1 files changed, 28 insertions, 0 deletions
diff --git a/db/migrate/20221209174157_truncate_sbom_occurrences.rb b/db/migrate/20221209174157_truncate_sbom_occurrences.rb
new file mode 100644
index 00000000000..e9db6526e2d
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+++ b/db/migrate/20221209174157_truncate_sbom_occurrences.rb
@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+class TruncateSbomOccurrences < Gitlab::Database::Migration[2.1]
+  def up
+    # Because existing data in the table violates the new
+    # uniqueness constraints, we need to remove the non-distinct rows.
+    # Rather than do an expensive and error-prone batch migration
+    # to find and remove the duplicates, we'll just remove all records
+    # from the table.
+    #
+    # The `cyclonedx_sbom_ingestion` feature flag should
+    # be OFF in all environments to avoid having more duplicate records
+    # added between this migration and the one where the new unqiue index
+    # is added.
+
+    # TRUNCATE is a DDL statement (it drops the table and re-creates it), so we want to run the
+    # migration in DDL mode, but we also don't want to execute it against all schemas because
+    # it's considered a write operation. So, we'll manually check and skip the migration if
+    # it's on not `:gitlab_main`.
+    return unless Gitlab::Database.gitlab_schemas_for_connection(connection).include?(:gitlab_main)
+
+    execute('TRUNCATE sbom_occurrences')
+  end
+
+  def down
+    # no-op
+  end
+end