Use BYTEA SQLite type in wrapper crate

[ceyhunsen]

Proposal Description

Almost every database wrapper converts Rust native type to string and writes it to database that way. This is both slow and uses too much storage. Instead, use BYTEA type and write datas in bytes.

Example impl:

#[derive(Serialize, Deserialize, sqlx::FromRow, Debug, Clone)]
pub struct SignatureDB(pub secp256k1::schnorr::Signature);

impl sqlx::Type<sqlx::Postgres> for SignatureDB {
    fn type_info() -> sqlx::postgres::PgTypeInfo {
        sqlx::postgres::PgTypeInfo::with_name("BYTEA")
    }
}
impl Encode<'_, Postgres> for SignatureDB {
    fn encode_by_ref(&self, buf: &mut PgArgumentBuffer) -> sqlx::encode::IsNull {
        let serialized = self.0.serialize().to_vec();
        <Vec<u8> as Encode<Postgres>>::encode_by_ref(&serialized, buf)
    }
}
impl<'r> Decode<'r, Postgres> for SignatureDB {
    fn decode(value: PgValueRef<'r>) -> Result<Self, sqlx::error::BoxDynError> {
        let s = <Vec<u8> as Decode<Postgres>>::decode(value)?;
        let x: secp256k1::schnorr::Signature = secp256k1::schnorr::Signature::from_slice(&s)?;
        Ok(SignatureDB(x))
    }
}