In Redis, the TTL command returns the remaining time to live of a given key, in seconds.
If the key doesn’t have a timeout, an integer reply of -1 is returned. If the key doesn’t exist, -2 is returned.
Redis also has a PTTL command, which works the same, but returns its result in milliseconds.
The Redis PEXPIRETIME command returns the absolute Unix timestamp in milliseconds at which the given key will expire. This is the number of milliseconds since 00:00:00 UTC on 1 January 1970 until the expiry time of the key.
This works exactly the same as EXPIRETIME, but it returns the Unix timestamp in milliseconds instead of seconds.
The PEXPIRETIME command was introduced in Redis 7.0.0.
The Redis EXPIRETIME command returns the absolute Unix timestamp in seconds at which the given key will expire. This is the number of seconds since 00:00:00 UTC on 1 January 1970 until the expiry time of the key.
The EXPIRETIME command was introduced in Redis 7.0.0.
Oracle Database supports the creation of generated columns. A generated column is a column whose value is derived from an expression that computes values from other columns.
In Oracle Database, generated columns are usually referred to as virtual columns. Generated columns can also be referred to as computed columns in other RDBMSs (such as SQL Server). Either way, they do pretty much the same thing – they contain an expression that computes a value based on values in other columns in the same table.
Continue readingThe Redis EXPIREAT command sets a timeout as a Unix timestamp on a given key. It works the same as the EXPIRE command, but with an absolute Unix timestamp instead of a time interval in seconds (which EXPIRE uses).
The Redis PEXPIREAT command sets a timeout as a Unix timestamp on a given key in milliseconds. It works the same as the EXPIREAT command, except that it sets the timeout in milliseconds instead of seconds.
It’s also similar to the PEXPIRE command, but with an absolute Unix timestamp instead of a time interval.
The Redis PEXPIRE command sets a timeout on a given key in milliseconds. After the timeout has expired, the key will be deleted.
The PEXPIRE command works exactly the same as the EXPIRE command, except that it returns the timeout in milliseconds instead of seconds.
The Redis EXPIRE command sets a timeout on a given key in seconds. After the timeout has expired, the key will be deleted.
Redis also has a PEXPIRE command that works the same as EXPIRE, except that it returns the timeout in milliseconds instead of seconds.
A key with a timeout is said to be volatile in Redis terminology.
Continue readingMost RDBMSs provide at least a few ways to return rows that contain uppercase characters. Here are some options available in the major RDBMSs.
Continue readingIn Redis, the STRLEN command returns the length of the string stored at a given key.