I do think the parent thinks that. But it's simply not true based on my research. COUNT(*) doesn't need any actual data from the rows, so I'm wondering if there's something else.

First result in Google confirms that at least for Postgres: https://www.citusdata.com/blog/2016/10/12/count-performance/

Another one from stackoverflow: https://stackoverflow.com/questions/2710621/count-vs-count1-... with a citation:

> Don't be fooled by those advising that when using * in COUNT, it fetches entire row from your table, saying that * is slow. The * on SELECT COUNT(*) and SELECT * has no bearing to each other, they are entirely different thing, they just share a common token, i.e. *.