Blocking transform Icon Blocking transform


The Blocking transform blocks all output until the very last row is received from the previous transform.

the transform blocks until it gets the last row. It does not block until the previous transform is finished 100% which is functionality found in the other transform Blocking until transforms finish.

At that point, the last row is sent to the next transform or the complete input is sent off to the next transform. Use the Blocking transform for triggering plugins, stored procedures, Java scripts, …​ or for synchronization purposes.

Supported Engines

Hop Engine



Maybe Supported


Maybe Supported


Maybe Supported


Option Description

Transform name

Name of the transform; this name has to be unique in a single pipeline.

Pass all rows?

Determines whether to pass one row or all rows

Spool directory

The directory in which the temporary files are stored if needed; the default is the standard temporary directory for the system

Spool-file prefix

Choose a recognizable prefix to identify the files when they appear in the temp directory

Cache size

The more rows you can store in memory, the faster the transform works

Compress spool files?

Compresses temporary files when they are needed