00-RELEASENOTES

   1 Redis 2.6 release notes
   2 =======================
   3
   4 ** IMPORTANT ** Check the 'Migrating from 2.4 to 2.6' section at the end of
   5                 this file for information about what changed between 2.4 and
   6                 2.6 and how this may affect your application.
   7
   8 --------------------------------------------------------------------------------
   9 Upgrade urgency levels:
  10
  11 LOW:      No need to upgrade unless there are new features you want to use.
  12 MODERATE: Program an upgrade of the server, but it's not urgent.
  13 HIGH:     There is a critical bug that may affect a subset of users. Upgrade!
  14 CRITICAL: There is a critical bug affecting MOST USERS. Upgrade ASAP.
  15 --------------------------------------------------------------------------------
  16
  17 ---[ Redis 2.6.1 ]
  18
  19 * [BUGFIX]   Compilation on Linux < 2.6.17 or glibc < 2.6 fixed (RHLE5 & co).
  20
  21 ---[ Redis 2.6.0 ]
  22
  23 * [BUGFIX]   Allow AUTH when server is in -BUSY state because of a slow script.
  24 * [BUGFIX]   MULTI/EXEC flow now makes sense when observed in MONITOR
  25 * [BUGFIX]   SCRIPT KILL now uses different error prefixes for different errors.
  26 * [BUGFIX]   Default memory limit for 32bit archs lowered from 3.5 to 3 GB.
  27 * [BUGFIX]   redis-check-dump is now compatible with RDB files generated by 2.6.
  28 * [IMPROVED] New field in INFO: slave_read_only.
  29
  30 ---[ Redis 2.5.14 (2.6 Release Candidate 8) ]
  31
  32 * [BUGFIX]   Fixed compilation on FreeBSD.
  33 * [IMPROVED] SRANDMEMBER <count> that returns multiple random elements.
  34 * [IMPROVED] Sentinel backported to 2.6. It will be taken in sync with 2.8.
  35 * [IMPROVED] Helper function for scripting to return errors and status replies.
  36 * [IMPROVED] SORT by nosort [ASC|DESC] uses sorted set elements ordering.
  37 * [BUGFIX]   Better resistence to system clock skew.
  38 * [IMPROVED] Warn the user when the configured maxmemory seems odd.
  39 * [BUGFIX]   Hashing function is now murmurhash2 for security purposes.
  40 * [IMPROVED] Install script no longer uses a template but redis.conf itself.
  41
  42 ---[ Redis 2.5.13 (2.6 Release Candidate 7) ]
  43
  44 UPGRADE URGENCY: HIGH
  45
  46 * [BUGFIX]   Theoretical bug in ziplist fixed.
  47 * [BUGFIX]   Better out of memory handling (Log produced in log file).
  48 * [BUGFIX]   Incrementally flush RDB file on slave side while performing the
  49              first synchronization with the master. This makes Redis less
  50              blocking in environments where disk I/O is slow.
  51 * [BUGFIX]   Don't crash with Lua's redis.call() without arguments.
  52 * [BUGFIX]   Don't crash after a big number of Lua calls on 32 bit systems
  53              because of a failed assertion.
  54 * [BUGFIX]   Fix SORT behaviour when called from scripting.
  55 * [BUGFIX]   Adjust slave PING period accordingly to REDIS_HZ define.
  56 * [BUGFIX]   BITCOUNT: fix crash on overflowing arguments.
  57 * [BUGFIX]   Return an error when SELECT argument is not an integer.
  58 * [BUGFIX]   Blocking operations on lists were completely reimplemented for
  59              correctness. Now blocking list ops and pushes originated from
  60              Lua scripts will play well together and will be replicated
  61              and transmitted to the AOF correctly.
  62 * [IMPROVED] Send async PING before starting replication to avoid blocking if
  63              master allows us to connect but it is actually not able to reply.
  64 * [IMPROVED] Support slave-priority for Redis Sentinel.
  65 * [IMPROVED] Hiredis library updated.
  66
  67 ---[ Redis 2.5.12 (2.6 Release Candidate 6) ]
  68
  69 UPGRADE URGENCY: MODERATE.
  70
  71 * [BUGFIX]   Fixed a timing attack on AUTH (Issue #560).
  72 * [BUGFIX]   Don't assume that "char" is signed.
  73 * [BUGFIX]   Check that we have connection before enabling pipe mode.
  74 * [BUGFIX]   Use the optimized version of the function to convert a double to
  75              its string representation. Compilation was disabled because of
  76              a typo in the #if statement.
  77 * [IMPROVED} REPLCONF internal command introduced, now INFO shows slaves with
  78              correct port numbers. This makes 2.5.12 Redis Sentinel compatible.
