One
| Input | Output | Alias |
|---|---|---|
| ✔ | ✗ |
Description
The One format is a special input format that doesn't read any data from file, and returns only one row with column of type UInt8, name dummy and value 0 (like the system.one table).
Can be used with virtual columns _file/_path to list all files without reading actual data.
Example Usage
Example:
Query
SELECT _file FROM file('path/to/files/data*', One);
Response
┌─_file────┐
│ data.csv │
└──────────┘
┌─_file── ────┐
│ data.jsonl │
└────────────┘
┌─_file────┐
│ data.tsv │
└──────────┘
┌─_file────────┐
│ data.parquet │
└──────────────┘