[BEAM-2406] NullPointerException when writing an empty table to BigQuery

• Type: Bug
• Status: Resolved
• Priority: P3
• Resolution: Fixed
• Affects Version/s: 2.0.0
• Fix Version/s: 2.1.0
• Component/s: io-java-gcp
• Assignee: Reuven Lax
• Reporter: Ben Chambers
• Created: 03/Jun/17 00:25
• Updated: 24/Jul/20 20:18
• Resolved: 15/Jul/17 17:05

Description

Originally reported on Stackoverflow:
https://stackoverflow.com/questions/44314030/handling-empty-pcollections-with-bigquery-in-apache-beam

It looks like if there is no data to write, then WritePartitions will return a null destination, as explicitly stated in the comments:

https://github.com/apache/beam/blob/v2.0.0/sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/bigquery/WritePartition.java#L126

But, the ConstantTableDestination doesn't turn that into the constant destination as the comment promises, instead it returns that `null` destination:

https://github.com/apache/beam/blob/53c9bf4cd325035fabde192c63652ef6d591b93c/sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/bigquery/DynamicDestinationsHelpers.java#L74

This leads to a null pointer error here since the `tableDestination` is that null result from calling `getTable`:

https://github.com/apache/beam/blob/v2.0.0/sdks/java/io/google-cloud-platform/src/main/java/org/apache/beam/sdk/io/gcp/bigquery/WriteTables.java#L97

Issue Links

• links to: GitHub Pull Request #3293