Google Cloud Storage

The Google Cloud Storage connector lets Tabsdata read files from and write files to Google Cloud Storage.

The GCSSrc connector can be used by a publisher function to read data from Google Cloud Storage into a Tabsdata table.

The GCSDest connector can be used by a subscriber function to write data from a Tabsdata table into Google Cloud Storage.

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 GCSSrc connector can be used by a publisher function to read data from Google Cloud Storage into a Tabsdata table. See the full publisher walkthrough

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

Prerequisites

• The bucket exists and is reachable from the Tabsdata server.
• The service account can list the bucket and read every object matched by paths.
• The object format and compression match format and format_cfg.

Publisher

Configure GCSSrc as the source of a publisher function to select the files that Tabsdata reads from Google Cloud Storage.

publish_orders.py

from tabsdatak.api import publisher
from tabsdatak.conn.gcs import GCSSrc, SrcFileFormat

@publisher(
    source=GCSSrc(
        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 Google Cloud Storage.

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

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

For example:

GCSSrc(
    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 Google Cloud Storage include a @td.file.path metadata column containing the source file's URI.

Subscriber

The GCSDest connector can be used by a subscriber function to write data from a Tabsdata table into Google Cloud Storage. See the full subscriber walkthrough

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

Prerequisites

• The bucket exists and is reachable from the Tabsdata server.
• The service account can create and write objects under the configured base_path.
• The destination path is relative and does not contain a glob.

Subscriber

Configure GCSDest as the destination of a subscriber function to define where Tabsdata writes files in Google Cloud Storage.

write_orders.py

from tabsdatak.api import subscriber
from tabsdatak.conn.gcs import GCSDest, DestFileFormat

@subscriber(
    destination=GCSDest(
        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 in Google Cloud Storage.

Each path is relative to the base_path configured in GCSDestConn. 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:

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

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

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 object; 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 objects 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 object. 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 Google Cloud Storage 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

Google Cloud Storage publishers use GCSSrcConn to define the bucket and credentials used by the publisher.

conn-gcs-in.yaml

kind: connectionDef
apiVersion: '1.0'
type: tabsdatak.conn.gcs:GCSSrcConn
spec:
  bucket: 'acme-ingest'
  credentials:
    kind: gcpJsonCredentials
    apiVersion: '1.0'
    type: tabsdatak.conn.common.types:GCPJson
    spec:
      json: 'secret:{"type":"service_account",...}'

• required
• required
• optional
• optional
• 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 gcs-file-in --file conn-gcs-in.yaml

Edit the template file with the Google Cloud Storage connection information, check it, and create the collection with it:

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

tdk collection create --name gcs_in --conn-file conn-gcs-in.yaml

Then register the publisher in the collection:

tdk fn register --coll gcs_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: GCSSrc for a collection created with GCSSrcConn. Transformers go in a collection of their own.
• To change the connection later, for example to rotate a password, run tdk collection update --name gcs_in --conn-file conn-gcs-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

bucket

The name of the GCS bucket that contains the files to publish.

credentials

The service-account JSON credential used to access the bucket. GCPJson requires a json key holding the full service-account key document.

project

Optional GCP project id associated with the bucket.

base_path

Sets the base path within the bucket. All paths configured in GCSSrc are relative to this path.

base_path starts with /, cannot end with /, and cannot contain empty path segments. The default is /.

conn_cfg

Optional connector configuration overrides.

Subscriber connection

Google Cloud Storage subscribers use GCSDestConn to define the bucket and credentials used by the subscriber.

conn-gcs-out.yaml

kind: connectionDef
apiVersion: '1.0'
type: tabsdatak.conn.gcs:GCSDestConn
spec:
  bucket: 'acme-exports'
  credentials:
    kind: gcpJsonCredentials
    apiVersion: '1.0'
    type: tabsdatak.conn.common.types:GCPJson
    spec:
      json: 'secret:{"type":"service_account",...}'

• required
• required
• optional
• optional
• 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 gcs-file-out --file conn-gcs-out.yaml

Edit the template file with the Google Cloud Storage connection information, check it, and create the collection with it:

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

tdk collection create --name gcs_out --conn-file conn-gcs-out.yaml

Then register the subscriber in the collection:

tdk fn register --coll gcs_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: GCSDest for a collection created with GCSDestConn. Transformers go in a collection of their own.
• To change the connection later, for example to rotate a password, run tdk collection update --name gcs_out --conn-file conn-gcs-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

bucket

The name of the GCS bucket where the subscriber writes files.

credentials

The service-account JSON credential used to access the bucket. GCPJson requires a json key holding the full service-account key document.

project

Optional GCP project id associated with the bucket.

base_path

Sets the base path within the bucket. All paths configured in GCSDest are relative to this path.

base_path starts with /, cannot end with /, and cannot contain empty path segments. The default is /.

conn_cfg

Optional connector configuration overrides.