-- opslog:rewrites-data
-- Normalise stored callsigns so lookups can use idx_qso_callsign.
--
-- WorkedBefore matched rows with `upper(trim(callsign)) = ?`. Wrapping the
-- column in functions makes the predicate non-sargable: SQLite cannot use the
-- index and falls back to scanning. Measured on a 190 000-row logbook, the
-- COUNT went from 0.3 ms (SEARCH ... USING INDEX) to 20.8 ms (SCAN), and the
-- entries query — which needs every column, so not even a covering index helps
-- — scans the whole table. That runs on every keystroke of a callsign, and it
-- made the entry strip's history arrive too late to auto-fill the name and
-- locator from the previous QSO. Small logbooks never showed it.
--
-- Add, bulk insert and Update have always upper-cased and trimmed the callsign,
-- so this only rewrites rows left by older versions or foreign imports, and the
-- queries can then compare the column directly.
--
-- SQLite compares case-sensitively, so the WHERE finds exactly the rows that
-- need it. MySQL's default collation is case- and trailing-space-insensitive:
-- there the UPDATE is largely a no-op and equally unnecessary, because `=`
-- already matches those rows through the index.
UPDATE qso SET callsign = upper(trim(callsign))
 WHERE callsign <> upper(trim(callsign));
