[redis.git] / TODO

Redis TODO and Roadmap

VERSION 1.2 TODO (Zsets, Integer encoding, Append only journal)
===============================================================

Most of the features already implemented for this release. The following is a list of the missing things in order to release the first beta tar.gz:

* Continue adding tests accordingly to gcov output.

VERSION 1.4 TODO (Hash type)
============================

* Blocking LPOP (BLPOP).
* Hashes (HSET, HGET, HEXISTS, HLEN, ...).
* List ops like L/RPUSH L/RPOP should return the new list length.

VERSION 1.6 TODO (Virtual memory)
=================================

* Redis Virtual Memory for datasets bigger than RAM (http://groups.google.com/group/redis-db/msg/752997c7b38553cd)

VERSION 1.8 TODO (Fault tollerant sharding)
===========================================

* Redis-cluster, a fast intermediate layer (proxy) that implements consistent hashing and fault tollerant nodes handling.

Interesting readings about this:

    - http://ayende.com/Blog/archive/2009/04/06/designing-rhino-dht-a-fault-tolerant-dynamically-distributed-hash.aspx

VERSION 2.0 TODO (Optimizations and latency)
============================================

* Lower the CPU usage.
* Lower the RAM usage everywhere possible.
* Use epool and alike to rewrite ae.c for Linux and other platforms suppporting fater-than-select() mutiplexing APIs.
* Implement an UDP interface for low-latency GET/SET operations.

VERSION 2.2 TODO (Optimizations and latency)
============================================

* JSON command able to access data serialized in JSON format. For instance if I've a key foobar with a json object I can alter the "name" file using somthing like: "JSON SET foobar name Kevin". We should have GET and INCRBY as well.

OTHER IMPORTANT THINGS THAT WILL BE ADDED BUT I'M NOT SURE WHEN
===============================================================

BIG ONES:

* Specially encoded memory-saving integer sets.
* A command to export a JSON dump (there should be mostly working patch needing major reworking).

SMALL ONES:

* Give errors when incrementing a key that does not look like an integer, when providing as a sorted set score something can't be parsed as a double, and so forth.
* MSADD (n keys) (n values). See this thread in the Redis google group: http://groups.google.com/group/redis-db/browse_thread/thread/e766d84eb375cd41

SHORT/LONG TERM RANDOM TODO ITEMS
=================================

Most of this can be seen just as proposals, the fact they are in this list
it's not a guarantee they'll ever get implemented ;)

* Move dict.c from hash table to skip list, in order to avoid the blocking resize operation needed for the hash table.
* FORK command (fork()s executing the commands received by the current
  client in the new process). Hint: large SORTs can use more cores,
  copy-on-write will avoid memory problems.
* DUP command? DUP srckey dstkey, creates an exact clone of srckey value in dstkey.
* SORT: Don't copy the list into a vector when BY argument is constant.
* Write the hash table size of every db in the dump, so that Redis can resize the hash table just one time when loading a big DB.
* LOCK / TRYLOCK / UNLOCK as described many times in the google group
* Replication automated tests
* Byte Array type (BA prefixed commands): BASETBIT BAGETBIT BASETU8 U16 U32 U64 S8 S16 S32 S64, ability to atomically INCRBY all the base types. BARANGE to get a range of bytes as a bulk value, BASETRANGE to set a range of bytes.
* zmalloc() should avoid to add a private header for archs where there is some other kind of libc-specific way to get the size of a malloced block. Already done for Mac OS X.
* Read-only mode.
* Pattern-matching replication.
* Don't save empty lists / sets / zsets on disk with snapshotting.
* Remove keys when a list / set / zset reaches length of 0.
* Add an option to relax the delete-expiring-keys-on-write semantic *denying* replication and AOF when this is on? Can be handy sometimes, when using Redis for non persistent state, but can create problems. For instance should rename and move also "move" the timeouts? How does this affect other commands?

