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When I read the redis embstr to store some short string content, show these advantage:

Embeded String: If the size of the value string is less than or equal to 44 bytes, Redis saves the string in the same chunk of the Redis object itself. This is more memory efficient than the Raw String encoding. Also, it's more cache-friendly.

that told that the embstr is more efficiency than raw string. why the embstr more efficiency?

Dolphin
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1 Answers1

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With embedded string encoding, the string is allocated with Redis object. So it only does a single malloc call.

 ------------------------------------------------------
|Redis object header | data pointer =|> embedded string|
 ------------------------------------------------------

With raw string encoding, the string is allocated separately. So it needs to do 2 malloc calls.

 -----------------------------------
|Redis object header | data pointer |
 -----------------------------------
                             ||
                             \/
                        ------------
                       | raw string |
                        ------------

Since embedded string is near Redis object header, it's also more cache friendly.

for_stack
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