apache/iceberg

Core: Stream DV Puffin rewrite in RewriteTablePathUtil to reduce memory pressure

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#15924 opened on Apr 9, 2026

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 (1 comment) (0 reactions) (1 assignee)Java (5,146 stars) (1,915 forks)batch import
coregood first issueimprovement

Description

Feature Request / Improvement

Description

RewriteTablePathUtil.rewriteDVFile currently rewrites deletion vector (DV) Puffin files by reading all rewritten blobs into an in-memory list before writing them out, which can create unnecessary memory pressure when rewriting larger DV files or files with many blobs.

Suggested improvement

Refactor RewriteTablePathUtil.rewriteDVFile to stream rewritten blobs directly to the output PuffinWriter while iterating through the source blobs, instead of collecting all rewritten blobs into a temporary list first.

Query engine

None

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

Tech stack
java
Domain
performancedatabase
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
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.
blocked
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
JavaApache Iceberg basicsStreaming concepts
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
The issue is to refactor RewriteTablePathUtil.rewriteDVFile to stream blobs instead of collecting them in memory. Examine the existing implementation in the Apache Iceberg repository. Since it is assigned, coordinate with the assignee before starting work. No PRs or additional comments are available yet.