Resolve deployments.fast_destroy_all N+1

Why

Lack of preloading environments in the Deployment FastDestroyAll implementation causes N+1 on SELECT on environments.

See Preload environments to resolve N+1 (#437674 - closed) issue for more.

What

• Add spec to verify N+1
• update implementation to resolve N+1

Spec details

Here's the failure output of the new spec before it was resolved by adding the preload:

Failures:

  1) Deployment.fast_destroy_all does not trigger N+1 queries
     Failure/Error: expect { project.deployments.fast_destroy_all }.not_to exceed_query_limit(control)

       Expected a maximum of 3 queries, got 4:

       Query Diff:
       -----------
       SELECT "environments".* FROM "environments"...
       -- (expected: 1, got: 2)
          WHERE "environments"."id" = 4 LIMIT 1

Finished in 5.22 seconds (files took 9.82 seconds to load)
1 example, 1 failure

Failed examples:

rspec ./spec/models/deployment_spec.rb:1541 # Deployment.fast_destroy_all does not trigger N+1 queries

SQL

Before

I didn't include all the N+1 SELECT on environments because there were a lot, so this is truncated.

[2] pry(main)> Deployment.preload(:project).find_each.map do |deployment|
  [deployment.project, deployment.ref_path]
end
  Deployment Load (1.6ms)  SELECT "deployments"."id", "deployments"."iid", "deployments"."project_id", "deployments"."environment_id", "deployments"."ref", "deployments"."tag", "deployments"."sha", "deployments"."user_id", "deployments"."deployable_type", "deployments"."created_at", "deployments"."updated_at", "deployments"."on_stop", "deployments"."status", "deployments"."finished_at", "deployments"."deployable_id", "deployments"."archived" FROM "deployments" ORDER BY "deployments"."id" ASC LIMIT 1000 /*application:console,db_config_name:main,line:(pry):4:in `each'*/
  Project Load (0.9ms)  SELECT "projects"."id", "projects"."name", "projects"."path", "projects"."description", "projects"."created_at", "projects"."updated_at", "projects"."creator_id", "projects"."namespace_id", "projects"."last_activity_at", "projects"."import_url", "projects"."visibility_level", "projects"."archived", "projects"."avatar", "projects"."merge_requests_template", "projects"."star_count", "projects"."merge_requests_rebase_enabled", "projects"."import_type", "projects"."import_source", "projects"."approvals_before_merge", "projects"."reset_approvals_on_push", "projects"."merge_requests_ff_only_enabled", "projects"."issues_template", "projects"."mirror", "projects"."mirror_last_update_at", "projects"."mirror_last_successful_update_at", "projects"."mirror_user_id", "projects"."shared_runners_enabled", "projects"."runners_token", "projects"."build_allow_git_fetch", "projects"."build_timeout", "projects"."mirror_trigger_builds", "projects"."pending_delete", "projects"."public_builds", "projects"."last_repository_check_failed", "projects"."last_repository_check_at", "projects"."only_allow_merge_if_pipeline_succeeds", "projects"."has_external_issue_tracker", "projects"."repository_storage", "projects"."repository_read_only", "projects"."request_access_enabled", "projects"."has_external_wiki", "projects"."ci_config_path