Shulou(Shulou.com)06/01 Report--

There are two ways to persist Redis: 1 snapshot 2 is a log

Configuration options for Rdb snapshots (snapshots in memory are written to disk faster)

Configuration file:

1 write within 900s of save 9001 / 900s, then a snapshot is generated

Save 1000 / / if there are 1000 writes in 300 seconds, a snapshot is generated

Save 60 10000 / / if there are 10000 writes in 60 seconds, a snapshot is generated

(if all three options are masked, rdb is disabled)

When there is an error in the stop-writes-on-bgsave-error yes / / background backup process, does the main process stop writing?

Whether the exported rdb file of rdbcompression yes / / is compressed

Rdbchecksum yes / / when importing rbd recovery data, do you want to verify the integrity of rdb?

Dbfilename dump.rdb / / exported rdb file name

The placement path of dir. / rdb

Configuration of Aof

Appendonly no # whether to turn on aof logging function

Appendfsync always # every command is immediately synchronized to aof. Safe, slow

Appendfsync everysec # compromise, write once per second

Appendfsync no # write work to the operating system, the operating system to determine the size of the buffer, unified write to aof. Low synchronization frequency and high speed

No-appendfsync-on-rewrite yes: # do you want to stop synchronizing aof while exporting rdb snapshots?

Auto-aof-rewrite-percentage 100 # aof file size compared to the size of the last rewrite, when the growth rate is 100%, rewrite

Auto-aof-rewrite-min-size 64mb # aof file, overridden when it exceeds at least 64m

Note: will aof be lost if it stops synchronization during dump rdb?

Answer: no, all operations are cached in the memory queue. After the dump is completed, the operation will be unified.

Note: what is aof rewriting?

A: aof rewriting refers to the data in memory, inverted into commands, and written to the .aof log.

To solve the problem that aof log is too large.

Q: if both rdb files and aof files exist, who is the priority to restore data?

A: aof

Q: can the two be used at the same time?

A: yes, and it is recommended

Q: which is faster to recover, rdb or aof?

Answer: rdb is fast, because it is a memory map of data and is directly loaded into memory, while aof is a command that needs to be executed one by one.

Redis server-side command

Redis 127.0.0.1 6380 > time, showing server time, timestamp (seconds), and microseconds

1) "1375270361"

2) "504511"

Redis 127.0.0.1 key 6380 > dbsize / / number of current database key

(integer) 2

Redis 127.0.0.1 6380 > select 2

OK

Redis 127.0.0.1 redis [2] > dbsize

(integer) 0

Redis 127.0.0.1 6380 [2] >

The BGREWRITEAOF background process overrides AOF

BGSAVE background saves rdb Snapshot

SAVE saves rdb Snapshot

Last saved time of LASTSAVE

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