Local File System

The Local File System connector lets Tabsdata read files from and write files to the server's own filesystem.

The LocalFileSrc connector can be used by a publisher function to read data from local files into a Tabsdata table.

The LocalFileDest connector can be used by a subscriber function to write data from a Tabsdata table into local files.

Supported formats

Format	Publish	Subscribe
AUTO	Yes	Yes
CSV	Yes	Yes
JSON	Yes	Yes
AVRO	Yes	Yes
PARQUET	Yes	Yes
LOG	Yes	No

Publisher

The LocalFileSrc connector can be used by a publisher function to read data from local files into a Tabsdata table. See the full publisher walkthrough

The publisher is registered in a collection created with a LocalFileSrcConn connection. The connection, and how to create the collection, are described in Publisher connection, at the end of this page.

Prerequisites

• The configured base_path exists on the Tabsdata server and is readable by the function worker.
• Every source path stays under base_path; parent-directory segments are refused.
• The file format and compression match format and format_cfg.

Publisher

Configure LocalFileSrc as the source of a publisher function to select the files that Tabsdata reads from disk.

publish_orders.py

from tabsdatak.api import publisher
from tabsdatak.conn.localfile import LocalFileSrc, SrcFileFormat

@publisher(
    source=LocalFileSrc(
        paths=[
            "incoming/orders.parquet",
        ],
    ),
    output_tables=["orders"],
)
def publish_orders(orders):
    return orders

• required
• optional
• optional
• optional
• optional

Function Config Parameters

paths

Defines the files that the publisher reads from disk.

Each path is relative to the base_path configured in LocalFileSrcConn. Source paths:

• cannot begin or end with /
• cannot contain empty path segments
• can contain a * glob in the final path segment

For example:

LocalFileSrc(
    paths=[
        "orders/2026/*.parquet",
        "customers/customers.csv",
    ]
)

Each element in paths represents one source slot and maps positionally to an argument in the publisher function.

When a path uses a glob to match multiple files, the matching files are provided through the corresponding publisher input.

format

Sets the format used to read the source files.

Supported formats are AUTO, CSV, JSON, AVRO, PARQUET, and LOG. The default is AUTO, which determines the format from the file extension.

format_cfg

Sets format-specific reader options. Configuration is keyed by SrcFileFormat.

initial_last_modified

Sets the initial cutoff for incremental ingestion.

On the first run, Tabsdata imports files modified at or after the specified timestamp. The cutoff then advances so subsequent runs only import newer files.

src_cfg

Sets additional source configuration.

The following options are supported:

Option	Description
tabsdata.file.chunk_size	Controls the size of chunks used when reading files.
tabsdata.src_metadata.drop	When True, excludes the @td.file.path metadata column.

By default, rows read from disk include a @td.file.path metadata column containing the source file's path.

Subscriber

The LocalFileDest connector can be used by a subscriber function to write data from a Tabsdata table into local files. See the full subscriber walkthrough

The subscriber is registered in a collection created with a LocalFileDestConn connection. The connection, and how to create the collection, are described in Subscriber connection, at the end of this page.

Prerequisites

• The configured base_path exists on the Tabsdata server and is writable by the function worker.
• Every destination path stays under base_path; parent-directory segments and globs are refused.
• Enough disk space is available for the files written by the run.

Subscriber

Configure LocalFileDest as the destination of a subscriber function to define where Tabsdata writes files on disk.

write_orders.py

from tabsdatak.api import subscriber
from tabsdatak.conn.localfile import LocalFileDest, DestFileFormat

@subscriber(
    destination=LocalFileDest(
        paths=[
            "exports/orders.parquet",
        ],
    ),
    input_tables=["orders"],
)
def write_orders(orders):
    return orders

• required
• optional
• optional
• optional

Function Config Parameters

paths

Defines where the subscriber writes files on disk.

Each path is relative to the base_path configured in LocalFileDestConn. Destination paths:

• cannot begin or end with /
• cannot contain empty path segments
• cannot contain globs

Each element in paths represents one destination slot and maps positionally to a value returned by the subscriber function.

Destination paths can contain variables that Tabsdata substitutes when the subscriber runs:

Variable	Value
${EXEC_PLAN_ID}	Current execution plan ID.
${TRX_ID}	Current transaction ID.
${EXEC_PLAN_TS}	Timestamp when the execution plan started.

For example:

LocalFileDest(
    paths=[
        "exports/${EXEC_PLAN_ID}/orders.parquet",
    ]
)

Dynamic paths can be used to create a new file for each execution instead of overwriting an existing one.

format

Sets the format used to write the destination file.

Supported formats are AUTO, CSV, JSON, AVRO, and PARQUET. The default is AUTO, which determines the format from the destination file extension.

format_cfg

Sets format-specific writer options. Configuration is keyed by DestFileFormat.

dest_cfg

Sets additional destination configuration.

