I get that there is a cost incurred when I use YouTube API service, but what I would like to know is if the cost is per request or not. For example, when I query the meta data of 3 videos, would the cost be tripled for that one request, or would the cost be the same as if I query the meta data for 1 video?
I assume you talk about the quota with the YouTube API v3, i can suggest you to visit this link, a quota calculator:
This tool lets you estimate the quota cost for an API query. All API requests, including invalid requests, incur a quota cost of at least one point.
https://developers.google.com/youtube/v3/determine_quota_cost COST 3
- would the cost be tripled for that one request, or would the cost be the same as if I query the meta data for 1 video?
We can assume "cost be the same as if I query the meta data for 1 video" because they speaks about "request" like this :
The request for multiple videos is like this :
- GET https://www.googleapis.com/youtube/v3/videos?part=snippet&id=zMbIipvQL0c%2CLOcKckBLouM&key={YOUR_API_KEY}
Which is also one request, so it's also a cost of 3 !
The real deal is when you have multiple pages:
Note: If your application calls a method, such as search.list, that returns multiple pages of results, each request to retrieve an additional page of results will incur the estimated quota cost.
来源：https://stackoverflow.com/questions/35557705/youtube-data-api-cost-per-request-or-per-object