Это структура записи:
<prevlen> <encoding> <entry-data>
Мой вопрос заключается в том, почему преблен потребляет "пять" байтов, отличных от "шести" или "четырех" байтов
Комментарий ziplist в исходном коде Redis ниже:
* Every entry in the ziplist is prefixed by metadata that contains two pieces
* of information. First, the length of the previous entry is stored to be
* able to traverse the list from back to front. Second, the entry encoding is
* provided. It represents the entry type, integer or string, and in the case
* of strings it also represents the length of the string payload.
* So a complete entry is stored like this:
*
* <prevlen> <encoding> <entry-data>
*
* Sometimes the encoding represents the entry itself, like for small integers
* as we'll see later. In such a case the <entry-data> part is missing, and we
* could have just:
*
* <prevlen> <encoding>
*
* The length of the previous entry, <prevlen>, is encoded in the following way:
* If this length is smaller than 254 bytes, it will only consume a single
* byte representing the length as an unsinged 8 bit integer. When the length
* is greater than or equal to 254, it will consume 5 bytes. The first byte is
* set to 254 (FE) to indicate a larger value is following. The remaining 4
* bytes take the length of the previous entry as value.