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Diffstat (limited to 'iredis/data/commands/setrange.md')
| -rw-r--r-- | iredis/data/commands/setrange.md | 31 |
1 files changed, 16 insertions, 15 deletions
diff --git a/iredis/data/commands/setrange.md b/iredis/data/commands/setrange.md index 078fb34..617e3d5 100644 --- a/iredis/data/commands/setrange.md +++ b/iredis/data/commands/setrange.md @@ -1,29 +1,30 @@ 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_. +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. +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. +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. +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 |