Does auto compaction break z-ordering?

Does auto compaction break existing z-ordered tables in delta lake?

Good question. I am doing the Certification study for Databricks as it so happens.

They seem at odds. Short answer to your question is YES.

Why?

ZORDER as in %sql OPTIMIZE delta./mnt/delta/t1 ZORDER BY (c1, c2) is essentially clustering to speed up filter, where operations.

Auto Compaction, when enabled, is about making fewer, larger files from smaller files to improve performance - small files problems. That will be done without being cognisant of ZORDER. Thus breaking the ZORDER aspects achieved. NB: I read also that it is most applicable for Structured Streaming.