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![Keys *
di = dictGetSafeIterator(c->db->dict);
allkeys = (pattern[0] == '*' && pattern[1] == '0');
while((de = dictNext(di)) != NULL) {
……
stringmatchlen(pattern,plen,key,sdslen(key),0)
}](https://image.slidesharecdn.com/redisbegins-130711083749-phpapp01/85/Redis-begins-19-320.jpg)
![FlushAll-Redis
for (i = 0; i < ht->size && ht->used > 0; i++) {
dictEntry *he, *nextHe;
if ((he = ht->table[i]) == NULL) continue;
while(he) {
nextHe = he->next;
dictFreeKey(d, he);
dictFreeVal(d, he);
zfree(he);
ht->used--;
he = nextHe;
}
}](https://image.slidesharecdn.com/redisbegins-130711083749-phpapp01/85/Redis-begins-23-320.jpg)
Uploaded byDaeMyung Kang
Redis begins
Redis is an open source, advanced key-value store. It supports data structures like lists, sets, sorted sets, and hashes. Redis can persist data on disk using Redis Database files or append-only files. Redis supports master-slave replication where slaves can be promoted to masters in case of failures using Redis Sentinel. The main thing to note is that Redis is single-threaded, so long operations can block the server.
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Redis begins
- 1.
- 2.
- 3. Redis? Redis is anopen source. http://redis.io
- 4. Redis? Redis is anopen source. BSD licensed. http://redis.io
- 5. Redis? Redis is anopen source. BSD licensed. advanced key-value store. http://redis.io
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- 10. But You can meetsome errors in Linux Solution: $> make distclean; make;
- 11. Why? Redis saves settingsto .make-* files And they disturb normal building.
- 12.
- 13. The one thing youshould know.
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- 19. Keys * di =dictGetSafeIterator(c->db->dict); allkeys = (pattern[0] == '*' && pattern[1] == '0'); while((de = dictNext(di)) != NULL) { …… stringmatchlen(pattern,plen,key,sdslen(key),0) }
- 20. FlushAll Cache Item CountTime Memcache 1,000,000 1~2ms Redis 1,000,000 1000ms(1 second)
- 21. Memcache’s flush is fasterthan Redis’s flush.
- 22. Memcache’s flush is fasterthan Redis’s flush?
- 23. FlushAll-Redis for (i =0; i < ht->size && ht->used > 0; i++) { dictEntry *he, *nextHe; if ((he = ht->table[i]) == NULL) continue; while(he) { nextHe = he->next; dictFreeKey(d, he); dictFreeVal(d, he); zfree(he); ht->used--; he = nextHe; } }
- 24. FlushAll-Memcache if (exptime >0) settings.oldest_live = realtime(exptime) - 1; else /* exptime == 0 */ settings.oldest_live = current_time - 1;
- 25. FlushAll-Memcache if (settings.oldest_live !=0 && settings.oldest_live <= current_time && it->time <= settings.oldest_live) { do_item_unlink(it, hv); do_item_remove(it); it = NULL; }
- 26.
- 27. Collections Memcached supports justK-V List Set Sorted Set Hash
- 28. Key:Value $> set keyvalue $> get key
- 29. Key:Value sql> insert intouserinfo (name, email) values(‘charsyam’, ‘test@abc.com’);
- 30. Key:Value $> set id:name“charsyam” $> set id:email test@abc.com $> mget id:name id:email 1) “charsyam” 2) test@abc.com”
- 31. List $> rpush listnamea --- (a) $> rpush listname b --- (a, b) $> lpush listname c --- (c, a, b) $> rpop listname(or lpop listname)
- 32. List - when Whenyou need job queue or stack.