DOCUMENTATION WISHLIST
======================

* Page explaining tips to reduce memory usage.
* A Sorted sets HOWTO
Commit	Line	Data
f284d963	1	Redis TODO and Roadmap
f284d963	2
2014c437	3	VERSION 1.2 TODO (Zsets, Integer encoding, Append only journal)
c35f7d5b	4	===============================================================
	5
	6	Most of the features already implemented for this release. The following is a list of the missing things in order to release the first beta tar.gz:
f6b141c5	7
163f4b8c	8	* Continue adding tests accordingly to gcov output.
23cff1a8	9
2014c437	10	VERSION 1.4 TODO (Hash type)
c35f7d5b	11	============================
23cff1a8	12
3f477979	13	* Blocking LPOP (BLPOP).
23cff1a8	14	* Hashes (HSET, HGET, HEXISTS, HLEN, ...).
09f6f702	15	* List ops like L/RPUSH L/RPOP should return the new list length.
f6b141c5	16
2014c437	17	VERSION 1.6 TODO (Virtual memory)
c35f7d5b	18	=================================
7d65b33d	19
	20	* Redis Virtual Memory for datasets bigger than RAM (http://groups.google.com/group/redis-db/msg/752997c7b38553cd)
	21
2014c437	22	VERSION 1.8 TODO (Fault tollerant sharding)
c35f7d5b	23	===========================================
7d65b33d	24
c35f7d5b	25	* Redis-cluster, a fast intermediate layer (proxy) that implements consistent hashing and fault tollerant nodes handling.
7d65b33d	26
5b2a1c29	27	Interesting readings about this:
	28
	29	- http://ayende.com/Blog/archive/2009/04/06/designing-rhino-dht-a-fault-tolerant-dynamically-distributed-hash.aspx
	30
2014c437	31	VERSION 2.0 TODO (Optimizations and latency)
c35f7d5b	32	============================================
7d65b33d	33
	34	* Lower the CPU usage.
	35	* Lower the RAM usage everywhere possible.
	36	* Use epool and alike to rewrite ae.c for Linux and other platforms suppporting fater-than-select() mutiplexing APIs.
	37	* Implement an UDP interface for low-latency GET/SET operations.
	38
2014c437	39	VERSION 2.2 TODO (Optimizations and latency)
	40	============================================
	41
	42	* JSON command able to access data serialized in JSON format. For instance if I've a key foobar with a json object I can alter the "name" file using somthing like: "JSON SET foobar name Kevin". We should have GET and INCRBY as well.
	43
3f477979	44	OTHER IMPORTANT THINGS THAT WILL BE ADDED BUT I'M NOT SURE WHEN
	45	===============================================================
	46
	47	BIG ONES:
	48
	49	* Specially encoded memory-saving integer sets.
	50	* A command to export a JSON dump (there should be mostly working patch needing major reworking).
	51
	52	SMALL ONES:
	53
	54	* Give errors when incrementing a key that does not look like an integer, when providing as a sorted set score something can't be parsed as a double, and so forth.
25e52257	55	* MSADD (n keys) (n values). See this thread in the Redis google group: http://groups.google.com/group/redis-db/browse_thread/thread/e766d84eb375cd41
3f477979	56
c35f7d5b	57	SHORT/LONG TERM RANDOM TODO ITEMS
c35f7d5b	58	=================================
f6b141c5	59
0188805d	60	Most of this can be seen just as proposals, the fact they are in this list
	61	it's not a guarantee they'll ever get implemented ;)
	62
57033301	63	* Move dict.c from hash table to skip list, in order to avoid the blocking resize operation needed for the hash table.
682ac724	64	* FORK command (fork()s executing the commands received by the current
	65	client in the new process). Hint: large SORTs can use more cores,
	66	copy-on-write will avoid memory problems.
	67	* DUP command? DUP srckey dstkey, creates an exact clone of srckey value in dstkey.
	68	* SORT: Don't copy the list into a vector when BY argument is constant.
	69	* Write the hash table size of every db in the dump, so that Redis can resize the hash table just one time when loading a big DB.
	70	* LOCK / TRYLOCK / UNLOCK as described many times in the google group
	71	* Replication automated tests
	72	* Byte Array type (BA prefixed commands): BASETBIT BAGETBIT BASETU8 U16 U32 U64 S8 S16 S32 S64, ability to atomically INCRBY all the base types. BARANGE to get a range of bytes as a bulk value, BASETRANGE to set a range of bytes.
	73	* zmalloc() should avoid to add a private header for archs where there is some other kind of libc-specific way to get the size of a malloced block. Already done for Mac OS X.
	74	* Read-only mode.
	75	* Pattern-matching replication.
3f477979	76	* Don't save empty lists / sets / zsets on disk with snapshotting.
b32627cd	77	* Remove keys when a list / set / zset reaches length of 0.
ac945e2d	78	* Add an option to relax the delete-expiring-keys-on-write semantic denying replication and AOF when this is on? Can be handy sometimes, when using Redis for non persistent state, but can create problems. For instance should rename and move also "move" the timeouts? How does this affect other commands?
682ac724	79
	80	DOCUMENTATION WISHLIST
	81	======================
	82
	83	* Page explaining tips to reduce memory usage.
	84	* A Sorted sets HOWTO
	85