R Internals: Data Sizes With Nullable Columns

When looking at the data sent, the size of the packages and “drilling” into the TCP packets we could deduct that: :

Each column has an over-head of 32 bytes (at least for non nullable data)
The size of the column in one row is the size of the data type for numeric types.
For decimal and numeric an extra byte is added to each column, where this byte indicates the precision.
Columns of alpha numeric type all had 2 bytes pre-pended to the bytes, except max types.
For char and nchar the storage size was 2 bytes plus the size the column was defined as.
For varchar and nvarchar the storage size was 2 bytes plus the size of the data stored.
For the varmax data types the number of bytes that were pre-pended varied dependent on the data size.

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