chore(test): run REST fixture's SQLite backend in WAL mode

[kevinjqliu]

Part of apache/iceberg#18043

The REST fixture compose sets CATALOG_URI=jdbc:sqlite:file:/tmp/iceberg_rest_mode=memory, carried over from the old databricks image. That isn't an in-memory db, there's no ? so iceberg_rest_mode=memory is just part of the filename. It's a file-backed SQLite db on the default rollback journal, which only lets one connection touch the db at a time, so parallel clients can fail with SQLITE_BUSY ("database is locked").

This switches it to jdbc:sqlite:/tmp/iceberg_catalog.db?journal_mode=WAL, matching the new fixture default in apache/iceberg#18044.

🤖 Generated with Claude Code

[Copilot]

🟢 Approval recommended

The change is a small, targeted docker-compose configuration update that aligns with the stated goal of reducing SQLite lock contention.

Pull request overview

Updates the Iceberg REST test fixture’s docker-compose configuration to use a file-backed SQLite catalog database in WAL mode to reduce SQLITE_BUSY lock contention when tests run parallel clients.

Changes:

• Fixes the SQLite JDBC URL to point to an explicit file path instead of an accidentally file-backed “mode=memory” filename.
• Enables SQLite WAL journaling via journal_mode=WAL in the JDBC URL to improve concurrent access behavior.

File summaries

File	Description
src/iceberg/test/resources/iceberg-rest-fixture/docker-compose.yml	Switch SQLite JDBC URL to a real file-backed DB and enable WAL mode for better parallel test reliability.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 0
• Review effort level: Lite

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