andreivisan/pyminikv

File system key/value distributed DB built with Python

SIMPLE DISTRIBUTED DATABASE SERVER

Requirements

1. Database server under 1000 lines of code

2. Key/Value support

3. Distributed DB server using uwsgi

4. Initial build in Python - future build in Go to improve performance

5. Server will respond to following commands

   • GET
   • SET
   • DELETE
   • FLUSH
   • MGET ...
   • MSET ...

6. Supported data types

   • Strings and Binary Data
   • Numbers
   • NULL
   • Arrays (which may be nested)
   • Dictionaries (which may be nested)
   • Error messages

7. Initially stored in memory - future in the file system

Architecture

• Master volume will keep track of the stored keys
• Child volumes will store the actual data

Redis protocol for communication

Data-Type	Prefix	Structure	Example
Simple String	+	+{string data}\r\n	+this is a simple string\r\n
Error	-	-{error message}\r\n	-ERR unknown command "FLUHS"\r\n
Integer	:	:{the number}\r\n	:1337\r\n
Binary	$	${number of bytes}\r\n{data}\r\n	$6\r\n foobar\r\n
Array	*	*{number of elements}\r\n{0 or more of above}\r\n	*3\r\n +a simple string element\r\n :12345\r\n $7\r\n testing\r\n
Dictionary	%	%{number of keys}\r\n{0 or more of above}\r\n	%3\r\n +key1\r\n +value1\r\n +key2\r\n *2\r\n 1 +value2-0\r\n +value2-1\r\n :3\r\n $7\r\n testing\r\n
NULL	$	$-1\r\n (string of length -1)	$-1\r\n