Best data length for storing OAuth tokens

I want to write a mysql database schema for storing OAuth access tokens which is sufficiently generic so that it is capable for supporting any provider that complies with the OAuth standard.

What would be a sensible data length to achieve this aim and why? As far as I can see, no maximum length is enforced by the standard and开发者_如何学Go I don't want to have to change my column length whenever I decide to support a new provider that happens to use larger tokens.

If this is not practical/possible, what would be a sensible length for supporting the more popular OAuth providers and why?

CHOSEN SOLUTION

Using a data type with an undefined length seems to be the only sufficiently generic option for my case.

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You can use text data type for this if you don't know the exact length.