Can one store different size records in LMDB or do they need to be in the exact same size?

Question

I like to record my images in different sizes in LMDB dataset. Is it viable to store these images without resizing into certain size? If it is, then do I lose any space by the gap of the largest possible record in LMDB? So for instance, if the largest file in LMDB is 1MB then each record allocates 1MB even the real record size is smaller than this.

Answer 1

Yes you can store differently sized values in lmdb. The maximum space you can loose is determined by the pagesize and not your maximum value size. The default pagesize is 4096 bytes (you have to recompile to change it), so worst case the db is about double the size of your actual data (if all your values would be the same and a little more than half the pagesize).