From 06a64cdd2caeda65d4367e3ea7c8ae92f186ac9f Mon Sep 17 00:00:00 2001
From: Tomas Touceda <chiiph@gmail.com>
Date: Thu, 23 Dec 2021 15:45:50 -0300
Subject: [PATCH] Use id instead of seen time/created_at to sort hosts (#3482)

* Use id instead of seen time/created_at to sort hosts

* Add test for ordering by id
---
 changes/use-index-for-sorting-hosts  | 1 +
 server/datastore/mysql/hosts.go      | 2 +-
 server/datastore/mysql/hosts_test.go | 7 +++++++
 3 files changed, 9 insertions(+), 1 deletion(-)
 create mode 100644 changes/use-index-for-sorting-hosts

diff --git a/changes/use-index-for-sorting-hosts b/changes/use-index-for-sorting-hosts
new file mode 100644
index 0000000000..8b5c8cf0dc
--- /dev/null
+++ b/changes/use-index-for-sorting-hosts
@@ -0,0 +1 @@
+* Improve performance of sorting hosts in certain scenarios.
diff --git a/server/datastore/mysql/hosts.go b/server/datastore/mysql/hosts.go
index b293efdc0c..1f2077bc01 100644
--- a/server/datastore/mysql/hosts.go
+++ b/server/datastore/mysql/hosts.go
@@ -816,7 +816,7 @@ func (d *Datastore) SearchHosts(ctx context.Context, filter fleet.TeamFilter, qu
 	args = append(args, in)
 	sqlb.WriteString(" id NOT IN (?) AND ")
 	sqlb.WriteString(d.whereFilterHostsByTeams(filter, "h"))
-	sqlb.WriteString(` ORDER BY COALESCE(hst.seen_time, h.created_at) DESC LIMIT 10`)
+	sqlb.WriteString(` ORDER BY h.id DESC LIMIT 10`)
 
 	sql, args, err := sqlx.In(sqlb.String(), args...)
 	if err != nil {
diff --git a/server/datastore/mysql/hosts_test.go b/server/datastore/mysql/hosts_test.go
index 16d1c1817f..bd439913e3 100644
--- a/server/datastore/mysql/hosts_test.go
+++ b/server/datastore/mysql/hosts_test.go
@@ -1017,6 +1017,13 @@ func testHostsSearch(t *testing.T, ds *Datastore) {
 	assert.Nil(t, err)
 	require.Len(t, hosts, 1)
 	assert.Equal(t, hosts[0].ID, h2.ID)
+
+	// sorted by ids desc
+	filter = fleet.TeamFilter{User: userObs, IncludeObserver: true}
+	hits, err = ds.SearchHosts(context.Background(), filter, "")
+	require.NoError(t, err)
+	assert.Len(t, hits, 3)
+	assert.Equal(t, []uint{h3.ID, h2.ID, h1.ID}, []uint{hits[0].ID, hits[1].ID, hits[2].ID})
 }
 
 func testHostsSearchLimit(t *testing.T, ds *Datastore) {