第 9 章：数据库

数据库示例。

digraph { label = "\n 图 9-1 服务器数据库示例"; rankdir = LR; node [shape = record]; // redisServer [label = "redisServer | ... | <db> db | ... | dbnum \n 16 | ..."]; db [label = "{ <0> db[0] | <1> db[1] | <2> db[2] | ... | <15> db[15] }"]; // redisServer:db -> db; }

数据库键空间示例。

digraph { label = "\n图 9-4 数据库键空间例子"; rankdir = LR; node [shape = record]; // redisDb [label = "redisDb | ... | <dict> dict | ..."]; dict [label = "<dict> dict | <alphabet> StringObject \n \"alphabet\" | <book> StringObject \n \"book\" | <message> StringObject \n \"message\""]; subgraph cluster_alphabet { a [label = " StringObject \n \"a\" "]; b [label = " StringObject \n \"b\" "]; c [label = " StringObject \n \"c\" "]; a -> b -> c; label = "ListObject"; } //alphabet [label = "<head> ListObject | { StringObject \n \"a\" | \"b\" | \"c\" }"]; book [label = "<head> HashObject | <name> StringObject \n \"name\" | <author> StringObject \n \"author\" | <publisher> StringObject \n \"publisher\""]; //name [label = " StringObject \n \"Redis in Action\""]; name [label = " StringObject \n \"Redis in Action\""]; author [label = " StringObject \n \"Josiah L. Carlson\""]; publisher [label = " StringObject \n \"Manning\""]; message [label = " StringObject \n \"hello world\""]; // redisDb:dict -> dict:dict; dict:alphabet -> a; dict:book -> book:head; dict:message -> message; book:name -> name; book:publisher -> publisher; book:author -> author; }

带有过期时间的字典示例。

digraph { label = "\n图 9-12 带有过期字典的数据库例子"; rankdir = LR; node [shape = record]; // redisDb [label = "redisDb | ... | <dict> dict | <expires> expires | ..."]; dict [label = "<dict> dict | <alphabet> StringObject \n \"alphabet\" | <book> StringObject \n \"book\" | <message> StringObject \n \"message\""]; subgraph cluster_alphabet { a [label = " StringObject \n \"a\" "]; b [label = " StringObject \n \"b\" "]; c [label = " StringObject \n \"c\" "]; a -> b -> c; label = "ListObject"; } book [label = "<head> HashObject | <name> StringObject \n \"name\" | <author> StringObject \n \"author\" | <publisher> StringObject \n \"publisher\""]; name [label = "<head> StringObject \n \"Redis in Action\""]; author [label = "<head> StringObject \n \"Josiah L. Carlson\""]; publisher [label = "<head> StringObject \n \"Manning\""]; message [label = "<head> StringObject \n \"hello world\""]; // expires [label = "<head> dict | <alphabet> StringObject \n \"alphabet\" | <book> StringObject \n \"book\""]; redisDb:expires -> expires:head; alphabet_expire [label = "<head> long long | 1385877600000"]; book_expire [label = "<head> long long | 1388556000000"]; expires:alphabet -> alphabet_expire:head; expires:book -> book_expire:head; // redisDb:dict -> dict:dict; dict:alphabet -> a; dict:book -> book:head; dict:message -> message:head; book:name -> name:head; book:publisher -> publisher:head; book:author -> author:head; }

GET 命令判断是否需要删除过期键的过程。

digraph { label = "\n图 9-16 GET 命令的执行过程"; node [shape = box]; // get [label = "GET <key>"]; key_exists_or_not [label = "键不存在？", shape = diamond]; key_expired_or_not [label = "键已过期？", shape = diamond]; return_nil [label = "返回空回复"]; return_value [label = "返回键 key 的值"]; // get -> key_exists_or_not; key_exists_or_not -> return_nil [label = "是"]; key_exists_or_not -> key_expired_or_not [label = "否"]; key_expired_or_not -> return_nil [label = "是\n删除过期键"]; key_expired_or_not -> return_value [label = "否"]; }

当 Redis 运行在复制模式时， 主从服务器处理过期键的流程。

digraph { label = "\n图 9-17 主从服务器删除过期键 （1）"; rankdir = LR; // node [shape = record]; subgraph cluster_master { label = "主服务器"; master_db [label = " 数据库 | message \n （已过期） | xxx | yyy "]; } subgraph cluster_slave { label = "从服务器"; slave_db [label = " 数据库 | message \n （已过期） | xxx | yyy "]; } // master_db -> slave_db [style = invis, minlen = 2]; }
digraph { label = "\n图 9-18 主从服务器删除过期键 （2）"; rankdir = LR; // node [shape = record]; subgraph cluster_master { label = "主服务器"; master_db [label = " 数据库 | message \n （已过期） | xxx | yyy "]; } subgraph cluster_slave { label = "从服务器"; slave_db [label = " 数据库 | <message> message \n （已过期） | xxx | yyy "]; } client [label = "客户端", shape = circle]; // splines = polyline; master_db -> slave_db [style = invis, minlen = 2]; slave_db -> client [dir = back, label = "GET message"]; slave_db -> client [label = "(nil)"]; }
digraph { label = "\n图 9-19 主从服务器删除过期键 （3）"; rankdir = LR; // node [shape = record]; subgraph cluster_master { label = "主服务器"; master_db [label = " 数据库 | xxx | yyy ", width = 1.25, height = 1.75]; } subgraph cluster_slave { label = "从服务器"; slave_db [label = " 数据库 | <message> message \n （已过期） | xxx | yyy "]; } client [label = "客户端", shape = circle]; // splines = polyline; master_db -> slave_db [label = "DEL message"]; client -> master_db [label = "GET message"]; client -> master_db [dir = back, label = "(nil)"]; }
digraph { label = "\n图 9-20 主从服务器删除过期键 （4）"; rankdir = LR; // node [shape = record, width = 1.25, height = 1.75]; subgraph cluster_master { label = "主服务器"; master_db [label = " 数据库 | xxx | yyy "]; } subgraph cluster_slave { label = "从服务器"; slave_db [label = " 数据库 | xxx | yyy "]; } // master_db -> slave_db [style = invis, minlen = 2]; }