A complete census of the population was conducted in 2016, and will be done again in 2021. The 2006 survey was a post-census survey, meaning that a sample of official languages minorities was drawn from the 2006 census.
Still, it was a sample, and the questionnaire was very long. It took 45 minutes to complete. It really had to be done with just a sample and not the entire population.
However, the Elementary-Secondary Education Survey collects administrative data annually and is based on a complete census of all youth enrolled in schools in Canada.