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Finger was a merge-join metaphor that hid the type's job: a monotonic forward scan over index_rows that answers btree shadow checks. Fold index_rows_epoch into the type so MvccLazyCursor no longer carries a second field that must stay in sync with the scan position. Tests: cargo test -p turso_core test_index_shadow_scan_no_spurious_dep_on_stepped_over_key Co-authored-by: Pere Diaz Bou <pereman2@users.noreply.github.com>
The seed block exists so the skiplist guard drops before later db borrows. There is no step method. Co-authored-by: Pere Diaz Bou <pereman2@users.noreply.github.com>
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Problem statement
Forward index scans used
IndexShadowFingeras a merge cursor overindex_rows. It moves with the B-tree cursor and answers whether an MVCC version hides that B-tree row, instead of callingindex_rows.get()on every row.Finger is a merge-join name. It collides with fingerprint, and the original merge joked about
_fingering_ on index rows.MvccLazyCursoralso storedindex_finger_epochbeside it. Those two fields had to stay in sync.Changes
I renamed the type to
IndexShadowScanand moved the epoch onto it. The cursor now has one field,index_shadow_scan. Callers and the tursodatabase#7504 and tursodatabase#7578 tests use the new name.Seek and backward scans still call
query_btree_version_is_valid.