Expand description
Persistent backing for logical btree value indexes.
The engine still uses its in-memory uqa_storage::BTreeIndex for query-time
scans, but the compact (table, field, doc_id, value) rows live in SQLite.
Reopening an engine hydrates the B-tree from these rows instead of parsing
every full document again. Writes replace the affected postings in the
active SQLite transaction as the document mutation.