diff --git a/pkg/installer/installer.go b/pkg/installer/installer.go
index 6f994ac0..f7c8cee2 100644
--- a/pkg/installer/installer.go
+++ b/pkg/installer/installer.go
@@ -92,6 +92,50 @@ func NewLuetInstaller(concurrency int) Installer {
 	return &LuetInstaller{Concurrency: concurrency}
 }
 
+func (l *LuetInstaller) Upgrade(s *System) error {
+	Spinner(32)
+	defer SpinnerStop()
+	syncedRepos := Repositories{}
+	for _, r := range l.PackageRepositories {
+		repo, err := r.Sync()
+		if err != nil {
+			return errors.Wrap(err, "Failed syncing repository: "+r.GetName())
+		}
+		syncedRepos = append(syncedRepos, repo)
+	}
+
+	// compute what to install and from where
+	sort.Sort(syncedRepos)
+
+	// First match packages against repositories by priority
+	//	matches := syncedRepos.PackageMatches(p)
+
+	// compute a "big" world
+	allRepos := pkg.NewInMemoryDatabase(false)
+	syncedRepos.SyncDatabase(allRepos)
+	solv := solver.NewSolver(s.Database, allRepos, pkg.NewInMemoryDatabase(false))
+	uninstall, solution, err := solv.Upgrade()
+	if err != nil {
+		return errors.Wrap(err, "Failed solving solution for upgrade")
+	}
+
+	for _, u := range uninstall {
+		err := l.Uninstall(u, s)
+		if err != nil {
+			Warning("Failed uninstall for ", u.GetFingerPrint())
+		}
+	}
+
+	toInstall := []pkg.Package{}
+	for _, assertion := range solution {
+		if assertion.Value {
+			toInstall = append(toInstall, assertion.Package)
+		}
+	}
+
+	return l.Install(toInstall, s)
+}
+
 func (l *LuetInstaller) Install(p []pkg.Package, s *System) error {
 	// First get metas from all repos (and decodes trees)
 
@@ -136,8 +180,10 @@ func (l *LuetInstaller) Install(p []pkg.Package, s *System) error {
 
 				}
 				if matches[0].Package.Matches(artefact.GetCompileSpec().GetPackage()) {
-					// TODO: Filter out already installed?
-					toInstall[assertion.Package.GetFingerPrint()] = ArtifactMatch{Package: assertion.Package, Artifact: artefact, Repository: matches[0].Repo}
+					// Filter out already installed
+					if _, err := s.Database.FindPackage(assertion.Package); err != nil {
+						toInstall[assertion.Package.GetFingerPrint()] = ArtifactMatch{Package: assertion.Package, Artifact: artefact, Repository: matches[0].Repo}
+					}
 					break A
 				}
 			}
diff --git a/pkg/installer/installer_test.go b/pkg/installer/installer_test.go
index a33d766f..16a6e8cc 100644
--- a/pkg/installer/installer_test.go
+++ b/pkg/installer/installer_test.go
@@ -257,4 +257,116 @@ uri: "`+tmpdir+`"
 		})
 
 	})
+
+	Context("Simple upgrades", func() {
+		It("Installs packages and Upgrades a system with a persistent db", func() {
+			//repo:=NewLuetRepository()
+
+			tmpdir, err := ioutil.TempDir("", "tree")
+			Expect(err).ToNot(HaveOccurred())
+			defer os.RemoveAll(tmpdir) // clean up
+
+			generalRecipe := tree.NewCompilerRecipe(pkg.NewInMemoryDatabase(false))
+
+			err = generalRecipe.Load("../../tests/fixtures/upgrade")
+			Expect(err).ToNot(HaveOccurred())
+
+			Expect(len(generalRecipe.GetDatabase().GetPackages())).To(Equal(4))
+
+			c := compiler.NewLuetCompiler(backend.NewSimpleDockerBackend(), generalRecipe.GetDatabase())
+
+			spec, err := c.FromPackage(&pkg.DefaultPackage{Name: "b", Category: "test", Version: "1.0"})
+			Expect(err).ToNot(HaveOccurred())
