Unable to query raw data for multiple tags in custom historian module

Module Development
1

I am working on a custom historian module on ignition 8.3.4. When using my module, querying for multiple tags in a powerchart with aggregate calls works fine. Querying for raw data with the pointCount set to -1 for a single tag also works. But when I add a second tag to the powerchart it displays no data. I have stepped throught the debugger and everything seems to be executing as I would expect. Has anyone else seen this issue? There are no errors in the logs. I have turned on debug and I can see that the expected number of rows were written for 2 tags logging at 1 value per second for a one minute interval

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2

Are you able to share any actual code?

It's going to be hard to provide concrete advice in a vacuum.

3

Thanks for the reply. I have written some simple test code that reproduces my issue. The code overrides the doQueryRaw method in AbstractQueryEngine and returns random values for each second in the time range and for each query key given.

@Override
protected Optional<Integer> doQueryRaw(RawQueryOptions rawQueryOptions, RawPointProcessor rawPointProcessor)
{
	DefaultProcessingContext.Builder<RawQueryKey, DataPointType> contextBuilder = DefaultProcessingContext.builder();
	rawPointProcessor.onInitialize(contextBuilder.build());

	Date startDate = Date.from(rawQueryOptions.getTimeRange().get().startTime());
	Date endDate = Date.from(rawQueryOptions.getTimeRange().get().endTime());
	int count = 0;
	for (var queryKey : rawQueryOptions.getQueryKeys()) {
		Random random = new Random();
		for (long t = startDate.getTime(); t <= endDate.getTime(); t += 1000) {
			Date current = new Date(t);
			int value = random.nextInt(100);

			rawPointProcessor.onPointAvailable(queryKey, DataPointFactory.createAtomicPoint(value, QualityCode.Good, current.toInstant(), queryKey.source()));
			count++;
		}
	}

	rawPointProcessor.onComplete();
	return Optional.of(count);
}

Adding one tag to a powerchart with pointCount set to -1 returns the data.

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When I add a second tag, the chart goes blank.

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4

@paul-griffith Have you had a chance to review the code I posted to reproduce this issue?

5

Nope. Historian isn't my area, so I'll have to tag someone else in to review - not sure when they'll be able to.

For the sake of it, can you try on the 8.3.5 nightly/RC? There were other issues with historian data processing fixed. I don't have any real reason to think they're the root cause of what you're facing, but it's worth a shot.