Fixed a never experienced, theoretical bug that can actually happen in practice....

[redis.git] / TODO

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-VERSION 1.1 TODO
+Redis TODO and Roadmap

 
 

-* For now only the last argument gets integer encoded, so make sure that: 1) every multi bulk commands implemented will have the last arg that is indeed a value, and not used otherwise. 2) to explicitly call the function to encode the object in MSET and other commands where there are multiple "values".
-* Man pages for MSET MSETNX and SRANDMEMBER, Z-commands, ...
-* ZSETs missing stuff: ZINCRBY
-* Use strcoll() to compare objects in sorted sets, like it already happens for SORT.
-* LPOPPUSH, EXPIRE, EXPIREAT, ZSCORE, SRANDMEMBER tests.
-* Write docs for the "STORE" operaiton of SORT, and GET "#" option.
-* Append only mode: testing and a command to rebuild the log from scratch.
-* Redis-cli should be able to select a different DB than 0 using some switch.
+VERSION 1.4 TODO (Hash type)
+============================

 
 

-VERSION 1.2 TODO
+* BRPOPLPUSH
+* RPOPLPUSH should notify blocking POP operations
+* List ops like L/RPUSH L/RPOP should return the new list length.
+* Save dataset / fsync() on SIGTERM
+* MULTI/EXEC should support the "EXEC FSYNC" form
+* Synchronous Virtual Memory
+* BLPOP & C. tests (write a non blocking Tcl client as first step)

 
 

-* Basic Redis-cluster (at least all the features of the Ruby client distribute implementation + ability to set every key in M nodes).
+Virtual Memory sub-TODO:
+* Check if the page selection algorithm is working well.
+* Divide swappability of objects by refcount
+* vm-swap-file <filename>. The swap file should go where the user wants, and if it's already there and of the right size we can avoid to create it again.
+* it should be possible to give the vm-max-memory option in megabyte, gigabyte, ..., just using 2GB, 100MB, and so forth.
+* Make sure to wait all the IO threads are done before to fork() for BGSAVE and BGREWRITEAOF
+* Enlarge the stack of threads, to problems when calling LZF lib.
+* redis-cli vmstat, calling INFO every second and printing VM stats ala vmstat.
+
+VERSION 1.6 TODO (Virtual memory)
+=================================
+
+* Asynchronous Virtual Memory

 * Hashes (HSET, HGET, HEXISTS, HLEN, ...).
 * Hashes (HSET, HGET, HEXISTS, HLEN, ...).

-* An utility able to export an .rdb file into a text-only JSON dump, we can't live anymore without such a tool. Probably an extension to redis-cli.

 
 

-LONG TERM TODO
+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).
+* Specially encoded sets of integers (this includes a big refactoring providing an higher level layer for Sets manipulation)
+* ZRANK: http://docs.google.com/viewer?a=v&q=cache:tCQaP3ZeN4YJ:courses.csail.mit.edu/6.046/spring04/handouts/ps5-sol.pdf+skip+list+rank+operation+augmented&hl=en&pid=bl&srcid=ADGEEShXuNjTcZyXw_1cq9OaWpSXy3PprjXqVzmM-LE0ETFznLyrDXJKQ_mBPNT10R8ErkoiXD9JbMw_FaoHmOA4yoGVrA7tZWiy393JwfCwuewuP93sjbkzZ_gnEp83jYhPYjThaIzw&sig=AHIEtbRF0GkYCdYRFtTJBE69senXZwFY0w
+
+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
+* Don't save empty lists / sets / zsets on disk with snapshotting.
+* Remove keys when a list / set / zset reaches length of 0.

 
 

- * Add a command to inspect the currently selected DB index
- * Consistent hashing implemented in all the client libraries having an user base
- * SORT: Don't copy the list into a vector when BY argument is constant.
- * Profiling and optimization in order to limit the CPU usage at minimum
- * 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.
- * Elapsed time in logs for SAVE when saving is going to take more than 2 seconds
- * LOCK / TRYLOCK / UNLOCK as described many times in the google group
- * Replication automated tests
- * BITMAP / BYTEARRAY type?
- * 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.
+THE "MAYBE" TODO LIST: things that may or may not get implemented
+=================================================================

 
 

-FUTURE HINTS
+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 ;)

 
 

-- In memory compression: if in-memory values compression will be implemented, make sure to implement this so that addReply() is able to handle compressed objects, just creating an uncompressed version on the fly and adding this to the output queue instead of the original one. When insetad we need to look at the object string value (SORT BY for example), call a function that will turn the object into an uncompresed one. (Note, Redis 1.1 beta already has this feature actually, but is for now only used to compress strings representing integers)
+* 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.
+* 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?
+* Multiple BY in SORT.