`|Redis Documentation| <index.html>`_
**SetrangeCommand: Contents**
  `SETRANGE \_key\_ \_offset\_ \_value\_ (Redis > <#SETRANGE%20_key_%20_offset_%20_value_%20(Redis%20%3E>`_
    `Examples <#Examples>`_
    `Patterns <#Patterns>`_
    `Return value <#Return%20value>`_
SetrangeCommand
===============

#sidebar `StringCommandsSidebar <StringCommandsSidebar.html>`_
SETRANGE \_key\_ \_offset\_ \_value\_ (Redis >
==============================================

2.1.8) =
*Time complexity: O(1) not counting the time taken to copy the new string in place, as usually this string is small so the amoritzed time is O(1). Otheriwse O(M) with M being the length of the value argument*
    Overwrites part of a string at *key* starting at the specified
    offset,for all the length of *value*.If the offset is over the old
    length of the string, the string is paddedwith zero bytes until
    needed. Non existing keys are considered likealready containing an
    empty string.

Examples
--------

First example, basic usage setting a range.
::

    redis> set foo "Hello World"
    OK
    redis> setrange foo 6 "Redis"
    (integer) 11
    redis> get foo
    "Hello Redis"

Example of the zero padding behavior.
::

    redis> del foo
    (integer) 1
    redis> setrange foo 10 bar
    (integer) 13
    redis> get foo
    "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00bar"

Note that the maximum offset that you can set is 536870911 as Redis
Strings are limited to 512 megabytes. You can still create longer
arrays of values using multiple keys.
**Warning**: When setting the last possible byte and the string
value stored at *key* does not yet hold a string value, or holds a
small string value, Redis needs to allocate all intermediate memory
which can block the server for some time. On a 2010 Macbook Pro,
setting byte number 536870911 (512MB allocation) takes ~300ms,
setting byte number 134217728 (128MB allocation) takes ~80ms,
setting bit number 33554432 (32MB allocation) takes ~30ms and
setting bit number 8388608 (8MB allocation) takes ~8ms. Note that
once this first allocation is done, subsequent calls to SETRANGE
for the same *key* will not have the allocation overhead.
Patterns
--------

Thanks to SETRANGE and the analogous GETRANGE command you can use
Redis strings as a linear array of memory with O(1) random access.
This is a very fast and efficient storage in many real world use
cases.
Return value
------------

`Integer reply <ReplyTypes.html>`_, specifically: the length of the
string after it was modified by the command.
.. |Redis Documentation| image:: redis.png