Redis 简介
Redis 是完全开源的，遵守 BSD 协议，是一个高性能的 key-value 数据库。
Redis 与其他 key - value 缓存产品有以下三个特点：
- Redis支持数据的持久化，可以将内存中的数据保存在磁盘中，重启的时候可以再次加载进行使用。
- Redis不仅仅支持简单的key-value类型的数据，同时还提供list，set，zset，hash等数据结构的存储。
- Redis支持数据的备份，即master-slave模式的数据备份。
Redis 优势
- 性能极高 – Redis能读的速度是110000次/s,写的速度是81000次/s 。
- 丰富的数据类型 – Redis支持二进制案例的 Strings, Lists, Hashes, Sets 及 Ordered Sets 数据类型操作。
- 原子 – Redis的所有操作都是原子性的，意思就是要么成功执行要么失败完全不执行。单个操作是原子性的。多个操作也支持事务，即原子性，通过MULTI和EXEC指令包起来。
- 丰富的特性 – Redis还支持 publish/subscribe, 通知, key 过期等等特性。
# 我的理解相当于MySQL或oracle中的插入一条数据 set key value
127.0.0.1:6379> set key1 value1
OK
# 根据key获取value值
127.0.0.1:6379> get key1
"value1"
127.0.0.1:6379>
redis的info命令，监控redis性能指标，一般我关注的是内存占用，只关注内存也可以用info menory命令
127.0.0.1:6379> info # Server redis_version:5.0.5 redis_git_sha1:00000000 redis_git_dirty:0 redis_build_id:5366cb12da65632 redis_mode:standalone os:Linux 2.6.32-431.el6.x86_64 x86_64 arch_bits:64 multiplexing_api:epoll atomicvar_api:sync-builtin gcc_version:4.4.7 process_id:6757 run_id:673a5c474f28755a15f34983a28e403fc20726c1 tcp_port:6379 uptime_in_seconds:24404 uptime_in_days:0 hz:10 configured_hz:10 lru_clock:2195344 executable:/usr/local/redis-5.0.5/redis-server config_file:/usr/local/redis-5.0.5/redis.conf # Clients connected_clients:1 client_recent_max_input_buffer:2 client_recent_max_output_buffer:0 blocked_clients:0 # Memory used_memory:854712 used_memory_human:834.68K used_memory_rss:14577664 used_memory_rss_human:13.90M used_memory_peak:854712 used_memory_peak_human:834.68K used_memory_peak_perc:100.15% used_memory_overhead:841206 used_memory_startup:791400 used_memory_dataset:13506 used_memory_dataset_perc:21.33% allocator_allocated:1053624 allocator_active:1257472 allocator_resident:8253440 total_system_memory:1968574464 total_system_memory_human:1.83G used_memory_lua:37888 used_memory_lua_human:37.00K used_memory_scripts:0 used_memory_scripts_human:0B number_of_cached_scripts:0 maxmemory:0 maxmemory_human:0B maxmemory_policy:noeviction allocator_frag_ratio:1.19 allocator_frag_bytes:203848 allocator_rss_ratio:6.56 allocator_rss_bytes:6995968 rss_overhead_ratio:1.77 rss_overhead_bytes:6324224 mem_fragmentation_ratio:17.94 mem_fragmentation_bytes:13765200 mem_not_counted_for_evict:0 mem_replication_backlog:0 mem_clients_slaves:0 mem_clients_normal:49694 mem_aof_buffer:0 mem_allocator:jemalloc-5.1.0 active_defrag_running:0 lazyfree_pending_objects:0 # Persistence loading:0 rdb_changes_since_last_save:1 rdb_bgsave_in_progress:0 rdb_last_save_time:1562476071 rdb_last_bgsave_status:ok rdb_last_bgsave_time_sec:0 rdb_current_bgsave_time_sec:-1 rdb_last_cow_size:4313088 aof_enabled:0 aof_rewrite_in_progress:0 aof_rewrite_scheduled:0 aof_last_rewrite_time_sec:-1 aof_current_rewrite_time_sec:-1 aof_last_bgrewrite_status:ok aof_last_write_status:ok aof_last_cow_size:0 # Stats total_connections_received:4 total_commands_processed:15 instantaneous_ops_per_sec:0 total_net_input_bytes:657 total_net_output_bytes:23425 instantaneous_input_kbps:0.00 instantaneous_output_kbps:0.00 rejected_connections:0 sync_full:0 sync_partial_ok:0 sync_partial_err:0 expired_keys:0 expired_stale_perc:0.00 expired_time_cap_reached_count:0 evicted_keys:0 keyspace_hits:2 keyspace_misses:0 pubsub_channels:0 pubsub_patterns:0 latest_fork_usec:12577 migrate_cached_sockets:0 slave_expires_tracked_keys:0 active_defrag_hits:0 active_defrag_misses:0 active_defrag_key_hits:0 active_defrag_key_misses:0 # Replication role:master connected_slaves:0 master_replid:51f70948dc66308f7ed0033888597c88b2e7955e master_replid2:0000000000000000000000000000000000000000 master_repl_offset:0 second_repl_offset:-1 repl_backlog_active:0 repl_backlog_size:1048576 repl_backlog_first_byte_offset:0 repl_backlog_histlen:0 # CPU used_cpu_sys:17.261375 used_cpu_user:18.492188 used_cpu_sys_children:0.007998 used_cpu_user_children:0.000000 # Cluster cluster_enabled:0 # Keyspace db0:keys=2,expires=0,avg_ttl=0 127.0.0.1:6379>
