Merge lp:~twom/launchpad/rescans-need-join-conditions into lp:launchpad

[Tom Wardill]

Join the getLatest* queries to the Job table to prevent a full scan on access.

[Colin Watson (cjwatson)]

review: Approve

=== modified file 'lib/lp/code/model/branch.py'
--- lib/lp/code/model/branch.py	2019-01-28 18:09:21 +0000
+++ lib/lp/code/model/branch.py	2019-02-01 14:22:40 +0000
@@ -1303,7 +1303,8 @@
         latest_job = IStore(BranchJob).find(
             BranchJob,
             BranchJob.branch == self,
-            BranchJob.job_type == BranchScanJob.class_job_type).order_by(
+            BranchJob.job_type == BranchScanJob.class_job_type,
+            BranchJob.job == Job.id).order_by(
                 Desc(Job.date_finished)).first()
         return latest_job
 
 
=== modified file 'lib/lp/code/model/branchmergeproposal.py'
--- lib/lp/code/model/branchmergeproposal.py	2019-01-31 11:33:58 +0000
+++ lib/lp/code/model/branchmergeproposal.py	2019-02-01 14:22:40 +0000
@@ -1231,6 +1231,7 @@
             BranchMergeProposalJob,
             BranchMergeProposalJob.branch_merge_proposal == self,
             BranchMergeProposalJob.job_type == diff_type,
+            BranchMergeProposalJob.job == Job.id,
             ).order_by(Desc(Job.date_finished)).first()
         if latest_preview is not None:
             latest_preview = latest_preview.makeDerived()
 
=== modified file 'lib/lp/code/model/gitrepository.py'
--- lib/lp/code/model/gitrepository.py	2019-01-28 18:09:21 +0000
+++ lib/lp/code/model/gitrepository.py	2019-02-01 14:22:40 +0000
@@ -752,7 +752,8 @@
         latest_job = IStore(GitJob).find(
             GitJob,
             GitJob.repository == self,
-            GitJob.job_type == GitRefScanJob.class_job_type).order_by(
+            GitJob.job_type == GitRefScanJob.class_job_type,
+            GitJob.job == Job.id).order_by(
                 Desc(Job.date_finished)).first()
         return latest_job