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Overwrites part of the string stored at _key_, starting at the specified offset,
for the entire length of _value_. If the offset is larger than the current
length of the string at _key_, the string is padded with zero-bytes to make
_offset_ fit. Non-existing keys are considered as empty strings, so this command
will make sure it holds a string large enough to be able to set _value_ at
_offset_.
Note that the maximum offset that you can set is 2^29 -1 (536870911), as Redis
Strings are limited to 512 megabytes. If you need to grow beyond this size, you
can use 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` commands, you can use Redis
strings as a linear array with O(1) random access. This is a very fast and
efficient storage in many real world use cases.
@return
@integer-reply: the length of the string after it was modified by the command.
@examples
Basic usage:
```cli
SET key1 "Hello World"
SETRANGE key1 6 "Redis"
GET key1
```
Example of zero padding:
```cli
SETRANGE key2 6 "Redis"
GET key2
```
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