releases:merge-names: keyset paging on (created_at, set_id)

Sets stored in one batch share created_at, so paging on created_at < last
skipped ~10k of 61k sets; the timestamp now also stays text so microseconds
survive the round trip.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

commands/releases_merge_names.ts

@@ -20,16 +20,20 @@ export default class ReleasesMergeNames extends BaseCommand {
 
   async run() {
     const merger = new Par2Merger()
-    let before = '9999-12-31'
+    // Keyset on (newest created_at, set_id): sets stored in one batch share created_at, and the timestamp stays text
+    // so microseconds survive the round trip.
+    let before = ['9999-12-31', '']
     let looked = 0
     let merges = 0
     let releases = 0
     const examples: string[] = []
     while (this.sets === undefined || looked < this.sets) {
       const { rows } = await db.rawQuery(
-        `SELECT s.set_id, max(s.created_at) AS at FROM par2_sets s WHERE s.created_at < ? AND EXISTS (SELECT 1 FROM par2_files f WHERE f.set_id = s.set_id)
-         GROUP BY s.set_id ORDER BY at DESC LIMIT ${this.dryRun ? 50 : 500}`,
-        [before]
+        `SELECT set_id, at::text AS at FROM (
+           SELECT s.set_id, max(s.created_at) AS at FROM par2_sets s WHERE EXISTS (SELECT 1 FROM par2_files f WHERE f.set_id = s.set_id)
+           GROUP BY s.set_id) x
+         WHERE (at, set_id) < (?::timestamptz, ?) ORDER BY at DESC, set_id DESC LIMIT ${this.dryRun ? 50 : 500}`,
+        before
       )
       if (rows.length === 0) break
       for (const { set_id: setId } of rows) {
@@ -52,7 +56,7 @@ export default class ReleasesMergeNames extends BaseCommand {
           }
         }
       }
-      before = rows.at(-1).at
+      before = [rows.at(-1).at, rows.at(-1).set_id]
       if (this.dryRun || looked % 20_000 < 500) this.logger.info(`${looked} sets looked at: ${releases} releases ${this.dryRun ? 'would merge' : 'merged'} into ${merges}.`)
     }
     this.logger.info(`Done: ${looked} sets looked at, ${releases} releases ${this.dryRun ? 'would merge' : 'merged'} into ${merges}.`)