", "projects"."lfs_enabled", "projects"."description_html", "projects"."only_allow_merge_if_all_discussions_are_resolved", "projects"."repository_size_limit", "projects"."printing_merge_request_link_enabled", "projects"."auto_cancel_pending_pipelines", "projects"."service_desk_enabled", "projects"."cached_markdown_version", "projects"."delete_error", "projects"."last_repository_updated_at", "projects"."disable_overriding_approvers_per_merge_request", "projects"."storage_version", "projects"."resolve_outdated_diff_discussions", "projects"."remote_mirror_available_overridden", "projects"."only_mirror_protected_branches", "projects"."pull_mirror_available_overridden", "projects"."jobs_cache_index", "projects"."external_authorization_classification_label", "projects"."mirror_overwrites_diverged_branches", "projects"."pages_https_only", "projects"."external_webhook_token", "projects"."packages_enabled", "projects"."merge_requests_author_approval", "projects"."pool_repository_id", "projects"."runners_token_encrypted", "projects"."bfg_object_map", "projects"."detected_repository_languages", "projects"."merge_requests_disable_committers_approval", "projects"."require_password_to_approve", "projects"."max_pages_size", "projects"."max_artifacts_size", "projects"."pull_mirror_branch_prefix", "projects"."remove_source_branch_after_merge", "projects"."marked_for_deletion_at", "projects"."marked_for_deletion_by_user_id", "projects"."autoclose_referenced_issues", "projects"."suggestion_commit_message", "projects"."project_namespace_id", "projects"."hidden", "projects"."organization_id" FROM "projects" WHERE "projects"."id" IN (7, 1, 5, 6, 8, 19, 29, 239, 341, 544, 996) /*application:console,db_config_name:main,line:(pry):4:in `each'*/
  Environment Load (0.3ms)  SELECT "environments".* FROM "environments" WHERE "environments"."id" = 8 LIMIT 1 /*application:console,db_config_name:main,line:/app/models/deployment.rb:432:in `ref_path'*/
  Environment Load (0.2ms)  SELECT "environments".* FROM "environments" WHERE "environments"."id" = 8 LIMIT 1 /*application:console,db_config_name:main,line:/app/models/deployment.rb:432:in `ref_path'*/
  Environment Load (0.2ms)  SELECT "environments".* FROM "environments" WHERE "environments"."id" = 8 LIMIT 1 /*application:console,db_config_name:main,line:/app/models/deployment.rb:432:in `ref_path'*/
  Environment Load (0.1ms)  SELECT "environments".* FROM "environments" WHERE "environments"."id" = 8 LIMIT 1 /*application:console,db_config_name:main,line:/app/models/deployment.rb:432:in `ref_path'*/
  Environment Load (0.1ms)  SELECT "environments".* FROM "environments" WHERE "environments"."id" = 7 LIMIT 1 /*application:console,db_config_name:main,line:/app/models/deployment.rb:432:in `ref_path'*/
  Environment Load (0.1ms)  SELECT "environments".* FROM "environments" WHERE "environments"."id" = 7 LIMIT 1 /*application:console,db_config_name:main,line:/app/models/deployment.rb:432:in `ref_path'*/
  Environment Load (0.1ms)  SELECT "environments".* FROM "environments" WHERE "environments"."id" = 7 LIMIT 1 /*application:console,db_config_name:main,line:/app/models/deployment.rb:432:in `ref_path'*/

