Optimize GC query join a bit by reducing the surface

We remove the directly referenced images from the join across ancestors, as they will be covered by the first part of the union clause. For some large repositories, this will result in a significantly reduced set of images that have to be joined NxM.
This commit is contained in:
Joseph Schorr 2017-06-09 12:16:34 -04:00
parent f0dd2e348b
commit d68b65d90c
2 changed files with 43 additions and 6 deletions

View file

@ -194,17 +194,21 @@ def garbage_collect_repo(repo, extra_candidate_set=None):
# directly referenced by a tag. This can be used in a subquery to directly
# find which candidates are being referenced without any client side
# computation or extra round trips.
direct_referenced = (RepositoryTag
.select(RepositoryTag.image)
.where(RepositoryTag.repository == repo.id,
RepositoryTag.image << candidates_orphans))
cloned = direct_referenced.clone().alias('direct_ref')
directly_referenced_subquery = Image.alias().select(cloned.c.image_id).from_(cloned)
ancestor_referenced = (Candidate
.select(Candidate.id)
.join(Tagged, on=ancestor_superset)
.join(RepositoryTag, on=(Tagged.id == RepositoryTag.image))
.where(RepositoryTag.repository == repo.id,
Candidate.id << candidates_orphans))
direct_referenced = (RepositoryTag
.select(RepositoryTag.image)
.where(RepositoryTag.repository == repo.id,
RepositoryTag.image << candidates_orphans))
Candidate.id << candidates_orphans,
~(Candidate.id << directly_referenced_subquery)))
referenced_candidates = (direct_referenced | ancestor_referenced)

View file

@ -314,38 +314,71 @@ class TestGarbageCollection(unittest.TestCase):
repository = self.createRepository(latest=['i1', 'i2', 'i3'], other=['i1', 'f1', 'f2'],
third=['t1', 't2', 't3'], fourth=['i1', 'f1'])
# Current state:
# latest -> i3->i2->i1
# other -> f2->f1->i1
# third -> t3->t2->t1
# fourth -> f1->i1
# Delete tag other. Should delete f2, since it is not shared.
self.deleteTag(repository, 'other')
self.assertDeleted(repository, 'f2')
self.assertNotDeleted(repository, 'i1', 'i2', 'i3', 't1', 't2', 't3', 'f1')
# Current state:
# latest -> i3->i2->i1
# third -> t3->t2->t1
# fourth -> f1->i1
# Move tag fourth to i3. This should remove f1 since it is no longer referenced.
self.moveTag(repository, 'fourth', 'i3')
self.assertDeleted(repository, 'f1')
self.assertNotDeleted(repository, 'i1', 'i2', 'i3', 't1', 't2', 't3')
# Current state:
# latest -> i3->i2->i1
# third -> t3->t2->t1
# fourth -> i3->i2->i1
# Delete tag 'latest'. This should do nothing since fourth is on the same branch.
self.deleteTag(repository, 'latest')
self.assertNotDeleted(repository, 'i1', 'i2', 'i3', 't1', 't2', 't3')
# Current state:
# third -> t3->t2->t1
# fourth -> i3->i2->i1
# Delete tag 'third'. This should remove t1->t3.
self.deleteTag(repository, 'third')
self.assertDeleted(repository, 't1', 't2', 't3')
self.assertNotDeleted(repository, 'i1', 'i2', 'i3')
# Current state:
# fourth -> i3->i2->i1
# Add tag to i1.
self.moveTag(repository, 'newtag', 'i1')
self.assertNotDeleted(repository, 'i1', 'i2', 'i3')
# Current state:
# fourth -> i3->i2->i1
# newtag -> i1
# Delete tag 'fourth'. This should remove i2 and i3.
self.deleteTag(repository, 'fourth')
self.assertDeleted(repository, 'i2', 'i3')
self.assertNotDeleted(repository, 'i1')
# Current state:
# newtag -> i1
# Delete tag 'newtag'. This should remove the remaining image.
self.deleteTag(repository, 'newtag')
self.assertDeleted(repository, 'i1')
# Current state:
# (Empty)
def test_empty_gc(self):
with self.assert_gc_integrity(expect_storage_removed=False):
repository = self.createRepository(latest=['i1', 'i2', 'i3'], other=['i1', 'f1', 'f2'],