# parquet_metadata

## Description

One input row describing a Parquet file footer, including file, column and row-group metadata. With file(), the format supplies its fixed metadata schema without a third argument.

Input only. Select it with `FORMAT parquet_metadata`. Names ignore ASCII case; use the snake_case name shown here.

The input is a complete Parquet file, but the output relation describes its footer rather than its data rows. It includes file-level counts and nested column and row-group records.

file() can supply the fixed schema automatically. With an explicit target, only known metadata fields are accepted and ordinary target conversions apply. This format has no result encoder.

```text
INSERT INTO table [(columns)] [SETTINGS ...] FORMAT parquet_metadata
<data>
```

## Example usage

```sql
SELECT name,is_input,is_output FROM system.formats WHERE name='parquet_metadata' FORMAT csv;
```

```text
"parquet_metadata",1,0
```

## Format settings

Use a statement `SETTINGS` clause; these options are not persisted by `SET`.

| Setting       | Type     | Default | Meaning                                                                                  |
| ------------- | -------- | ------- | ---------------------------------------------------------------------------------------- |
| `snappy_mode` | `String` | `basic` | Read Snappy client files as basic (Hadoop blocks) or framed (standard streaming format). |

## Inspect a file

Run these commands from the server configuration directory with the default user_files_path. They create a one-column, one-row Parquet file under the server file root and inspect its footer.

```sh
mkdir -p user_files
./coordinator client --database data --query "SELECT CAST(7 AS Int64) AS id FORMAT parquet" > user_files/sample.parquet
./coordinator client --database data --query "SELECT num_rows,num_columns,num_row_groups FROM file('sample.parquet',parquet_metadata) FORMAT csv"
```

```text
1,1,1
```