  79 * [IMPROVED] Truncate short write from the AOF for a cleaner restart. On short
  80              writes (for instance out of space) Redis will now try to remove
  81              the half-written data so that the next restart will work without
  82              the need for the "redis-check-aof" utility.
  83 * [IMPROVED] New in INFO: aof_last_bgrewrite_status
  84 * [IMPROVED] Allow Pub/Sub in contexts where other commands are blocked.
  85 * [BUGFIX]   mark fd as writable when EPOLLERR or EPOLLHUP is returned by
  86              epoll_wait.
  87
  88 ---[ Redis 2.5.11 (2.6 Release Candidate 5) ]
  89
  90 UPGRADE URGENCY: HIGH.
  91
  92 * [BUGFIX]   Fixed Hash corruption when loading an RDB file generated by
  93              previous versions of Redis that encoded hashes using
  94              a different ziplist encoding format for small integers.
  95              All the fileds that are integers in the range 0-255 may not
  96              be recognized, or duplicated un updates, causing a crash
  97              when the ziplist is converted to a real hash. (Issue #547).
  98 * [BUGFIX]   Fixed the count of memory used by output buffers in the
  99              setDeferredMultiBulkLength() function.
 100
 101 ---[ Redis 2.5.10 (2.6 Release Candidate 4) ]
 102
 103 UPGRADE URGENCY: HIGH.
 104
 105 * [BUGFIX]   Allow PREFIX to be overwritten on "make install".
 106 * [BUGFIX]   Run the test with just one client if the computer is slow.
 107 * [BUGFIX]   Event port support in our event driven libray.
 108 * [BUGFIX]   Jemalloc updated to 3.0.0. This fixes a possibly AOF rewrite issue.
 109              See https://github.com/antirez/redis/issues/504 for info.
 110 * [BUGFIX]   Fixed issue #516: ZINTERSTORE / ZUNIONSTORE with mixed sets/zsets.
 111 * [BUGFIX]   Set fd to writable when poll(2) detects POLLERR or POLLHUP event.
 112 * [BUGFIX]   Fixed RESTORE hash failure (Issue #532).
 113 * [IMPROVED] Allow an AOF rewrite buffer > 2GB (Related to issue #504).
 114 * [IMPROVED] Server cron function frequency is now configurable (REDIS_HZ).
 115 * [IMPROVED] Better, less blocking expired keys collection algorithm.
 116 * [FEATURE]  New commands: BITOP and BITCOUNT.
 117 * [FEATURE]  redis-cli --pipe for mass import.
 118
 119 What's new in Redis 2.5.9 (aka 2.6 Release Candidate 3)
 120 =======================================================
 121
 122 UPGRADE URGENCY: critical, upgrade ASAP.
 123
 124 * [BUGFIX] Fix for issue #500 (https://github.com/antirez/redis/pull/500).
 125            Redis 2.6-RC1 and RC2 may corrupt ziplist-encoded sorted sets
 126            produced by Redis 2.4.x.
 127 * [BUGFIX] Fixed several bugs in init.d script.
 128 * [BUGFIX] syncio.c functions modified for speed and correctness. On osx
 129            (and possibly other BSD-based systems) the slave would block on
 130            replication to send the SYNC command when the master was not
 131            available. This is fixed now, but was not affecting Linux installs.
 132 * Now when slave-serve-stale-data is set to yes and the master is down, instead
 133   of reporting a generic error Redis replies with -MASTERDOWN.
 134
 135 What's new in Redis 2.5.8 (aka 2.6 Release Candidate 2)
 136 =======================================================
 137
 138 UPGRADE URGENCY: high for all the users of the KEYS command, otherwise low.
 139
 140 * [BUGFIX] Fix for KEYS command: if the DB contains keys with expires the KEYS
 141            command may return the wrong output, having duplicated or missing
 142            keys. See issue #487 and #488 on github for details.
 143
 144 What's new in Redis 2.5.7 (aka 2.6 Release Candidate 1)
 145 =======================================================
 146
 147 UPGRADE URGENCY: upgrade not recommended because this is an RC release.
 148
 149 * This is the first release candidate for Redis 2.6. We are not aware of
 150   bugs, but part of this code is young and was never tested in production
 151   environments, so handle with care.
 152
 153 An overview of new features and changes in Redis 2.6.x
 154 ======================================================
 155
 156 * Server side Lua scripting, see http://redis.io/commands/eval
 157 * Virtual Memory removed (was deprecated in 2.4)
 158 * Hardcoded limits about max number of clients removed.
 159 * AOF low level semantics is generally more sane, and especially when used
 160   in slaves.
 161 * Milliseconds resolution expires, also added new commands with milliseconds
 162   precision (PEXPIRE, PTTL, ...).
