1 files changed, 82 insertions, 0 deletions
diff --git a/db/post_migrate/20230419094939_swap_merge_request_metrics_id_to_bigint_for_self_hosts.rb b/db/post_migrate/20230419094939_swap_merge_request_metrics_id_to_bigint_for_self_hosts.rb
new file mode 100644
index 00000000000..d249ffb9c1b
--- /dev/null
+++ b/db/post_migrate/20230419094939_swap_merge_request_metrics_id_to_bigint_for_self_hosts.rb
@@ -0,0 +1,82 @@
+# frozen_string_literal: true
+
+class SwapMergeRequestMetricsIdToBigintForSelfHosts < Gitlab::Database::Migration[2.1]
+  include Gitlab::Database::MigrationHelpers::ConvertToBigint
+
+  disable_ddl_transaction!
+
+  TABLE_NAME = 'merge_request_metrics'
+  TMP_INDEX_NAME = 'tmp_index_mr_metrics_on_target_project_id_merged_at_nulls_last'
+  INDEX_NAME = 'index_mr_metrics_on_target_project_id_merged_at_nulls_last'
+  CONSTRAINT_NAME = 'merge_request_metrics_pkey'
+
+  def up
+    return if should_skip?
+    return if temporary_column_already_dropped?
+    return if columns_alredy_swapped?
+
+    swap
+  end
+
+  def down
+    return if should_skip?
+    return if temporary_column_already_dropped?
+    return unless columns_alredy_swapped?
+
+    swap
+  end
+
+  private
+
+  def swap
+    add_concurrent_index TABLE_NAME, :id_convert_to_bigint, unique: true,
+      name: 'index_merge_request_metrics_on_id_convert_to_bigint'
+    add_concurrent_index TABLE_NAME, 'target_project_id, merged_at DESC NULLS LAST, id_convert_to_bigint DESC',
+      name: TMP_INDEX_NAME
+
+    with_lock_retries(raise_on_exhaustion: true) do
+      execute "LOCK TABLE #{TABLE_NAME} IN ACCESS EXCLUSIVE MODE"
+
+      execute "ALTER TABLE #{TABLE_NAME} RENAME COLUMN id TO id_tmp"
+      execute "ALTER TABLE #{TABLE_NAME} RENAME COLUMN id_convert_to_bigint TO id"
+      execute "ALTER TABLE #{TABLE_NAME} RENAME COLUMN id_tmp TO id_convert_to_bigint"
+
+      function_name = Gitlab::Database::UnidirectionalCopyTrigger
+        .on_table(TABLE_NAME, connection: connection)
+        .name(:id, :id_convert_to_bigint)
+      execute "ALTER FUNCTION #{quote_table_name(function_name)} RESET ALL"
+
+      # Swap defaults of the columns, and change ownership of the sequence to the new id
+      execute "ALTER SEQUENCE merge_request_metrics_id_seq OWNED BY #{TABLE_NAME}.id"
+      change_column_default TABLE_NAME, :id, -> { "nextval('merge_request_metrics_id_seq'::regclass)" }
+      change_column_default TABLE_NAME, :id_convert_to_bigint, 0
+
+      # Swap PK constraint
+      execute "ALTER TABLE #{TABLE_NAME} DROP CONSTRAINT IF EXISTS #{CONSTRAINT_NAME}"
+      rename_index TABLE_NAME, 'index_merge_request_metrics_on_id_convert_to_bigint', CONSTRAINT_NAME
+      execute "ALTER TABLE #{TABLE_NAME} ADD CONSTRAINT #{CONSTRAINT_NAME} PRIMARY KEY USING INDEX #{CONSTRAINT_NAME}"
+
+      # Rename the rest of the indexes (we already hold an exclusive lock, so no need to use DROP INDEX CONCURRENTLY)
+      execute "DROP INDEX IF EXISTS #{INDEX_NAME}"
+      rename_index TABLE_NAME, TMP_INDEX_NAME, INDEX_NAME
+    end
+  end
+
+  def should_skip?
+    com_or_dev_or_test_but_not_jh?
+  end
+
+  def columns_alredy_swapped?
+    table_columns = columns(TABLE_NAME)
+    column_id = table_columns.find { |c| c.name == 'id' }
+    column_id_convert_to_bigint = table_columns.find { |c| c.name == 'id_convert_to_bigint' }
+
+    column_id.sql_type == 'bigint' && column_id_convert_to_bigint.sql_type == 'integer'
+  end
+
+  def temporary_column_already_dropped?
+    table_columns = columns(TABLE_NAME)
+
+    !table_columns.find { |c| c.name == 'id_convert_to_bigint' }
+  end
+end