diff --git a/src/sql/hydra.sql b/src/sql/hydra.sql
index d53ba11f..b2c61740 100644
--- a/src/sql/hydra.sql
+++ b/src/sql/hydra.sql
@@ -637,7 +637,7 @@ create index IndexBuildsOnJobset on Builds(project, jobset);
 create index IndexBuildsOnProject on Builds(project);
 create index IndexBuildsOnTimestamp on Builds(timestamp);
 create index IndexBuildsOnFinishedStopTime on Builds(finished, stoptime DESC);
-create index IndexBuildsOnJobFinishedId on builds(project, jobset, job, system, finished, id DESC);
+create index IndexBuildsOnJobFinishedId on builds(project, jobset, job, system, finished, id DESC) where finished = 0;
 create index IndexBuildsOnDrvPath on Builds(drvPath);
 create index IndexCachedHgInputsOnHash on CachedHgInputs(uri, branch, sha256hash);
 create index IndexCachedGitInputsOnHash on CachedGitInputs(uri, branch, sha256hash);
diff --git a/src/sql/upgrade-47.sql b/src/sql/upgrade-47.sql
new file mode 100644
index 00000000..3585b6a6
--- /dev/null
+++ b/src/sql/upgrade-47.sql
@@ -0,0 +1,2 @@
+drop index IndexBuildsOnJobFinishedId;
+create index IndexBuildsOnJobFinishedId on builds(project, jobset, job, system, finished, id DESC) where finished = 0;