After

The SQL generated with the new preloaded environments looks like this:

[1] pry(main)> Deployment.preload(:project, :environment).find_each.map do |deployment|
  [deployment.project, deployment.ref_path]
end
  Deployment Load (3.3ms)  SELECT "deployments"."id", "deployments"."iid", "deployments"."project_id", "deployments"."environment_id", "deployments"."ref", "deployments"."tag", "deployments"."sha", "deployments"."user_id", "deployments"."deployable_type", "deployments"."created_at", "deployments"."updated_at", "deployments"."on_stop", "deployments"."status", "deployments"."finished_at", "deployments"."deployable_id", "deployments"."archived" FROM "deployments" ORDER BY "deployments"."id" ASC LIMIT 1000 /*application:console,db_config_name:main,console_hostname:,line:(pry):1:in `each'*/
  Project Load (5.2ms)  SELECT "projects"."id", "projects"."name", "projects"."path", "projects"."description", "projects"."created_at", "projects"."updated_at", "projects"."creator_id", "projects"."namespace_id", "projects"."last_activity_at", "projects"."import_url", "projects"."visibility_level", "projects"."archived", "projects"."avatar", "projects"."merge_requests_template", "projects"."star_count", "projects"."merge_requests_rebase_enabled", "projects"."import_type", "projects"."import_source", "projects"."approvals_before_merge", "projects"."reset_approvals_on_push", "projects"."merge_requests_ff_only_enabled", "projects"."issues_template", "projects"."mirror", "projects"."mirror_last_update_at", "projects"."mirror_last_successful_update_at", "projects"."mirror_user_id", "projects"."shared_runners_enabled", "projects"."runners_token", "projects"."build_allow_git_fetch", "projects"."build_timeout", "projects"."mirror_trigger_builds", "projects"."pending_delete", "projects"."public_builds", "projects"."last_repository_check_failed", "projects"."last_repository_check_at", "projects"."only_allow_merge_if_pipeline_succeeds", "projects"."has_external_issue_tracker", "projects"."repository_storage", "projects"."repository_read_only", "projects"."request_access_enabled", "projects"."has_external_wiki", "projects"."ci_config_path", "projects"."lfs_enabled", "projects"."description_html", "projects"."only_allow_merge_if_all_discussions_are_resolved", "projects"."repository_size_limit", "projects"."printing_merge_request_link_enabled", "projects"."auto_cancel_pending_pipelines", "projects"."service_desk_enabled", "projects"."cached_markdown_version", "projects"."delete_error", "projects"."last_repository_updated_at", "projects"."disable_overriding_approvers_per_merge_request", "projects"."storage_version", "projects"."resolve_outdated_diff_discussions", "projects"."remote_mirror_available_overridden", "projects"."only_mirror_protected_branches", "projects"."pull_mirror_available_overridden", "projects"."jobs_cache_index", "projects"."external_authorization_classification_label", "projects"."mirror_overwrites_diverged_branches", "projects"."pages_https_only", "projects"."external_webhook_token", "projects"."packages_enabled", "projects"."merge_requests_author_approval", "projects"."pool_repository_id", "projects"."runners_token_encrypted", "projects"."bfg_object_map", "projects"."detected_repository_languages", "projects"."merge_requests_disable_committers_approval", "projects"."require_password_to_approve", "projects"."max_pages_size", "projects"."max_artifacts_size", "projects"."pull_mirror_branch_prefix", "projects"."remove_source_branch_after_merge", "projects"."marked_for_deletion_at", "projects"."marked_for_deletion_by_user_id", "projects"."autoclose_referenced_issues", "projects"."suggestion_commit_message", "projects"."project_namespace_id", "projects"."hidden", "projects"."organization_id" FROM "projects" WHERE "projects"."id" IN (7, 1, 5, 6, 8, 19, 29, 239, 341, 544, 996) /*application:console,db_config_name:main,line:(pry):1:in `each'*/
  Environment Load (3.2ms)  SELECT "environments".* FROM "environments" WHERE "environments"."id" IN (8, 7, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 2, 1, 10, 9, 21, 22, 23, 24, 25, 26, 27, 28, 30, 231, 332, 333, 334, 335, 336, 337, 338, 339, 340, 341, 342, 343, 344, 345, 346, 347, 348, 349, 350, 351, 352, 353, 354, 355, 356, 357, 358, 359, 360, 361, 362, 363, 364, 365, 366, 367, 368, 369, 370, 371, 372, 373, 374, 375, 376, 377, 378, 379, 380, 381, 382, 383, 384, 385, 386, 387, 388, 389, 390, 391, 392, 393, 394, 395, 396, 397, 398, 399, 400, 401, 402, 403, 404, 405, 406, 407, 408, 409, 410, 411, 412, 413, 414, 415, 416, 417, 418, 419, 420, 421, 422, 423, 424, 425, 426, 427, 428, 429, 532, 533, 534, 535, 536, 537, 538, 539, 540, 541, 542, 543, 544, 545, 546, 547, 548, 549, 550, 551, 552, 553, 554, 555, 556, 557, 558, 559, 560, 561, 562, 563, 564, 565, 566, 567, 568, 569, 570, 571, 572, 573, 574, 575, 576, 577, 578, 579, 580, 581, 582, 583, 584, 585, 586, 587, 588, 589, 590, 591, 592, 593, 594, 595, 596, 597, 598, 599, 600, 601, 602, 603, 604, 605, 606, 607, 608, 609, 610, 611, 612, 613, 614, 615, 616, 617, 618, 619, 620, 621, 622, 623, 624, 625, 626, 627, 628, 629, 630, 631, 977, 978, 979) /*application:console,db_config_name:main,line:(pry):1:in `each'*/

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