Delete security_finding records with missing UUIDs

We will add null constraint to this table afterwards.

db/migrate/20210318134427_delete_security_findings_without_uuid.rb

+# frozen_string_literal: true
+
+class DeleteSecurityFindingsWithoutUuid < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  class SecurityFinding < ActiveRecord::Base
+    include EachBatch
+
+    self.table_name = 'security_findings'
+
+    scope :without_uuid, -> { where(uuid: nil) }
+  end
+
+  def up
+    SecurityFinding.without_uuid.each_batch(of: 10_000) do |relation|
+      relation.delete_all
+    end
+  end
+
+  def down
+    # no-op
+  end
+end

db/schema_migrations/20210318134427

+07f4619577b05ea6a62045c81de7d225841bea28c0dd8f2cdb2011c902fd3e5a
\ No newline at end of file

spec/migrations/delete_security_findings_without_uuid_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+require_migration!
+
+RSpec.describe DeleteSecurityFindingsWithoutUuid do
+  let(:users) { table(:users) }
+  let(:namespaces) { table(:namespaces) }
+  let(:projects) { table(:projects) }
+  let(:ci_pipelines) { table(:ci_pipelines) }
+  let(:ci_builds) { table(:ci_builds) }
+  let(:ci_artifacts) { table(:ci_job_artifacts) }
+  let(:scanners) { table(:vulnerability_scanners) }
+  let(:security_scans) { table(:security_scans) }
+  let(:security_findings) { table(:security_findings) }
+  let(:sast_file_type) { 5 }
+  let(:sast_scan_type) { 1 }
+
+  let(:user) { users.create!(email: 'test@gitlab.com', projects_limit: 5) }
+  let(:namespace) { namespaces.create!(name: 'gitlab', path: 'gitlab-org') }
+  let(:project) { projects.create!(namespace_id: namespace.id, name: 'foo') }
+  let(:ci_pipeline) { ci_pipelines.create!(project_id: project.id, ref: 'master', sha: 'adf43c3a', status: 'success') }
+  let(:ci_build) { ci_builds.create!(commit_id: ci_pipeline.id, retried: false, type: 'Ci::Build') }
+  let(:ci_artifact) { ci_artifacts.create!(project_id: project.id, job_id: ci_build.id, file_type: sast_file_type, file_format: 1) }
+  let(:scanner) { scanners.create!(project_id: project.id, external_id: 'bandit', name: 'Bandit') }
+  let(:security_scan) { security_scans.create!(build_id: ci_build.id, scan_type: sast_scan_type) }
+
+  let!(:finding_1) { security_findings.create!(scan_id: security_scan.id, scanner_id: scanner.id, severity: 0, confidence: 0, project_fingerprint: Digest::SHA1.hexdigest(SecureRandom.uuid)) }
+  let!(:finding_2) { security_findings.create!(scan_id: security_scan.id, scanner_id: scanner.id, severity: 0, confidence: 0, project_fingerprint: Digest::SHA1.hexdigest(SecureRandom.uuid), uuid: SecureRandom.uuid) }
+
+  it 'successfully runs and does not schedule any job' do
+    expect { migrate! }.to change { described_class::SecurityFinding.count }.by(-1)
+                       .and change { described_class::SecurityFinding.where(id: finding_1) }
+  end
+end