lastcanal

Then they'd need some very powerful mining equipment! Bitcoin uses merkel trees to ensure transactions in blocks never change.

OVH has a big datacenter outside Montreal.

http://www.ovh.com/ca/en/vps/

It uses LevelDB as the storage engine and lets you configure the cache parameters from the configuration file.

   leveldb:
	# in MB
	cache_size: 500
	# in KB
	block_size: 32
	# in MB
	write_buffer_size: 64
	# in MB
	compaction_speed: 1000
	# yes|no
	compression: no

I don't have any production experience with it, but I did load the entire Bitcoin Testnet blockchain into it without issue. In Redis the same dataset required ~6 gigs of RAM.

The major advantage (depending on your use case) is that your dataset is not limited to the size of your available memory.

Take a look at Lamernews (https://github.com/antirez/lamernews). It is written in Ruby by the author Redis. It uses Redis as the primary database.

Here is it in action: http://lamernews.com/