Does queryGranularity in IngestionSpec aggregates according to ingestion time or tick of hour

If i specify a queryGranularity like “PT15M”, does that mean the data is aggregated:

  1. with respect to tick of hour, ie aggregated at 03:00, 03:15, 03:30…
  2. with respect to whenever KIS indexing task starts, eg say task starts at 03:02, so aggregated at 03:17, 03:32…

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