and forth. One second the first tag will be green and the other orange, and the next second the first tag will be orange and the second green. It flip flops back and forth randomly. The values at the bottom also switch. Ignitions seems to call the doQueryAggregated method in my AbstractQueryEngine implementation once for each tag, so I am not sure what I could be doing incorrectly. Has anyone else run into this behavior?
This sounds like a bug that was fixed in 8.3.3 (currently in RC). The issue was in the underlying query infrastructure that custom historian implementations also go through. Column ordering wasn't being preserved during query processing, which caused column headers to get mismatched with the actual data when querying multiple tags.
If you're on 8.3.2 or earlier, upgrading to 8.3.3 should resolve this.
Looks like that was my problem. Thanks! Unfortunately I am still having another issue that I thought may be related. I can set the pointCount to -1 and successfully get raw data to show on the power chart for one tag. But if I add multiple tags with the pointCount set to -1 the tags disappear and no data is shown. Is this an issue you have seen? The calls to get raw data from my module are still being made. I have stepped through the debugger and everything seems to be executing as I would expect. There are no errors in the logs
