Dump records from redis into mongodb.
The records will be written to mongodb ASAP, callers should control the frequency of writing.

The format of the record is defined as :
key(tablname:record_id) -> value(packed with msgpack, optional snappy compression)

• REDIS_HOST : eg: 127.0.0.1:6379
• MONGODB_URL : eg: mongodb://172.17.42.1/mydb
• NSQD_HOST : eg: http://172.17.42.1:4151
• ENABLE_SNAPPY: eg: true

install gpm, gvp first
$go get -u https://github.com/gonet2/bgsave/
$cd bgsave
$source gvp
$gpm
$go install bgsave

#install with docker docker build -t bgsave .