- 33. Set $> sadd setnameid1 $> sadd setname id2 $> smember setname 1) “id2” 2) “id1”
- 34. set - when Whenyou need follwers ids or group members id
- 35. Sorted Set $> zaddzsetname 1 “one” $> zadd zsetname 2 “two” $> zadd zsetname 3 “three”
- 36. Sorted Set $> zrangezsetname 0 -1 1) “one” 2) “two” 3) “three”
- 37. zset - when Whenyou need ranking
- 38. Sorted Set $> zrangezsetname 1 3 1) “two” 2) “three”
- 39. Hash sql> insert intouserinfo (name, email) values(‘charsyam’, ‘test@abc.com’);
- 40. Hash$> hmset idname “charsyam” email test@abc.com
- 41. Hash$> hgetall 1) “name” 2)“charsyam” 3) “email” 4) “test@abc.com”
- 42. Hash$> hset idemail abc@abc.com $> hgetall 1) “name” 2) “charsyam” 3) “email” 4) “abc@abc.com”
- 43.
- 44. The one thing youshould know.
- 45.
- 46. Don’t insert too manyitems into collections.
- 47. Delete collections Item CountTime list 1,000,000 1000ms(1 second) set Sorted set hash
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- 49. Redis can store itsmemory snapshot.
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- 51. RDB is not RelationDBMS.
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- 53.
- 54. RDB - BAD •Bad Performance in Large memory. • Twice memory problem. • Denying write problem when storing RDB fails. • If you just want Cache. Turn off RDB
- 55. RDB – LargeMemory • Performance is relevant to Memory Size. 17.1 GB 34.2 GB 68.4 GB 117 GB
- 56. RDB – TwiceMemory • fork() and COW(copy on write) Issue –In Write Heavy System:
- 57. RDB – TwiceMemory
- 58. RDB – TwiceMemory
- 59. RDB – TwiceMemory
- 60. Real Case Study •Background –Can’t write to Redis Server –Sentinel doesn’t find Server’s failure.
- 61. Real Case Study •Reason –If redis fails to save RDB, Redis basically denies write operations from client. –“MISCONF Redis is configured to save RDB snapshots, but is currently not able to persist on disk. Commands that may modify the data set are disabled. Please check Redis logs for details about the error.”
- 62. Real Case Study •Reason if (server.stop_writes_on_bgsave_err && server.saveparamslen > 0 && server.lastbgsave_status == REDIS_ERR && c->cmd->flags & REDIS_CMD_WRITE) { flagTransaction(c); addReply(c, shared.bgsaveerr); return REDIS_OK; }
- 63. Real Case Study •Solution #1 • Solution #2 config set stop-writes-on-bgsave-error no Turn off RDB Setting 2.6.12 부터 conf 에서 stop-writes-on-bgsave-error 설정이 가능해짐.
- 64.
- 65. AOF is append onlyfile.
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- 69. AOF Rewrite When sizeof AOF grows than redis rewrite memory state to AOF.
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- 72. Replication •Support Chained Replication Master1st Slave 2nd Slave 1st slave is master of 2nd slave
- 73.
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- 75. Replication Master Slave replicationCron When masterreruns, Resync with Master
- 76. Mistake: Replication Master Slave replicationCron Slavewill has no data after resyncing If master has no data.
- 77.
- 78.
- 79.
- 80. Sentinel • Sentinel isFailover Solution for Redis. Master Slave Sentinel Sentinel periodically checks Redis Master
- 81. Sentinel Master Slave Sentinel Send “slaveofno one” to slave node
- 82. Sentinel Master Slave Sentinel Notify toclient about changing master Client
- 83. Sentinel redis 127.0.0.1:2003> psubscribe* Reading messages... (press Ctrl-C to quit) 1) "pmessage" 2) "*" 3) "+switch-master" 4) "resque 127.0.0.1 1999 127.0.0.1 2002"
- 84. Sentinel • Sentinel willconnect correct master even if you set slave’s ip in conf Master Slave Sentinel Slave’s ip in sentinel.conf
- 85.
- 86. Sentinel • Reconnect tocorrect master using master_host and master_port. Master Slave Sentinel Reconnect to master of slave.
- 87. Sentinel.conf port 26379 sentinel monitormymaster 127.0.0.1 6379 1 sentinel down-after-milliseconds mymaster 30000 sentinel can-failover mymaster yes sentinel parallel-syncs mymaster 1 sentinel failover-timeout mymaster 900000
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