Schedule removal of duplicate Findings

changelogs/unreleased/292239-schedule-duplicate-findings-removal.yml

+---
+title: Schedule removal of duplicate Findings
+merge_request: 55749
+author:
+type: other

db/post_migrate/20210304133508_schedule_remove_duplicate_vulnerabilities_findings2.rb

+# frozen_string_literal: true
+
+class ScheduleRemoveDuplicateVulnerabilitiesFindings2 < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  MIGRATION = 'RemoveDuplicateVulnerabilitiesFindings'
+  DELAY_INTERVAL = 2.minutes.to_i
+  BATCH_SIZE = 5_000
+
+  disable_ddl_transaction!
+
+  class VulnerabilitiesFinding < ActiveRecord::Base
+    include ::EachBatch
+    self.table_name = "vulnerability_occurrences"
+  end
+
+  def up
+    say "Scheduling #{MIGRATION} jobs"
+    queue_background_migration_jobs_by_range_at_intervals(
+      VulnerabilitiesFinding,
+      MIGRATION,
+      DELAY_INTERVAL,
+      batch_size: BATCH_SIZE
+    )
+  end
+
+  def down
+    # no-op
+  end
+end

db/schema_migrations/20210304133508

+a6bf41632fc3d81d2c015d2d848f4e74468ec8cfeb2a2afb644fd92189e95e21
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