fragments back on the NVMe: the fragment merger reads every row, not by key

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

database/migrations/1770000003500_fragments_back_on_nvme.ts

@@ -0,0 +1,29 @@
+import { BaseSchema } from '@adonisjs/lucid/schema'
+
+/**
+ * fragments, with its indexes, back in the catalog's tablespace (default_tablespace: nvme on homelab), out of
+ * CHUNK_TABLESPACE where 3200 put it: it isn't read by key only. The fragment merger walks its file_key index and
+ * reads each row, written and deleted all the time; on the HDD one round of its 30 s budget took 12+ minutes, and the
+ * coordinator's settling and tail planning waited behind it (LOG.md 2026-10-15 (57)). 13 GB. Homelab was moved by
+ * hand first, with the writers stopped; a no-op where it's there already, or without a default tablespace (tests).
+ */
+export default class extends BaseSchema {
+  async up() {
+    this.defer(async (db) => {
+      const { rows: setting } = await db.rawQuery(`SELECT current_setting('default_tablespace') AS target`)
+      const target = setting[0].target
+      if (!target) return
+      const { rows } = await db.rawQuery(
+        `SELECT c.relname, c.relkind FROM pg_class c LEFT JOIN pg_tablespace t ON t.oid = c.reltablespace
+         WHERE (c.relname = 'fragments' OR c.oid IN (SELECT indexrelid FROM pg_index WHERE indrelid = 'fragments'::regclass))
+           AND coalesce(t.spcname, 'pg_default') <> ?`,
+        [target]
+      )
+      for (const { relname, relkind } of rows) {
+        await db.rawQuery(`ALTER ${relkind === 'i' ? 'INDEX' : 'TABLE'} ${relname} SET TABLESPACE ${target}`)
+      }
+    })
+  }
+
+  async down() {}
+}