diff --git a/database/migrations/1770000004500_probe_cache_pkey_on_nvme.ts b/database/migrations/1770000004500_probe_cache_pkey_on_nvme.ts
new file mode 100644
index 0000000..b897de8
--- /dev/null
+++ b/database/migrations/1770000004500_probe_cache_pkey_on_nvme.ts
@@ -0,0 +1,26 @@
+import { BaseSchema } from '@adonisjs/lucid/schema'
+
+/**
+ * probe_cache's primary key in the catalog's tablespace (default_tablespace: nvme on homelab); the table stays on the
+ * HDD. Each claim looks its candidates up by message_id (`message_id = ANY(…)`): with the index on the HDD that took
+ * 1.27 s a claim, 48 s of each minute, the prober's lanes waiting on claims (LOG.md 2026-10-18 (76)). ~97% aren't in it,
+ * so only the index is read. Homelab moved it by hand (prober 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 1 FROM pg_class c LEFT JOIN pg_tablespace t ON t.oid = c.reltablespace
+         WHERE c.relname = 'probe_cache_pkey' AND coalesce(t.spcname, 'pg_default') <> ?`,
+        [target]
+      )
+      if (rows.length > 0) await db.rawQuery(`ALTER INDEX probe_cache_pkey SET TABLESPACE ${target}`)
+    })
+  }
+
+  async down() {}
+}