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Data Warehouse Type Bit Data Bit

I am studying the mysql testing guide. in the Data type bit section:

a BIT (4) sores 4 bits per value

and that the storage requirement for column BIT (n) is (n + 7) / 8. I do not understand this part. shldnt BIT (4) takes up only 4 bits of memory?

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2 answers

This is actually a clumsy way to round the result. This means that BIT (1) - BIT (8) takes 1 byte, BIT (9) - BIT (16) takes 2 bytes, etc. There is no overhead for 7 bits. Divide the number of bits by 8 and round the result. BIT (4) will accept 1 byte.

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It seems that the overhead of 7 bits is likely to identify the memory block as BIT storage.

7 , BIT (n), 8, . (n + 7)/8 BYTES

, 4 2 . "", , .

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Source: https://habr.com/ru/post/1715808/

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