blob: can bolt support read/write blob data

[vipally]

Current data access API assume all data is in memory func (b *Bucket) Put(key []byte, value []byte) error func (b *Bucket) Get(key []byte) []byte

Compare with other embeded db (like sqlite, berkerlydb), read/write blob( maybe larger than 4GB) is a common demand. I hope bolt can add APIs to open blob tx.

[simar7]

I'm also interested in knowing if there is any interest in this.