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Lua scripts are executed in the context of the currently selected database (as selected by the caller of the script). However Lua scripts are also free to use the SELECT command in order to affect other DBs. When SELECT is called frm Lua, the old behavior, before this commit, was to automatically set the Lua caller selected DB to the last DB selected by Lua. See for example the following sequence of commands: SELECT 0 SET x 10 EVAL "redis.call('select','1')" 0 SET x 20 Before this commit after the execution of this sequence of commands, we'll have x=10 in DB 0, and x=20 in DB 1. Because of the problem above, there was a bug affecting replication of Lua scripts, because of the actual implementation of replication. It was possible to fix the implementation of Lua scripts in order to fix the issue, but looking closely, the bug is the consequence of the behavior of Lua ability to set the caller's DB. Under the old semantics, a script selecting a different DB, has no simple ways to restore the state and select back the previously selected DB. Moreover the script auhtor must remember that the restore is needed, otherwise the new commands executed by the caller, will be executed in the context of a different DB. So this commit fixes both the replication issue, and this hard-to-use semantics, by removing the ability of Lua, after the script execution, to force the caller to switch to the DB selected by the Lua script. The new behavior of the previous sequence of commadns is to just set X=20 in DB 0. However Lua scripts are still capable of writing / reading from different DBs if needed. WARNING: This is a semantical change that will break programs that are conceived to select the client selected DB via Lua scripts. This fixes issue #1811.
Where to find complete Redis documentation? ------------------------------------------- This README is just a fast "quick start" document. You can find more detailed documentation at http://redis.io Building Redis -------------- Redis can be compiled and used on Linux, OSX, OpenBSD, NetBSD, FreeBSD. We support big endian and little endian architectures. It may compile on Solaris derived systems (for instance SmartOS) but our support for this platform is "best effort" and Redis is not guaranteed to work as well as in Linux, OSX, and *BSD there. It is as simple as: % make You can run a 32 bit Redis binary using: % make 32bit After building Redis is a good idea to test it, using: % make test Fixing problems building 32 bit binaries --------- If after building Redis with a 32 bit target you need to rebuild it with a 64 bit target, or the other way around, you need to perform a "make distclean" in the root directory of the Redis distribution. In case of build errors when trying to build a 32 bit binary of Redis, try the following steps: * Install the packages libc6-dev-i386 (also try g++-multilib). * Try using the following command line instead of "make 32bit": make CFLAGS="-m32 -march=native" LDFLAGS="-m32" Allocator --------- Selecting a non-default memory allocator when building Redis is done by setting the `MALLOC` environment variable. Redis is compiled and linked against libc malloc by default, with the exception of jemalloc being the default on Linux systems. This default was picked because jemalloc has proven to have fewer fragmentation problems than libc malloc. To force compiling against libc malloc, use: % make MALLOC=libc To compile against jemalloc on Mac OS X systems, use: % make MALLOC=jemalloc Verbose build ------------- Redis will build with a user friendly colorized output by default. If you want to see a more verbose output use the following: % make V=1 Running Redis ------------- To run Redis with the default configuration just type: % cd src % ./redis-server If you want to provide your redis.conf, you have to run it using an additional parameter (the path of the configuration file): % cd src % ./redis-server /path/to/redis.conf It is possible to alter the Redis configuration passing parameters directly as options using the command line. Examples: % ./redis-server --port 9999 --slaveof 127.0.0.1 6379 % ./redis-server /etc/redis/6379.conf --loglevel debug All the options in redis.conf are also supported as options using the command line, with exactly the same name. Playing with Redis ------------------ You can use redis-cli to play with Redis. Start a redis-server instance, then in another terminal try the following: % cd src % ./redis-cli redis> ping PONG redis> set foo bar OK redis> get foo "bar" redis> incr mycounter (integer) 1 redis> incr mycounter (integer) 2 redis> You can find the list of all the available commands here: http://redis.io/commands Installing Redis ----------------- In order to install Redis binaries into /usr/local/bin just use: % make install You can use "make PREFIX=/some/other/directory install" if you wish to use a different destination. Make install will just install binaries in your system, but will not configure init scripts and configuration files in the appropriate place. This is not needed if you want just to play a bit with Redis, but if you are installing it the proper way for a production system, we have a script doing this for Ubuntu and Debian systems: % cd utils % ./install_server.sh The script will ask you a few questions and will setup everything you need to run Redis properly as a background daemon that will start again on system reboots. You'll be able to stop and start Redis using the script named /etc/init.d/redis_<portnumber>, for instance /etc/init.d/redis_6379. Code contributions --- Note: by contributing code to the Redis project in any form, including sending a pull request via Github, a code fragment or patch via private email or public discussion groups, you agree to release your code under the terms of the BSD license that you can find in the COPYING file included in the Redis source distribution. Please see the CONTRIBUTING file in this source distribution for more information. Enjoy!
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