diff --git a/src/sql/hydra.sql b/src/sql/hydra.sql
index 459305df..26617789 100644
--- a/src/sql/hydra.sql
+++ b/src/sql/hydra.sql
@@ -609,6 +609,7 @@ create table RunCommandLogs (
     -- core_dumped must not be null. However, these semantics are tricky
     -- to encode as constraints and probably provide limited actual value.
 );
+create index IndexRunCommandLogsOnBuildID on RunCommandLogs(build_id);
 
 -- The output paths that have permanently failed.
 create table FailedPaths (
diff --git a/src/sql/upgrade-81.sql b/src/sql/upgrade-81.sql
index 8e6adc43..d7dcb519 100644
--- a/src/sql/upgrade-81.sql
+++ b/src/sql/upgrade-81.sql
@@ -2,3 +2,4 @@ alter table runcommandlogs add column uuid uuid;
 update runcommandlogs set uuid = gen_random_uuid() where uuid is null;
 alter table runcommandlogs alter column uuid set not null;
 alter table runcommandlogs add constraint RunCommandLogs_uuid_unique unique(uuid);
+create index IndexRunCommandLogsOnBuildID on RunCommandLogs(build_id);