+			spec2, err := c.FromPackage(&pkg.DefaultPackage{Name: "b", Category: "test", Version: "1.1"})
+			Expect(err).ToNot(HaveOccurred())
+			spec3, err := c.FromPackage(&pkg.DefaultPackage{Name: "c", Category: "test", Version: "1.0"})
+			Expect(err).ToNot(HaveOccurred())
+
+			Expect(spec.GetPackage().GetPath()).ToNot(Equal(""))
+
+			tmpdir, err = ioutil.TempDir("", "tree")
+			Expect(err).ToNot(HaveOccurred())
+			defer os.RemoveAll(tmpdir) // clean up
+
+			spec.SetOutputPath(tmpdir)
+			spec2.SetOutputPath(tmpdir)
+			spec3.SetOutputPath(tmpdir)
+			_, errs := c.CompileParallel(2, false, compiler.NewLuetCompilationspecs(spec, spec2, spec3))
+
+			Expect(errs).To(BeEmpty())
+
+			repo, err := GenerateRepository("test", tmpdir, "local", 1, tmpdir, "../../tests/fixtures/upgrade", pkg.NewInMemoryDatabase(false))
+			Expect(err).ToNot(HaveOccurred())
+			Expect(repo.GetName()).To(Equal("test"))
+			Expect(helpers.Exists(spec.Rel("repository.yaml"))).ToNot(BeTrue())
+			Expect(helpers.Exists(spec.Rel("tree.tar"))).ToNot(BeTrue())
+			err = repo.Write(tmpdir)
+			Expect(err).ToNot(HaveOccurred())
+
+			Expect(helpers.Exists(spec.Rel("repository.yaml"))).To(BeTrue())
+			Expect(helpers.Exists(spec.Rel("tree.tar"))).To(BeTrue())
+			Expect(repo.GetUri()).To(Equal(tmpdir))
+			Expect(repo.GetType()).To(Equal("local"))
+
+			fakeroot, err := ioutil.TempDir("", "fakeroot")
+			Expect(err).ToNot(HaveOccurred())
+			defer os.RemoveAll(fakeroot) // clean up
+
+			inst := NewLuetInstaller(1)
+			repo2, err := NewLuetRepositoryFromYaml([]byte(`
+name: "test"
+type: "local"
+uri: "`+tmpdir+`"
+`), pkg.NewInMemoryDatabase(false))
+			Expect(err).ToNot(HaveOccurred())
+
+			inst.Repositories(Repositories{repo2})
+			Expect(repo.GetUri()).To(Equal(tmpdir))
+			Expect(repo.GetType()).To(Equal("local"))
+
+			bolt, err := ioutil.TempDir("", "db")
+			Expect(err).ToNot(HaveOccurred())
+			defer os.RemoveAll(bolt) // clean up
+
+			systemDB := pkg.NewBoltDatabase(filepath.Join(bolt, "db.db"))
+			system := &System{Database: systemDB, Target: fakeroot}
+			err = inst.Install([]pkg.Package{&pkg.DefaultPackage{Name: "b", Category: "test", Version: "1.0"}}, system)
+			Expect(err).ToNot(HaveOccurred())
+
+			Expect(helpers.Exists(filepath.Join(fakeroot, "test5"))).To(BeTrue())
+			Expect(helpers.Exists(filepath.Join(fakeroot, "test6"))).To(BeTrue())
+			_, err = systemDB.FindPackage(&pkg.DefaultPackage{Name: "b", Category: "test", Version: "1.0"})
+			Expect(err).ToNot(HaveOccurred())
+
+			Expect(len(system.Database.GetPackages())).To(Equal(1))
+			p, err := system.Database.GetPackage(system.Database.GetPackages()[0])
+			Expect(err).ToNot(HaveOccurred())
+			Expect(p.GetName()).To(Equal("b"))
+
+			files, err := systemDB.GetPackageFiles(&pkg.DefaultPackage{Name: "b", Category: "test", Version: "1.0"})
+			Expect(files).To(Equal([]string{"artifact42", "test5", "test6"}))
+			Expect(err).ToNot(HaveOccurred())
+
+			err = inst.Upgrade(system)
+			Expect(err).ToNot(HaveOccurred())
+
+			// Nothing should be there anymore (files, packagedb entry)
+			Expect(helpers.Exists(filepath.Join(fakeroot, "test5"))).ToNot(BeTrue())
+			Expect(helpers.Exists(filepath.Join(fakeroot, "test6"))).ToNot(BeTrue())
+
+			// New version - new files
