X-Git-Url: https://git.saurik.com/redis.git/blobdiff_plain/28173a49a7f6c8d5850f70c26874f3cba6f64941..e74825c24f134cf75e2285ecaf8d379bc8e7d28e:/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, ...
-* Use strcoll() to compare objects in sorted sets, like it already happens for SORT.
-* Tests for: ZINCRBY, SRANDMEMBER, SORT with #.
-* Write docs for the "STORE" operaiton of SORT, and GET "#" option.
-* Append only mode: testing and a command to rebuild the log from scratch.
+VERSION 2.0 TODO
+================
 
-VERSION 1.2 TODO
+* BRPOPLPUSH
+* 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?
+* BLPOP & C. tests (write a non blocking Tcl client as first step)
+* ZCOUNT sortedset min max
+* 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
+* Once ZRANK is implemented, change the implementation of ZCOUNT to use the augmented skiplist in order to be much faster.
+* Write doc for ZCOUNT, and for open / closed intervals of sorted sets range operations.
 
-* Basic Redis-cluster (at least all the features of the Ruby client distribute implementation + ability to set every key in M nodes).
-* 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.
+Virtual Memory sub-TODO:
+* Check if the page selection algorithm is working well
+* Divide swappability of objects by refcount
+* Use multiple open FDs against the VM file, one for thread.
+* it should be possible to give the vm-max-memory option in megabyte, gigabyte, ..., just using 2GB, 100MB, and so forth.
+* Try to understand what can be moved into I/O threads that currently is instead handled by the main thread. For instance swapping file table scannig to find contiguous page could be a potential candidate (but I'm not convinced it's a good idea, better to improve the algorithm, for instance double the fast forward at every step?).
+* Possibly decrRefCount() against swapped objects can be moved into I/O threads, as it's a slow operation against million elements list, and in general consumes CPU time that can be consumed by other threads (and cores).
+* EXISTS should avoid loading the object if possible without too make the code too specialized.
+* vm-min-age <seconds> option
+* Make sure objects loaded from the VM are specially encoded when possible.
+* Check what happens performance-wise if instead to create threads again and again the same threads are reused forever. Note: this requires a way to disable this clients in the child, but waiting for empty new jobs queue can be enough.
+* Sets of integers are slow to load, for a number of reasons. Fix it. (use slow_sets.rdb file for debugging). (p.s. this was now partially fixed).
+* On EXEC try to block the client until relevant keys are loaded.
 
-LONG TERM TODO
+* Hashes (GET/SET/DEL/INCRBY/EXISTS/FIELDS/LEN/MSET/MGET). Special encoding for hashes with less than N elements.
+* Write documentation for APPEND
+* Implement LEN, SUBSTR, PEEK, POKE, SETBIT, GETBIT
 
- * 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.
+VERSION 2.2 TODO (Fault tolerant sharding)
+===========================================
 
-FUTURE HINTS
+* Redis-cluster, a fast intermediate layer (proxy) that implements consistent hashing and fault tollerant nodes handling.
 
-- 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)
+Interesting readings about this:
+
+    - http://ayende.com/Blog/archive/2009/04/06/designing-rhino-dht-a-fault-tolerant-dynamically-distributed-hash.aspx
+
+VERSION 2.4 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.
+
+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)
+
+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.
+* An option to exec a command slave-side if the master connection is lost: even cooler: if the script returns "0" the slave elects itself as master, otherwise continue trying to reconnect.
+
+THE "MAYBE" TODO LIST: things that may or may not get implemented
+=================================================================
+
+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.
+* 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.