{"id":25970,"date":"2022-06-27T12:02:00","date_gmt":"2022-06-27T02:02:00","guid":{"rendered":"https:\/\/database.guide\/?p=25970"},"modified":"2022-06-27T12:02:00","modified_gmt":"2022-06-27T02:02:00","slug":"redis-incrby-command-explained","status":"publish","type":"post","link":"https:\/\/database.guide\/redis-incrby-command-explained\/","title":{"rendered":"Redis INCRBY Command Explained"},"content":{"rendered":"\n

In Redis, the INCRBY<\/code> command increments the value of a key by the specified amount.<\/p>\n\n\n\n

If the key doesn’t exist, INCRBY<\/code> creates the key with a value of 0<\/code> and then increments it by the specified amount.<\/p>\n\n\n\n

An error occurs if the key contains a value of the wrong type or contains a string that cannot be represented as integer. INCRBY<\/code> operations are limited to 64 bit signed integers.<\/p>\n\n\n\n\n\n\n\n

Syntax<\/h2>\n\n\n\n
INCRBY key increment<\/code><\/pre>\n\n\n\n
Where key<\/em><\/code> is the key to increment, and increment<\/code><\/em> is the amount to increment it by.<\/p>\n\n\n\n
Example<\/h2>\n\n\n\n
Suppose we set a key like this:<\/p>\n\n\n\n
SET score \"10\"<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
OK<\/pre>\n\n\n\n
Let’s quickly take a look at it:<\/p>\n\n\n\n
GET score<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
\"10\"<\/pre>\n\n\n\n
OK, now let’s increment it by seven:<\/p>\n\n\n\n
INCRBY score 7<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
(integer) 17<\/pre>\n\n\n\n
We get an integer reply with the value of the key after the INCRBY<\/code> operation was performed.<\/p>\n\n\n\n
Let’s run the GET<\/a><\/code> command again:<\/p>\n\n\n\n
GET score<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
\"17\"<\/pre>\n\n\n\n
As expected, the original value of 10 has been incremented by 7.<\/p>\n\n\n\n
Negative Values<\/h2>\n\n\n\n
Redis does not have a dedicated integer type. However, the string stored at the key is interpreted as a base-10 64 bit signed integer to execute the operation. Therefore, we can increment negative values just as we can increment positive values.<\/p>\n\n\n\n
Set a negative value:<\/p>\n\n\n\n
SET score \"-10\"<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
OK<\/pre>\n\n\n\n
Let’s quickly take a look at it:<\/p>\n\n\n\n
GET score<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
\"-10\"<\/pre>\n\n\n\n
OK, now let’s increment it by seven:<\/p>\n\n\n\n
INCRBY score 7<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
(integer) -3<\/pre>\n\n\n\n
The value has been incremented by seven.<\/p>\n\n\n\n
We can check this at any time by running the GET<\/code> command again:<\/p>\n\n\n\n
GET score<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
\"-3\"<\/pre>\n\n\n\n
We can also increment it by a negative amount, which has the effect of decrementing the value:<\/p>\n\n\n\n
INCRBY score -7<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
(integer) -10<\/pre>\n\n\n\n
We can also use the DECR<\/code> and DECRBY<\/code> commands to decrement values.<\/p>\n\n\n\n
When the Key Doesn’t Exist<\/h2>\n\n\n\n
If the key doesn’t exist, INCRBY<\/code> creates the key with a value of 0<\/code> and then increments it by the specified amount.<\/p>\n\n\n\n
Let’s delete our score<\/code> key:<\/p>\n\n\n\n
DEL score<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
(integer) 1<\/pre>\n\n\n\n
The DEL<\/code> command returns the number of keys that were deleted – in this case 1.<\/p>\n\n\n\n
Now let’s try to increment that (non-existent) key:<\/p>\n\n\n\n
INCRBY score 10<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
(integer) 10<\/pre>\n\n\n\n
So we can see that score<\/code> has been recreated with a value of 10.<\/p>\n\n\n\n
When the Value is the Wrong Type<\/h2>\n\n\n\n
An error occurs if the key contains a value of the wrong type or contains a string that cannot be represented as an integer.<\/p>\n\n\n\n
To test this, let’s try incrementing a value that can’t be represented as an integer.<\/p>\n\n\n\n
Set the amount:<\/p>\n\n\n\n
SET score \"Ten\"<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
OK<\/pre>\n\n\n\n
Let’s quickly take a look at it:<\/p>\n\n\n\n
GET score<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
\"Ten\"<\/pre>\n\n\n\n
OK, now let’s try to increment it by seven:<\/p>\n\n\n\n
INCRBY score 7<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
(error) ERR value is not an integer or out of range<\/pre>\n\n\n\n
An error occurred as expected.<\/p>\n\n\n\n
Increment by One<\/h2>\n\n\n\n
Although INCRBY<\/code> can be used to increment a key by one, there’s another command called INCR<\/code> that is designed to do exactly that. When using INCR<\/code>, you don’t need to specify the increment amount – you only need to specify the key.<\/p>\n\n\n\n
So the following:<\/p>\n\n\n\n
INCR score<\/code><\/pre>\n\n\n\n
Is the equivalent of this:<\/p>\n\n\n\n
INCRBY score 1<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
In Redis, the INCRBY command increments the value of a key by the specified amount. If the key doesn’t exist, INCRBY creates the key with a value of 0 and then increments it by the specified amount. An error occurs if the key contains a value of the wrong type or contains a string that … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[153],"tags":[154,84,20],"class_list":["post-25970","post","type-post","status-publish","format-standard","hentry","category-redis","tag-commands","tag-string","tag-what-is"],"_links":{"self":[{"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/posts\/25970","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/comments?post=25970"}],"version-history":[{"count":5,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/posts\/25970\/revisions"}],"predecessor-version":[{"id":26273,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/posts\/25970\/revisions\/26273"}],"wp:attachment":[{"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/media?parent=25970"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/categories?post=25970"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/tags?post=25970"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}