fix: replay unflushed WAL entries into memtable on restart#6532
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hamersaw wants to merge 2 commits intolance-format:mainfrom
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fix: replay unflushed WAL entries into memtable on restart#6532hamersaw wants to merge 2 commits intolance-format:mainfrom
hamersaw wants to merge 2 commits intolance-format:mainfrom
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On crash/restart, WAL entries that were written but not yet flushed to a generation were silently lost. The memtable started empty, dropping any data durably written to the WAL. This adds replay logic in ShardWriter::open() that scans WAL entries from replay_after_wal_entry_position + 1 forward, inserting them back into the memtable before accepting new writes. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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# Conflicts: # rust/lance/src/dataset/mem_wal/wal.rs
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I think this one is fixed in #6675 now |
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Summary
WalFlusher::replay_wal_entries()that scans fromreplay_after_wal_entry_position + 1forward, re-inserting non-empty WAL entries into the memtableShardWriter::open()before accepting new writes, withnext_wal_entry_positionadvanced past replayed entriesTest plan
test_replay_wal_entries— writes 3 WAL entries, simulates restart, verifies all 3 replayed into memtable with correct row countstest_replay_wal_entries_skips_already_flushed— verifies entries covered byreplay_after_wal_entry_positionare not replayedtest_replay_wal_entries_nothing_to_replay— verifies no-op when no WAL entries existmem_waltests pass with no regressions🤖 Generated with Claude Code