Tableau Reader (Labs)

Reads a table from a Tableau Hyper file.

Note about file system port usage:
Hyper files on a remote file system must be fully downloaded before they can be read. Hence the dialog provides a Download button to trigger a download, and the dialog fields will only update after the download is complete.

Note about usage on KNIME Hub:
Executing this node on a KNIME Hub is disabled by default due to this bug in the Tableau Hyper library. The node can be enabled by an administrator by setting the vmArguments property -Dknime.tableau.reader.hub.enabled=true of the used Hub Execution Context (similarly to the process described here). Enabling this property is discouraged and may cause the Hub Executor to crash when reading big Tableau Hyper files, as KNIME cannot limit the amount of memory Tableau uses.

Options

Source
Select a file location which stores the data you want to read. When clicking on the browse button, there are two default file system options to choose from:
  • The current Hub space: Allows to select a file relative to the Hub space on which the workflow is run.
  • URL: Allows to specify a URL (e.g. file://, http:// or knime:// protocol).
Download
Download a remote Tableau file when using a file system port. Once the file is downloaded, it can be downloaded again in case the remote file has changed. The dialog fields will update once the download is complete.
Schema
The name of the schema which contains the table.
Table
The name of the table to read.
Skip first data rows
Use this option to skip the specified number of valid data rows. This has no effect on which row will be chosen as a column header. Skipping rows prevents parallel reading of individual files.
Limit number of rows
If enabled, only the specified number of data rows are read. The column header row (if selected) is not taken into account. Limiting rows prevents parallel reading of individual files.
Maximum number of rows
Defines the maximum number of rows that are read.
If schema changes
Specifies the node behavior if the content of the configured file/folder changes between executions, i.e., columns are added/removed to/from the file(s) or their types change. The following options are available:
  • Fail: If set, the node fails if the column names in the file have changed. Changes in column types will not be detected.
  • Use new schema: If set, the node will compute a new table specification for the current schema of the file at the time when the node is executed. Note that the node will not output a table specification before execution and that it will not apply transformations, therefore the transformation tab is disabled.
  • Ignore (deprecated): If set, the node tries to ignore the changes and outputs a table with the old table specification. This option is deprecated and should never be selected for new workflows, as it may lead to invalid data in the resulting table. Use one of the other options instead.
Enforce types
Controls how columns whose type changes are dealt with. If selected, the mapping to the KNIME type you configured is attempted. The node will fail if that is not possible. If unselected, the KNIME type corresponding to the new type is used.
Transformations
Use this option to modify the structure of the table. You can deselect each column to filter it out of the output table, use the arrows to reorder the columns, or change the column name or column type of each column. Note that the positions of columns are reset in the dialog if a new file or folder is selected. Whether and where to add unknown columns during execution is specified via the special row <any unknown new column>. It is also possible to select the type new columns should be converted to. Note that the node will fail if this conversion is not possible e.g. if the selected type is Integer but the new column is of type Double.

Input Ports

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File system

Output Ports

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Read table

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