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Redis -- why is the string length of string emstr the upper limit of 44 bytes?

2022-04-23 07:59:00 【Dream river dream】

redis Structure of objects
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Such a structure occupies 16 byte

string The structure of the object
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1）string Code the first –64 Bit signed integer

2）string Code the second –embstr

3）string Code the third –raw

This structure requires memory allocation twice , Primary distribution 16 Bytes of redis Object structure , Primary distribution sds object ,sds It's dynamic expansion , Strategy is ： The length of the string is less than 1M Before , The expansion space is doubled , That is to keep 100% Redundant null
between . When the length exceeds 1M after , In order to avoid the waste of redundant space after doubling , Each expansion only allocates more 1M The size of the redundant space .