[BEAM-12628] AvroCoder changed underlying String class for SpecificRecords

• Type: Bug
• Status: Triage Needed
• Priority: P1
• Resolution: Fixed
• Affects Version/s: 2.30.0
• Fix Version/s: 2.33.0
• Component/s: io-java-avro
• Assignee: Claire McGinty
• Reporter: Ryan Skraba
• Created: 16/Jul/21 14:04
• Updated: 13/Apr/23 11:06
• Resolved: 06/Oct/21 21:59

Description

The AvroCoder changes for BEAM-2303 changes the reader/writer from the Avro ReflectDatum* classes to the SpecificDatum* classes.

Because of the way Avro handles Strings, however, the underlying instances for String data are deserialised as org.apache.avro.util.Utf8 instances instead of java.lang.String.

This causes:
1. an unexpected behaviour change when migrating to Beam 2.30.0
2. potential serialization issues when using these String instances (Utf8 instances don't implement Serializable)
3. an inconsistent API between AvroCoder and AvroSink/AvroSource (the latter still use ReflectDatum*)

(Original report on the mailing list and PR)

Issue Links

• relates to: AVRO-3208 [Java] Utf8 strings should be Serializable
• links to: GitHub Pull Request #15292
• links to: GitHub Pull Request #15295
• links to: GitHub Pull Request #15616
• links to: GitHub Pull Request #15622