+			Expect(helpers.Exists(filepath.Join(fakeroot, "newc"))).To(BeTrue())
+			_, err = system.Database.GetPackageFiles(&pkg.DefaultPackage{Name: "b", Category: "test", Version: "1.0"})
+			Expect(err).To(HaveOccurred())
+			_, err = system.Database.FindPackage(&pkg.DefaultPackage{Name: "b", Category: "test", Version: "1.0"})
+			Expect(err).To(HaveOccurred())
+
+			// New package should be there
+			_, err = system.Database.FindPackage(&pkg.DefaultPackage{Name: "b", Category: "test", Version: "1.1"})
+			Expect(err).ToNot(HaveOccurred())
+
+		})
+
+	})
+
 })
diff --git a/pkg/installer/interface.go b/pkg/installer/interface.go
index e2a9a5fc..374b23d2 100644
--- a/pkg/installer/interface.go
+++ b/pkg/installer/interface.go
@@ -25,6 +25,7 @@ import (
 type Installer interface {
 	Install([]pkg.Package, *System) error
 	Uninstall(pkg.Package, *System) error
+	Upgrade(s *System) error
 	Repositories([]Repository)
 }
 
diff --git a/pkg/solver/solver.go b/pkg/solver/solver.go
index f6bf9590..42a0061a 100644
--- a/pkg/solver/solver.go
+++ b/pkg/solver/solver.go
@@ -32,6 +32,7 @@ type PackageSolver interface {
 	ConflictsWithInstalled(p pkg.Package) (bool, error)
 	ConflictsWith(p pkg.Package, ls []pkg.Package) (bool, error)
 	World() []pkg.Package
+	Upgrade() ([]pkg.Package, PackagesAssertions, error)
 }
 
 // Solver is the default solver for luet
@@ -193,6 +194,55 @@ func (s *Solver) ConflictsWithInstalled(p pkg.Package) (bool, error) {
 	return s.ConflictsWith(p, s.Installed())
 }
 
+func (s *Solver) Upgrade() ([]pkg.Package, PackagesAssertions, error) {
+
+	// First get candidates that needs to be upgraded..
+
+	toUninstall := []pkg.Package{}
+	toInstall := []pkg.Package{}
+
+	availableCache := map[string][]pkg.Package{}
+	for _, p := range s.DefinitionDatabase.World() {
+		// Each one, should be expanded
+		availableCache[p.GetName()+p.GetCategory()] = append(availableCache[p.GetName()+p.GetCategory()], p)
+	}
+
+	installedcopy := pkg.NewInMemoryDatabase(false)
+
+	for _, p := range s.InstalledDatabase.World() {
+		installedcopy.CreatePackage(p)
+		packages, ok := availableCache[p.GetName()+p.GetCategory()]
+		if ok && len(packages) != 0 {
+			best := pkg.Best(packages)
+			if best.GetVersion() != p.GetVersion() {
+				toUninstall = append(toUninstall, p)
+				toInstall = append(toInstall, best)
+			}
+		}
+	}
+
+	s2 := NewSolver(installedcopy, s.DefinitionDatabase, pkg.NewInMemoryDatabase(false))
+	// Then try to uninstall the versions in the system, and store that tree
+	for _, p := range toUninstall {
+		r, err := s.Uninstall(p)
+		if err != nil {
+			return nil, nil, errors.Wrap(err, "Could not compute upgrade - couldn't uninstall selected candidate "+p.GetFingerPrint())
+		}
+		for _, z := range r {
+			err = installedcopy.RemovePackage(z)
+			if err != nil {
+				return nil, nil, errors.Wrap(err, "Could not compute upgrade - couldn't remove copy of package targetted for removal")
+			}
+		}
+
+	}
+	r, e := s2.Install(toInstall)
+	return toUninstall, r, e
+	// To that tree, ask to install the versions that should be upgraded, and try to solve
+	// Return the solution
+
+}
+
 // Uninstall takes a candidate package and return a list of packages that would be removed
 // in order to purge the candidate. Returns error if unsat.
