Transactions in Redis

Redis supports simple transactions

Comparison of Redis and MySQL transactions

	mysql	redis
turn on	starttransaction	muitl
statement	General sql	General Command
failed	rollback rollback	discard cancel
Success	Commit	Exec

Note : The difference between rollback and discard

• If you have successfully executed 2 statements , the 3 statement has an error .
• After the rollback, the first 2 statements affect the disappearance .
• Discard only ends this transaction , the impact of the first 2 statements is still

Note :

In the statement that follows Mutil , there may be 2 cases of error in the statement

1. There's a problem with grammar .

This , exec , error , all statements are not executed

2. The syntax itself is correct, but there are problems with the object . For example, Zadd manipulating the list object

< Span lang= "en-us" >exec after

(If zadd operations list How to avoid it ? This , the programmer is responsible for ) requires the programmer to manually control the operation

Thinking :

I was buying a ticket.

Ticket-1, money-100

1 Zhang If I multi after exec before tickets bought by others ---namely ticket into 0

How to observe this situation and no longer submit

A pessimistic idea :

The World is full of danger, it must be someone and I Rob , to ticket lock , only I can operate . [Pessimistic lock ]

An optimistic idea :

Not so people and I Rob , therefore , I just need to note that

--No one can change the value of the ticket. [optimistic lock ]

In the Redis transaction , the optimistic lock is enabled and only the monitoring key is not altered .

Specific command ----Watch command

Example :

Redis127.0.0.1:6379>Watch Ticketokredis127.0.0.1:6379>Multiokredis127.0.0.1:6379>DECR Ticketqueuedredis127.0.0.1:6379> Decrby Money -Queuedredis127.0.0.1:6379>exec (nil)//returns nil, indicating that the ticket of the watch has changed and the transaction is canceled.Redis127.0.0.1:6379>GetTicket"0"Redis127.0.0.1:6379>Get Money" $"

Watchkey1 Key2 ... KeyN

Role : Monitor key1key2. Keyn There are no changes, if there is a change , then the transaction is canceled

Unwatch

function : Cancels all watch monitoring

Transactions in Redis