FIXME: Remove or refine this function, as it is not general.

TODO: Better to be a streaming interface.

GenerateBinaryPlan generate visual plan from raw data.

TODO: Better to be a streaming interface.

GetTiDBConnection gets the TiDB connection stored in the gin context by `MWConnectTiDB` middleware.

MWConnectTiDB creates a middleware that attaches TiDB connection to the context, according to the identity information attached in the context.

NewJWTString create a JWT string by given data, expire in 24 hours.

ParseJWTString parse the JWT string and return the raw data.

TakeTiDBConnection takes out the TiDB connection stored in the gin context by `MWConnectTiDB` middleware.

role tag.

The key that attached the SessionUser in the gin Context.

Claims is a struct that will be encoded to a JWT.

The content of this structure will be encrypted and stored as both Session Token and Sharing Token.