File

The file:// source reads local files in various file formats through the same readers used by the local and remote filesystem sources.

URI format

Everything after file:// is treated as a filesystem path. Relative paths resolve against the current working directory; an extra leading slash gives an absolute path.

file://<path>

Form	Example	Resolves to
Relative path	file://data/users.csv	<cwd>/data/users.csv
Absolute path (POSIX)	file:///srv/data/users.jsonl	/srv/data/users.jsonl
Windows drive	file:///C:/data/users.csv (or file://C:/data/users.csv)	C:\data\users.csv
Windows UNC	file:////server/share/users.csv	\\server\share\users.csv
Path via --source-table	--source-uri file:// --source-table data/users.parquet	<cwd>/data/users.parquet
Glob	file://data/*.csv	all matching files in <cwd>/data
Format hint	file://feed.dat#csv	feed.dat read as CSV

Tip

file:// intentionally treats the first path segment as part of the path, not as an RFC-8089 host. This is what makes the two-slash form file://data/x.csv (relative to the working directory) work, matching how csv:// already behaves. Use the three-slash form file:///abs/x.csv for absolute paths.

Note

Windows paths are supported: file:///C:/data/x.csv (or file://C:/data/x.csv) reads the drive path C:\data\x.csv, and file:////server/share/x.csv reads the UNC path \\server\share\x.csv. Backslash input (file://\\server\share\x.csv) is accepted as well.

Glob patterns

The path may contain a glob pattern to load multiple files at once. The split into directory and pattern happens at the first segment containing a glob character (*, ?, [), so recursive patterns work:

Pattern	Description
file://data/*.csv	All CSV files at the top level of <cwd>/data.
file://data/**/*.jsonl	All JSONL files under <cwd>/data, recursively.
file:///srv/logs/**/*.csv.gz	All gzipped CSV files under /srv/logs, recursively.

Compressed files

Gzipped files (.gz) are detected and decompressed automatically, so file://data/events.csv.gz loads without any extra configuration.

Destination connector

When addressing filesystems for writing, the output format is taken from the destination file extension (.csv, .jsonl, .parquet) or from an explicit format hint (#format), exactly like the source side is doing it. The written file drops dlt’s internal bookkeeping columns, so it round-trips cleanly.

omniload ingest \
    --source-uri 'postgres://user:password@host:5432/db' \
    --source-table 'public.users' \
    --dest-uri 'file://export/users.parquet' \
    --dest-table 'public.users'

Destination URI	Output
file://out.csv	CSV written to <cwd>/out.csv
file:///srv/out.jsonl	JSONL written to /srv/out.jsonl
file://export/users.parquet	Parquet written to <cwd>/export/users.parquet
file://feed.dat#csv	CSV written to <cwd>/feed.dat

The path grammar is identical to the source (relative-to-cwd, absolute, Windows drive and UNC forms all resolve the same way). Supported output formats are csv, jsonl and parquet; any other extension (or none) is rejected with the supported-format list. --dest-table must be <dataset>.<table>; it only names the intermediate layout, the output file is the URI path.

Parent directories in the destination path are created if they don’t exist, and an existing file at the destination is overwritten. Globs are a read-only feature and are not supported when writing.

Relationship to csv://

The csv:// scheme still exists and is unchanged: it reads and writes a single local CSV file. file:// is the broader local path, covering JSONL and Parquet as well as CSV, plus (on read) globbing and gzip decompression. Prefer file:// for local files; use csv:// only when you specifically want the standalone CSV reader.

Examples

Load CSV into DuckDB

omniload ingest \
    --source-uri 'file://data/users.csv' \
    --source-table 'users' \
    --dest-uri 'duckdb:///local.duckdb' \
    --dest-table 'public.users'

The --source-table value is only used as the path when the URI path is empty (the split form above); otherwise it is ignored, and the destination table is controlled by --dest-table.

Load spreadsheet into DuckDB

omniload ingest \
    --source-uri 'file://users.xlsx#sheet_name=staff' \
    --dest-uri 'duckdb:///local.duckdb' \
    --dest-table 'public.staff'

Here, sheet_name is a reader hint to address the worksheet within the workbook by name. If the parameter is omitted, the reader will read the first sheet of the workbook. The loader is using polars.read_excel, please consult its documentation about all available parameters and their descriptions.