The tabsdata.file.chunk_size option controls the size of chunks used when writing files.

File behavior

Each entry in a publisher's paths is one source slot. A literal path reads one file; a final-segment * glob can read several. The slots map by position to the publisher function arguments and then to output_tables.

initial_last_modified sets the cutoff for the first run. After a successful run, Tabsdata advances the cutoff so the same unchanged files are not published again.

Each entry in a subscriber's paths is one destination slot and maps by position to a returned value. Use ${EXEC_PLAN_ID}, ${TRX_ID}, or ${EXEC_PLAN_TS} in a path when every run needs a new file. A fixed path writes to the same location again.

Operational notes

• Without trigger_by, a publisher runs only when triggered manually, while a subscriber runs when any input table commits. Set trigger_by to change when the function runs.
• Tabsdata validates the connection document when the collection is created, but it does not contact local filesystem then. A bad path, credential, or permission fails when the function runs.
• Globs are allowed only for publisher source paths, and only in the final path segment. Subscriber destination paths cannot contain globs.
• All configured paths are relative to the connection's base_path.

Publisher connection

Local File System publishers use LocalFileSrcConn to define the root filesystem path used by the publisher. Unlike the cloud storage connectors, there is no bucket and no credentials: the connector reads directly off the server's own disk.

conn-local-in.yaml

kind: connectionDef
apiVersion: '1.0'
type: tabsdatak.conn.localfile:LocalFileSrcConn
spec:
  base_path: '/data/hr'

• required
• optional

Create the collection

A publisher is registered in a source collection, and a source collection is created with its connection. Every function registered in the collection uses that connection.

Generate a connection template, which lists all the connection fields:

tdk connection template --type local-file-in --file conn-local-in.yaml

Edit the template file with the Local File System connection information, check it, and create the collection with it:

tdk connection validate --file conn-local-in.yaml

tdk collection create --name local_in --conn-file conn-local-in.yaml

Then register the publisher in the collection:

tdk fn register --coll local_in --path publish_orders.py::publish_orders

• The collection goes in the sources group, because the connection is a source connection. --group can be left out; if it is given, it must be sources.
• secret:<value> gives a secret value in the file itself. $secret:<ENV_VAR> reads it from an environment variable when the collection is created, so the value never appears in the file. Either way, Tabsdata stores the secret separately, and the stored connection only shows a placeholder.
• Functions in the collection must use the connector of its connection: LocalFileSrc for a collection created with LocalFileSrcConn. Transformers go in a collection of their own.
• To change the connection later, for example to rotate a password, run tdk collection update --name local_in --conn-file conn-local-in.yaml. The connector cannot change; to use another one, create another collection.
• Creating a source or destination collection requires permission to manage the project.

Connection Config Parameters

base_path

The absolute filesystem path that acts as the root for all paths the publisher reads. Unlike the cloud storage connectors, base_path is required here: there is no bucket to fall back on, so the server needs a starting point on disk.

conn_cfg

Optional connector configuration overrides.

Subscriber connection

Local File System subscribers use LocalFileDestConn to define the root filesystem path used by the subscriber. Unlike the cloud storage connectors, there is no bucket and no credentials: the connector writes directly onto the server's own disk.

conn-local-out.yaml

kind: connectionDef
apiVersion: '1.0'
type: tabsdatak.conn.localfile:LocalFileDestConn
spec:
  base_path: '/data/exports'

• required
• optional

Create the collection

A subscriber is registered in a destination collection, and a destination collection is created with its connection. Every function registered in the collection uses that connection.

Generate a connection template, which lists all the connection fields:

tdk connection template --type local-file-out --file conn-local-out.yaml

Edit the template file with the Local File System connection information, check it, and create the collection with it:

tdk connection validate --file conn-local-out.yaml

tdk collection create --name local_out --conn-file conn-local-out.yaml

Then register the subscriber in the collection:

tdk fn register --coll local_out --path write_orders.py::write_orders

• The collection goes in the destinations group, because the connection is a destination connection. --group can be left out; if it is given, it must be destinations.
• secret:<value> gives a secret value in the file itself. $secret:<ENV_VAR> reads it from an environment variable when the collection is created, so the value never appears in the file. Either way, Tabsdata stores the secret separately, and the stored connection only shows a placeholder.
• Functions in the collection must use the connector of its connection: LocalFileDest for a collection created with LocalFileDestConn. Transformers go in a collection of their own.
• To change the connection later, for example to rotate a password, run tdk collection update --name local_out --conn-file conn-local-out.yaml. The connector cannot change; to use another one, create another collection.
• Creating a source or destination collection requires permission to manage the project.

Connection Config Parameters

base_path

The absolute filesystem path that acts as the root for all paths the subscriber writes. Unlike the cloud storage connectors, base_path is required here: there is no bucket to fall back on, so the server needs a starting point on disk.

conn_cfg

Optional connector configuration overrides.