apache/iceberg

Docs: Clarify Spark branch write precedence over WAP branch

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#15,916 opened on Apr 9, 2026

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Description

Feature Request / Improvement

After https://github.com/apache/iceberg/pull/15288, Spark Writing to Branches doc (docs/docs/spark-writes.md) no longer matches that in codes.

   * <p>The target branch can be specified via table identifier, write option, or in SQL:
   *
   * <ul>
   *   <li>The identifier and option branches can't conflict. If both are set, they must match.
   *   <li>Identifier and option branches take priority over the session WAP branch.
   *   <li>If neither the option nor the identifier branch is set and WAP is enabled for this table,
   *       use the WAP branch from the session SQL config.
   * </ul>
   *
   * <p>Note: WAP ID and WAP branch cannot be set at the same time.
   *
   * <p>Note: The target branch may be created during the write operation if it does not exist.

Query engine

Spark

Willingness to contribute

  • I can contribute this improvement/feature independently
  • I would be willing to contribute this improvement/feature with guidance from the Iceberg community
  • I cannot contribute this improvement/feature at this time

Contributor guide

Research direction
Review the Spark writing to branches documentation and the code changes in PR #15288 to align the documentation with the actual behavior regarding branch write precedence.
Tech stack
java
Domain
documentationdata
Issue type
Documentation
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Apache Iceberg basicsSpark writing to branches
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75