Redis的事务设置的命令与执行设置（代码）

SQL是Structured Query Language(结构化查询语言)的缩写。SQL是专为数据库而建立的操作命令集，是一种功能齐全的数据库语言。在使用它时，只需要发出“做什么”的命令，“怎么做”是不用使用者考虑的。SQL功能强大、简单易学、使用方便，已经成为了数据库操作的基础，并且现在几乎所有的数据库均支持SQL。

本篇文章给大家带来的内容是关于Redis的事务操作的命令与执行操作（代码），有一定的参考价值，有需要的朋友可以参考一下，希望对你有所帮助。

序

本文主要研究一下redis的事务操作

命令

multi与exec

命令行

127.0.0.1:6379> multi
OK
127.0.0.1:6379> incr total
QUEUED
127.0.0.1:6379> incr len
QUEUED
127.0.0.1:6379> exec
1) (integer) 2
2) (integer) 2
127.0.0.1:6379> get total
"2"
127.0.0.1:6379> get len
"2"

lettuce实例

    @Test
    public void testMultiExec(){
        RedisClient client = RedisClient.create("redis://192.168.99.100:6379/0");
        StatefulRedisConnection<String, String> connection = client.connect();
        RedisCommands<String, String> syncCommands = connection.sync();

        syncCommands.set("hello","1");
        syncCommands.set("world","2");

        syncCommands.multi();
        syncCommands.incr("hello");
        syncCommands.incr("world");

        //DefaultTransactionResult[wasRolledBack=false,result=[1, 2, 1, 3, 1]]
        TransactionResult transactionResult = syncCommands.exec();
        System.out.println(transactionResult);
        System.out.println(syncCommands.get("hello"));
        System.out.println(syncCommands.get("world"));
    }

部分执行

命令行

127.0.0.1:6379> multi
OK
127.0.0.1:6379> set a hello
QUEUED
127.0.0.1:6379> set b world
QUEUED
127.0.0.1:6379> incr a
QUEUED
127.0.0.1:6379> set c part
QUEUED
127.0.0.1:6379> exec
1) OK
2) OK
3) (error) ERR value is not an integer or out of range
4) OK
127.0.0.1:6379> get a
"hello"
127.0.0.1:6379> get b
"world"
127.0.0.1:6379> get c
"part"

lettuce实例

    @Test
    public void testMultiExecError(){
        RedisClient client = RedisClient.create("redis://192.168.99.100:6379/0");
        StatefulRedisConnection<String, String> connection = client.connect();
        RedisCommands<String, String> syncCommands = connection.sync();

        syncCommands.multi();
        syncCommands.set("a","hello");
        syncCommands.set("b","world");
        syncCommands.incr("a");
        syncCommands.set("c","part");
        //DefaultTransactionResult[wasRolledBack=false,result=[OK, OK, io.lettuce.core.RedisCommandExecutionException: ERR value is not an integer or out of range, OK, 1]]
        TransactionResult transactionResult = syncCommands.exec();
        System.out.println(transactionResult);
        System.out.println(syncCommands.get("a"));
        System.out.println(syncCommands.get("b"));
        System.out.println(syncCommands.get("c"));
    }

multi与discard

命令行

127.0.0.1:6379> set sum 1
OK
127.0.0.1:6379> multi
OK
127.0.0.1:6379> incr sum
QUEUED
127.0.0.1:6379> discard
OK
127.0.0.1:6379> get sum
"1"

lettuce实例

    @Test
    public void testMultiDiscard(){
        RedisClient client = RedisClient.create("redis://192.168.99.100:6379/0");
        StatefulRedisConnection<String, String> connection = client.connect();
        RedisCommands<String, String> syncCommands = connection.sync();
        syncCommands.incr("key1");
        syncCommands.multi();
        syncCommands.incr("key1");
        //需要有multi才可以执行discard，成功返回OK
        String result = syncCommands.discard();
        System.out.println(result);
        System.out.println(syncCommands.get("key1"));
    }

check and set

    @Test
    public void testWatch(){
        RedisClient client = RedisClient.create("redis://192.168.99.100:6379/0");
        StatefulRedisConnection<String, String> connection = client.connect();
        RedisCommands<String, String> syncCommands = connection.sync();

        String key = "key";
        syncCommands.watch(key);

        //another connection
        StatefulRedisConnection<String, String> conn2 = client.connect();
        RedisCommands<String, String> syncCommands2 = conn2.sync();
        syncCommands2.set(key, "a");

        syncCommands.multi();
        syncCommands.append(key, "b");
        //DefaultTransactionResult [wasRolledBack=true, responses=0]
        TransactionResult transactionResult = syncCommands.exec();
        System.out.println(transactionResult);

        System.out.println(syncCommands.get(key));
    }

小结

reids提供multi exec/discard指令，类似open commit/rollback transaction，不过exec遇到类型操作等错误时不会滚，该成功执行的命令还是成功执行，该失败的还是失败
multi exec保证的是，只要exec命令有执行成功，则事务中一系列的命令都能执行，如果exec因为网络等问题，server端没有接收到，则事务中的一系列命令都不会被执行
discard需要在有调用multi的前提下才能使用，该命令会清空事务队列等待执行的命令
redis提供watch指令，可以配合multi exec来使用，可以实现类似数据库的乐观锁的机制，一旦watch的key被其他client有更新，则整个exec操作失败

以上就是Redis的事务操作的命令与执行操作（代码）的详细内容，更多请关注php中文网其它相关文章！

学习教程快速掌握从入门到精通的SQL知识。

……

标签:Redis的事务设置的命令与执行设置（代码）