JSONColumns
Description
Tip
The output of the JSONColumns* formats provides the ClickHouse field name and then the content of each row of the table for that field; visually, the data is rotated 90 degrees to the left.
In this format, all data is represented as a single JSON Object. Note that JSONColumns output format buffers all data in memory to output it as a single block and it can lead to high memory consumption.
Example Usage
Example:
{
"num": [42, 43, 44],
"str": ["hello", "hello", "hello"],
"arr": [[0,1], [0,1,2], [0,1,2,3]]
}
During import, columns with unknown names will be skipped if setting input_format_skip_unknown_fields is set to 1. Columns that are not present in the block will be filled with default values (you can use the input_format_defaults_for_omitted_fields setting here)