{"id":26149,"date":"2022-06-26T11:50:29","date_gmt":"2022-06-26T01:50:29","guid":{"rendered":"https:\/\/database.guide\/?p=26149"},"modified":"2022-06-27T11:55:33","modified_gmt":"2022-06-27T01:55:33","slug":"redis-persist-command-explained","status":"publish","type":"post","link":"https:\/\/database.guide\/redis-persist-command-explained\/","title":{"rendered":"Redis PERSIST Command Explained"},"content":{"rendered":"\n

The Redis PERSIST<\/code> command removes any existing timeout on a given key. It returns an integer reply of 1<\/code> if the timeout was removed, or 0<\/code> if the key doesn’t exist or doesn’t have an associated timeout.<\/p>\n\n\n\n\n\n\n\n

Syntax<\/h2>\n\n\n\n

The syntax goes like this:<\/p>\n\n\n\n

PERSIST key<\/code><\/pre>\n\n\n\n
Where key<\/code> is the key for which to remove the expiry.<\/p>\n\n\n\n
Example<\/h2>\n\n\n\n
Suppose we set a key with an expiry:<\/p>\n\n\n\n
SET lunch \"Salad\" EX 86400<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
OK<\/pre>\n\n\n\n
Here, I used the EX<\/code> argument of the SET<\/a><\/code> command to set an expiry in seconds. <\/p>\n\n\n\n
Now let’s check the key’s time to live:<\/p>\n\n\n\n
TTL lunch<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
(integer) 86349<\/pre>\n\n\n\n
There is still plenty of time before this key expires.<\/p>\n\n\n\n
In Redis 7.0.0 and higher, we can also use the EXPIRETIME<\/a><\/code> command to check the absolute Unix time that it will expire:<\/p>\n\n\n\n
EXPIRETIME lunch<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
(integer) 1655961287<\/pre>\n\n\n\n
OK, now let’s use the PERSIST<\/code> command to remove the expiry associated with the key:<\/p>\n\n\n\n
PERSIST lunch<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
(integer) 1<\/pre>\n\n\n\n
We get an integer reply of 1<\/code>, which means the expiry was removed.<\/p>\n\n\n\n
Now when we use the TTL<\/code> command, we get -1<\/code>:<\/p>\n\n\n\n
TTL lunch<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
(integer) -1<\/pre>\n\n\n\n
This means that the key exists, but doesn’t have an expiry.<\/p>\n\n\n\n
When the Key Has No Expiry<\/h2>\n\n\n\n
If the key has no expiry, PERSIST<\/code> returns 0<\/code>.<\/p>\n\n\n\n
To test this, let’s run PERSIST<\/code> against the same key, now that we’ve removed its timeout:<\/p>\n\n\n\n
PERSIST lunch<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
(integer) 0<\/pre>\n\n\n\n
As expected.<\/p>\n\n\n\n
When the Key Doesn’t Exist<\/h2>\n\n\n\n
If the key doesn’t exist, PERSIST<\/code> returns 0<\/code>. To test this, let’s delete the key, and then run PERSIST<\/code> against it.<\/p>\n\n\n\n
Delete the key:<\/p>\n\n\n\n
DEL lunch<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
(integer) 1<\/pre>\n\n\n\n
This means that the key was deleted.<\/p>\n\n\n\n
Now let’s run PERSIST<\/code> against it:<\/p>\n\n\n\n
PERSIST lunch<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
(integer) 0<\/pre>\n\n\n\n
As expected, we get an integer reply of 0<\/code>.<\/p>\n","protected":false},"excerpt":{"rendered":"
The Redis PERSIST command removes any existing timeout on a given key. It returns an integer reply of 1 if the timeout was removed, or 0 if the key doesn’t exist or doesn’t have an associated timeout.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[153],"tags":[154,20],"class_list":["post-26149","post","type-post","status-publish","format-standard","hentry","category-redis","tag-commands","tag-what-is"],"_links":{"self":[{"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/posts\/26149","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=26149"}],"version-history":[{"count":4,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/posts\/26149\/revisions"}],"predecessor-version":[{"id":26228,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/posts\/26149\/revisions\/26228"}],"wp:attachment":[{"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/media?parent=26149"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/categories?post=26149"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/tags?post=26149"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}