 func (s *Solver) Uninstall(c pkg.Package) ([]pkg.Package, error) {
diff --git a/pkg/solver/solver_test.go b/pkg/solver/solver_test.go
index 0f5a3644..b18e75ca 100644
--- a/pkg/solver/solver_test.go
+++ b/pkg/solver/solver_test.go
@@ -678,5 +678,39 @@ var _ = Describe("Solver", func() {
 			Expect(p).To(Equal(a03))
 		})
 	})
+	Context("Upgrades", func() {
 
+		C := pkg.NewPackage("c", "1.5", []*pkg.DefaultPackage{&pkg.DefaultPackage{Name: "a", Version: ">=1.0", Category: "test"}}, []*pkg.DefaultPackage{})
+		C.SetCategory("test")
+		B := pkg.NewPackage("b", "1.0", []*pkg.DefaultPackage{}, []*pkg.DefaultPackage{})
+		B.SetCategory("test")
+		A := pkg.NewPackage("a", "1.1", []*pkg.DefaultPackage{&pkg.DefaultPackage{Name: "b", Version: "1.0", Category: "test"}}, []*pkg.DefaultPackage{})
+		A.SetCategory("test")
+		A1 := pkg.NewPackage("a", "1.2", []*pkg.DefaultPackage{&pkg.DefaultPackage{Name: "b", Version: "1.0", Category: "test"}}, []*pkg.DefaultPackage{})
+		A1.SetCategory("test")
+
+		It("upgrades correctly", func() {
+			for _, p := range []pkg.Package{A1, B, C} {
+				_, err := dbDefinitions.CreatePackage(p)
+				Expect(err).ToNot(HaveOccurred())
+			}
+
+			for _, p := range []pkg.Package{A, B} {
+				_, err := dbInstalled.CreatePackage(p)
+				Expect(err).ToNot(HaveOccurred())
+			}
+			uninstall, solution, err := s.Upgrade()
+			Expect(err).ToNot(HaveOccurred())
+
+			Expect(len(uninstall)).To(Equal(1))
+			Expect(uninstall[0].GetName()).To(Equal("a"))
+			Expect(uninstall[0].GetVersion()).To(Equal("1.1"))
+
+			Expect(solution).To(ContainElement(PackageAssert{Package: A1, Value: true}))
+			Expect(solution).To(ContainElement(PackageAssert{Package: B, Value: true}))
+			Expect(solution).To(ContainElement(PackageAssert{Package: C, Value: false}))
+			Expect(len(solution)).To(Equal(3))
+
+		})
+	})
 })
diff --git a/tests/fixtures/upgrade/c/build.yaml b/tests/fixtures/upgrade/c/build.yaml
new file mode 100644
index 00000000..dc3fba0a
--- /dev/null
+++ b/tests/fixtures/upgrade/c/build.yaml
@@ -0,0 +1,10 @@
+prelude:
+  - echo foo > /test
+  - echo bar > /test2
+steps:
+  - echo c > /c
+  - echo c > /cd
+requires:
+- category: "test"
+  name: "a"
+  version: ">=1.0"
diff --git a/tests/fixtures/upgrade/c/definition.yaml b/tests/fixtures/upgrade/c/definition.yaml
new file mode 100644
index 00000000..348454f7
--- /dev/null
+++ b/tests/fixtures/upgrade/c/definition.yaml
@@ -0,0 +1,3 @@
+category: "test"
+name: "c"
+version: "1.0"
diff --git a/tests/fixtures/upgrade/cat/a/a/build.yaml b/tests/fixtures/upgrade/cat/a/a/build.yaml
