The command returns the stream entries matching a given range of IDs. The range is specified by a minimum and maximum ID. All the entries having an ID between the two specified or exactly one of the two IDs specified (closed interval) are returned. The `XRANGE` command has a number of applications: * Returning items in a specific time range. This is possible because Stream IDs are [related to time](/topics/streams-intro). * Iterating a stream incrementally, returning just a few items at every iteration. However it is semantically much more robust than the `SCAN` family of functions. * Fetching a single entry from a stream, providing the ID of the entry to fetch two times: as start and end of the query interval. The command also has a reciprocal command returning items in the reverse order, called `XREVRANGE`, which is otherwise identical. ## `-` and `+` special IDs The `-` and `+` special IDs mean respectively the minimum ID possible and the maximum ID possible inside a stream, so the following command will just return every entry in the stream: ``` > XRANGE somestream - + 1) 1) 1526985054069-0 2) 1) "duration" 2) "72" 3) "event-id" 4) "9" 5) "user-id" 6) "839248" 2) 1) 1526985069902-0 2) 1) "duration" 2) "415" 3) "event-id" 4) "2" 5) "user-id" 6) "772213" ... other entries here ... ``` The `-` ID is effectively just exactly as specifying `0-0`, while `+` is equivalent to `18446744073709551615-18446744073709551615`, however they are nicer to type. ## Incomplete IDs Stream IDs are composed of two parts, a Unix millisecond time stamp and a sequence number for entries inserted in the same millisecond. It is possible to use `XRANGE` specifying just the first part of the ID, the millisecond time, like in the following example: ``` > XRANGE somestream 1526985054069 1526985055069 ``` In this case, `XRANGE` will auto-complete the start interval with `-0` and end interval with `-18446744073709551615`, in order to return all the entries that were generated between a given millisecond and the end of the other specified millisecond. This also means that repeating the same millisecond two times, we get all the entries within such millisecond, because the sequence number range will be from zero to the maximum. Used in this way `XRANGE` works as a range query command to obtain entries in a specified time. This is very handy in order to access the history of past events in a stream. ## Exclusive ranges The range is close (inclusive) by default, meaning that the reply can include entries with IDs matching the query's start and end intervals. It is possible to specify an open interval (exclusive) by prefixing the ID with the character `(`. This is useful for iterating the stream, as explained below. ## Returning a maximum number of entries Using the **COUNT** option it is possible to reduce the number of entries reported. This is a very important feature even if it may look marginal, because it allows, for instance, to model operations such as *give me the entry greater or equal to the following*: ``` > XRANGE somestream 1526985054069-0 + COUNT 1 1) 1) 1526985054069-0 2) 1) "duration" 2) "72" 3) "event-id" 4) "9" 5) "user-id" 6) "839248" ``` In the above case the entry `1526985054069-0` exists, otherwise the server would have sent us the next one. Using `COUNT` is also the base in order to use `XRANGE` as an iterator. ## Iterating a stream In order to iterate a stream, we can proceed as follows. Let's assume that we want two elements per iteration. We start fetching the first two elements, which is trivial: ``` > XRANGE writers - + COUNT 2 1) 1) 1526985676425-0 2) 1) "name" 2) "Virginia" 3) "surname" 4) "Woolf" 2) 1) 1526985685298-0 2) 1) "name" 2) "Jane" 3) "surname" 4) "Austen" ``` Then instead of starting the iteration again from `-`, as the start of the range we use the entry ID of the *last* entry returned by the previous `XRANGE` call as an exclusive interval. The ID of the last entry is `1526985685298-0`, so we just prefix it with a '(', and continue our iteration: ``` > XRANGE writers (1526985685298-0 + COUNT 2 1) 1) 1526985691746-0 2) 1) "name" 2) "Toni" 3) "surname" 4) "Morrison" 2) 1) 1526985712947-0 2) 1) "name" 2) "Agatha" 3) "surname" 4) "Christie" ``` And so forth. Eventually this will allow to visit all the entries in the stream. Obviously, we can start the iteration from any ID, or even from a specific time, by providing a given incomplete start ID. Moreover, we can limit the iteration to a given ID or time, by providing an end ID or incomplete ID instead of `+`. The command `XREAD` is also able to iterate the stream. The command `XREVRANGE` can iterate the stream reverse, from higher IDs (or times) to lower IDs (or times). ### Iterating with earlier versions of Redis While exclusive range intervals are only available from Redis 6.2, it is still possible to use a similar stream iteration pattern with earlier versions. You start fetching from the stream the same way as described above to obtain the first entries. For the subsequent calls, you'll need to programmatically advance the last entry's ID returned. Most Redis client should abstract this detail, but the implementation can also be in the application if needed. In the example above, this means incrementing the sequence of `1526985685298-0` by one, from 0 to 1. The second call would, therefore, be: ``` > XRANGE writers 1526985685298-1 + COUNT 2 1) 1) 1526985691746-0 2) 1) "name" 2) "Toni" ... ``` Also, note that once the sequence part of the last ID equals 18446744073709551615, you'll need to increment the timestamp and reset the sequence part to 0. For example, incrementing the ID `1526985685298-18446744073709551615` should result in `1526985685299-0`. A symmetrical pattern applies to iterating the stream with `XREVRANGE`. The only difference is that the client needs to decrement the ID for the subsequent calls. When decrementing an ID with a sequence part of 0, the timestamp needs to be decremented by 1 and the sequence set to 18446744073709551615. ## Fetching single items If you look for an `XGET` command you'll be disappointed because `XRANGE` is effectively the way to go in order to fetch a single entry from a stream. All you have to do is to specify the ID two times in the arguments of XRANGE: ``` > XRANGE mystream 1526984818136-0 1526984818136-0 1) 1) 1526984818136-0 2) 1) "duration" 2) "1532" 3) "event-id" 4) "5" 5) "user-id" 6) "7782813" ``` ## Additional information about streams For further information about Redis streams please check our [introduction to Redis Streams document](/topics/streams-intro). @return @array-reply, specifically: The command returns the entries with IDs matching the specified range. The returned entries are complete, that means that the ID and all the fields they are composed are returned. Moreover, the entries are returned with their fields and values in the exact same order as `XADD` added them. @examples ```cli XADD writers * name Virginia surname Woolf XADD writers * name Jane surname Austen XADD writers * name Toni surname Morrison XADD writers * name Agatha surname Christie XADD writers * name Ngozi surname Adichie XLEN writers XRANGE writers - + COUNT 2 ```