Row data
Following the file header is a sequence of records that contain the data for each row of data. Each record starts with a header:
| Length (bytes) | Description | Comments |
|---|---|---|
| 4 | Row length |
A 32-bit integer in little-endian format containing the length of the row's data in bytes. It includes the size of data only, not the header. Note: The number of bytes in each row can vary not only because of variable-length data, but also because columns containing NULL values do not have any data in the row. If column 3 has a NULL value, then column 4's data immediately follows the end of column 2's data. See the next |
Number of columns ¸ 8 rounded up (CEILING(NumFields / ( sizeof(uint8) * 8) ); ) |
Null value bit field | A series of bytes whose bits indicate whether a column contains a NULL. The most significant bit of the first byte indicates whether the first column in this row contains a NULL, the next most significant bit indicates whether the next column contains a NULL, and so on. If a bit is 1 (true) then the column contains a NULL, and there is no value for the column in the data for the row. |
Following the record header is the column values for the row. There is no separator characters for these values. Their location in the row of data is calculated based on where the previous column's data ended. Most data types have a fixed width, so their location is easy to determine. Variable-width values (such as VARCHAR and VARBINARY) start with a count of the number of bytes the value contains.
See the table in the previous section for details on how each data type's value is stored in the row's data.