Redis持久化:How Redis writes data to disk(怎么把数据从内存中写入硬盘) 一、RDB(Redis Database) RDB:以指定的时间间隔执行数据集的时间点快照(snapshot),将数据和状态以文件的形式写入磁盘,快照文件称为RDB文件(dump.rdb),保存备份是它执行的是全量快照(保存内存中的全部数
下面是RDB持久化的流程图: Redis ServerSave data to RDB fileStartFork child processChild process writes data to diskChild process exits RDB持久化的过程可以通过以下代码示例来实现: importredis# 连接到Redis服务器r=redis.Redis(host='localhost',port=6379,db=0)# 保存数据到RDB文件r.save() 1. 2. ...
(二)Append-only file aof 比快照方式有更好的持久化性,是由于在使用aof持久化方式时,redis会将每一个收到的写命令都通过write函数追加到文件中(默认是appendonly.aof)。当redis重启时会通过重新执行文件中保存的写命令来在内存中重建整个数据库的内容。当然由于os会在内核中缓存 write做的修改,所以可能不是立即...
如果满足则通过操作系统fork调用来创建出一个子进程,这个子进程默认会与父进程共享相同的地址空间,这时就可以通过子进程来遍历整个内存来进行存储操作,而主进程则仍然可以提供服务,当有写入时由操作系统按照内存页(page)为单位来进行copy-on-write保证父子进程之间不会互相影响。
RDB 指对整个数据集在特定时间点生成快照 (point-to-time snapshot), 可用于Redis的数据备份, 转移和恢复. 它是 Redis 默认使用的持久化方案. 工作原理 RDB 利用操作系统提供的写时复制(Copy-on-Write) 机制来进行持久化, 即当主进程 P fork 出子进程时 Q 时, Q 和 P 共享同一块内存空间, 当 P 准备...
告诉父进程,停止发送aof增量数据给子进程 */ if (write(server.aof_pipe_write_ack_to_parent,"!",1) != 1) goto werr; if (anetNonBlock(NULL,server.aof_pipe_read_ack_from_parent) != ANET_OK) goto werr; /* 上面发送了"!",等待父进程回"!" */ if (syncRead(server.aof_pipe_read_ack...
(NULL, 2621440, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x7fe7db452000 write(1, "19831:M 20 May 2020 06:53:08.516 * Starting BGSAVE for SYNC with target: disk\n", 78) = 78 pipe([8, 9]) = 0 fcntl(8, F_GETFL) = 0 (flags O_RDONLY) ...
3 total_writes_processed:2 io_threaded_reads_processed:0 io_threaded_writes_processed:0 # Sentinel sentinel_masters:1 sentinel_tilt:0 sentinel_running_scripts:0 sentinel_scripts_queue_length:0 sentinel_simulate_failure_flags:0 master0:name=tmlmaster,status=ok,address=127.0.0.1:6379,slaves=2,...
MISCONF Redis is configured to save RDB snapshots, but it is currently not able to persist on disk. Commands that may modify the data set are disabled, because this instance is configured to report errors during writes if RDB snapshotting fails (stop-writes-on-bgsave-error option). Please...
Caching: quickly access frequently used data without needing to query your primary database Session management: read and write user session data without hurting user experience or slowing down every API call Querying, sorting, and analytics: perform deduplication, full text search, and secondary indexi...