new file mode 100644
index 00000000..b9fe4c1d
--- /dev/null
+++ b/tests/fixtures/upgrade/cat/a/a/build.yaml
@@ -0,0 +1,11 @@
+image: "alpine"
+prelude:
+  - echo foo > /test
+  - echo bar > /test2
+steps:
+  - echo artifact3 > /test3
+  - echo artifact4 > /test4
+requires:
+- category: "test"
+  name: "b"
+  version: "1.0"
diff --git a/tests/fixtures/upgrade/cat/a/a/definition.yaml b/tests/fixtures/upgrade/cat/a/a/definition.yaml
new file mode 100644
index 00000000..a419363d
--- /dev/null
+++ b/tests/fixtures/upgrade/cat/a/a/definition.yaml
@@ -0,0 +1,8 @@
+category: "test"
+name: "a"
+version: "1.1"
+requires:
+- category: "test2"
+  name: "b"
+  version: "1.0"
+
diff --git a/tests/fixtures/upgrade/cat/b-1.1/build.yaml b/tests/fixtures/upgrade/cat/b-1.1/build.yaml
new file mode 100644
index 00000000..3e3f98a4
--- /dev/null
+++ b/tests/fixtures/upgrade/cat/b-1.1/build.yaml
@@ -0,0 +1,9 @@
+image: "alpine"
+prelude:
+  - echo foo > /test
+  - echo bar > /test2
+  - chmod +x generate.sh
+steps:
+  - echo artifact5 > /newc
+  - echo artifact6 > /newnewc
+  - ./generate.sh
diff --git a/tests/fixtures/upgrade/cat/b-1.1/definition.yaml b/tests/fixtures/upgrade/cat/b-1.1/definition.yaml
new file mode 100644
index 00000000..e695c6c9
--- /dev/null
+++ b/tests/fixtures/upgrade/cat/b-1.1/definition.yaml
@@ -0,0 +1,3 @@
+category: "test"
+name: "b"
+version: "1.1"
diff --git a/tests/fixtures/upgrade/cat/b-1.1/generate.sh b/tests/fixtures/upgrade/cat/b-1.1/generate.sh
new file mode 100644
index 00000000..3b2dc1b2
--- /dev/null
+++ b/tests/fixtures/upgrade/cat/b-1.1/generate.sh
@@ -0,0 +1 @@
+echo generated > /sonewc
diff --git a/tests/fixtures/upgrade/cat/b/build.yaml b/tests/fixtures/upgrade/cat/b/build.yaml
new file mode 100644
index 00000000..05a81578
--- /dev/null
+++ b/tests/fixtures/upgrade/cat/b/build.yaml
@@ -0,0 +1,9 @@
+image: "alpine"
+prelude:
+  - echo foo > /test
+  - echo bar > /test2
+  - chmod +x generate.sh
+steps:
+  - echo artifact5 > /test5
+  - echo artifact6 > /test6
+  - ./generate.sh
\ No newline at end of file
diff --git a/tests/fixtures/upgrade/cat/b/definition.yaml b/tests/fixtures/upgrade/cat/b/definition.yaml
new file mode 100644
index 00000000..b02a44e8
--- /dev/null
+++ b/tests/fixtures/upgrade/cat/b/definition.yaml
@@ -0,0 +1,3 @@
+category: "test"
+name: "b"
+version: "1.0"
diff --git a/tests/fixtures/upgrade/cat/b/generate.sh b/tests/fixtures/upgrade/cat/b/generate.sh
new file mode 100644
index 00000000..b67417f6
--- /dev/null
+++ b/tests/fixtures/upgrade/cat/b/generate.sh
@@ -0,0 +1 @@
+echo generated > /artifact42