 163 * Better memory usage for "small" lists, ziplists and hashes when fields or
 164   values contain small integers.
 165 * Read only slaves.
 166 * New bit opeations: BITCOUNT and BITOP commands.
 167 * Clients max output buffer soft and hard limits. You can specifiy different
 168   limits for different classes of clients (normal,pubsub,slave).
 169 * More incremental (less blocking) expired keys collection algorithm, in
 170   practical terms this means that Redis is more responsive when a very
 171   big number of keys expire about at the same time.
 172 * AOF is now able to rewrite aggregate data types using variadic commands,
 173   often producing an AOF that is faster to save, load, and is smaller in size.
 174 * Every redis.conf directive is now accepted as a command line option for the
 175   redis-server binary, with the same name and number of arguments.
 176 * Hash table seed randomization for protection against collisions attacks.
 177 * Performances improved when writing large objects to Redis.
 178 * Integrated memory test, see redis-server --test-memory.
 179 * INCRBYFLOAT and HINCRBYFLOAT commands.
 180 * New DUMP, RESTORE, MIGRATE commands (back ported from Redis Cluster to 2.6).
 181 * CRC64 checksump in RDB files.
 182 * Better MONITOR output and behavior (now commands are logged before execution).
 183 * "Software Watchdog" feature to debug latency issues.
 184 * Significant parts of the core refactored or rewritten. New internal APIs
 185   and core changes allowed to develop Redis Cluster on top of the new code,
 186   however for 2.6 all the cluster code was removed, and will be released with
 187   Redis 3.0 when it is more complete and stable.
 188 * Redis ASCII art logo added at startup.
 189 * Crash report on memory violation or failed asserts improved significantly
 190   to make debugging of hard to catch bugs simpler.
 191 * redis-benchmark improvements: ability to run selected tests,
 192   CSV output, faster, better help.
 193 * redis-cli improvements: --eval for comfortable development of Lua scripts.
 194 * SHUTDOWN now supports two optional arguments: "SAVE" and "NOSAVE".
 195 * INFO output split into sections, the command is now able to just show
 196   pecific sections.
 197 * New statistics about how many time a command was called, and how much
 198   execution time it used (INFO commandstats).
 199 * More predictable SORT behavior in edge cases.
 200 * Better support for big endian and *BSD systems.
 201 * Build system improved.
 202
 203 Migrating from 2.4 to 2.6
 204 =========================
 205
 206 Redis 2.4 is mostly a strict subset of 2.6. However there are a few things
 207 that you should be aware of:
 208
 209 * You can't use .rdb and AOF files generated with 2.6 into a 2.4 instance.
 210 * 2.6 slaves can be attached to 2.4 masters, but not the contrary, and only
 211   for the time needed to perform the version upgrade.
 212
 213 There are also a few API differences, that are unlikely to cause problems,
 214 but it is better to keep them in mind:
 215
 216 * SORT now will refuse to sort in numerical mode elements that can't be parsed
 217   as numbers.
 218 * EXPIREs now all have millisecond resolution (but this is very unlikely to
 219   break code that was not conceived exploting the previous resolution error
 220   in some way.)
 221 * INFO output is a bit different now, and contains empty lines and comments
 222   starting with '#'. All the major clients should be already fixed to work
 223   with the new INFO format.
 224 * Slaves are only read-only by default (but you can change this easily
 225   setting the "slave-read-only" configuration option to "no" editing your
 226   redis.conf or using CONFIG SET.
 227
 228 The following INFO fields were renamed for consistency:
 229
 230      changes_since_last_save -> rdb_changes_since_last_save
 231      bgsave_in_progress -> rdb_bgsave_in_progress
 232      last_save_time -> rdb_last_save_time
 233      last_bgsave_status -> rdb_last_bgsave_status
 234      bgrewriteaof_in_progress -> aof_rewrite_in_progress
 235      bgrewriteaof_scheduled -> aof_rewrite_scheduled
 236
 237 The following redis.conf and CONFIG GET / SET parameters changed:
 238
 239     * hash-max-zipmap-entries, now replaced by hash-max-ziplist-entries
 240     * hash-max-zipmap-value, now replaced by hash-max-ziplist-value
 241     * glueoutputbuf option was now completely removed (was deprecated)
 242
 243 --------------------------------------------------------------------------------
 244
 245 Credits: Where not specified the implementation and design are done by
 246 Salvatore Sanfilippo and Pieter Noordhuis. Thanks to VMware for making all
 247 this possible. Also many thanks to all the other contributors and the amazing
 248 community we have.
 249
 250 See commit messages for more credits.
 251
 252 Cheers,
 253 Salvatore