Remove unused indexes

These indexes were originally added because it was assumed that
verification backfill queries would be the same for the new Geo
Self-Service Framework as they were for legacy project/wiki
verification. But we have added a state machine and are using a
different approach for the framework, so the queries are different, and
will not use these indexes.

changelogs/unreleased/mk-remove-unused-indexes.yml

+---
+title: 'Geo: Remove unused indexes'
+merge_request: 48504
+author:
+type: changed

db/post_migrate/20201124185639_remove_unused_indexes.rb

+# frozen_string_literal: true
+
+class RemoveUnusedIndexes < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    remove_concurrent_index_by_name :packages_package_files, "packages_packages_verification_failure_partial"
+    remove_concurrent_index_by_name :packages_package_files, "packages_packages_verification_checksum_partial"
+    remove_concurrent_index_by_name :snippet_repositories, 'snippet_repositories_verification_failure_partial'
+    remove_concurrent_index_by_name :snippet_repositories, 'snippet_repositories_verification_checksum_partial'
+    remove_concurrent_index_by_name :terraform_state_versions, 'terraform_state_versions_verification_failure_partial'
+    remove_concurrent_index_by_name :terraform_state_versions, 'terraform_state_versions_verification_checksum_partial'
+  end
+
+  def down
+    add_concurrent_index :packages_package_files, :verification_failure, where: "(verification_failure IS NOT NULL)", name: "packages_packages_verification_failure_partial"
+    add_concurrent_index :packages_package_files, :verification_checksum, where: "(verification_checksum IS NOT NULL)", name: "packages_packages_verification_checksum_partial"
+    add_concurrent_index :snippet_repositories, :verification_failure, where: "(verification_failure IS NOT NULL)", name: 'snippet_repositories_verification_failure_partial'
+    add_concurrent_index :snippet_repositories, :verification_checksum, where: "(verification_checksum IS NOT NULL)", name: 'snippet_repositories_verification_checksum_partial'
+    add_concurrent_index :terraform_state_versions, :verification_failure, where: "(verification_failure IS NOT NULL)", name: 'terraform_state_versions_verification_failure_partial'
+    add_concurrent_index :terraform_state_versions, :verification_checksum, where: "(verification_checksum IS NOT NULL)", name: 'terraform_state_versions_verification_checksum_partial'
+  end
+end

db/schema_migrations/20201124185639

+dd36b2815c62ef9710d88fa92c410398a228c50a7e51d44ce02e85c9f63d648e
\ No newline at end of file

db/structure.sql

@@ -22507,20 +22507,12 @@ CREATE UNIQUE INDEX one_canonical_wiki_page_slug_per_metadata ON wiki_page_slugs
 
 CREATE INDEX package_name_index ON packages_packages USING btree (name);
 
-CREATE INDEX packages_packages_verification_checksum_partial ON packages_package_files USING btree (verification_checksum) WHERE (verification_checksum IS NOT NULL);
-
-CREATE INDEX packages_packages_verification_failure_partial ON packages_package_files USING btree (verification_failure) WHERE (verification_failure IS NOT NULL);
-
 CREATE INDEX partial_index_ci_builds_on_scheduled_at_with_scheduled_jobs ON ci_builds USING btree (scheduled_at) WHERE ((scheduled_at IS NOT NULL) AND ((type)::text = 'Ci::Build'::text) AND ((status)::text = 'scheduled'::text));
 
 CREATE INDEX partial_index_deployments_for_legacy_successful_deployments ON deployments USING btree (id) WHERE ((finished_at IS NULL) AND (status = 2));
 
 CREATE INDEX partial_index_deployments_for_project_id_and_tag ON deployments USING btree (project_id) WHERE (tag IS TRUE);
 
-CREATE INDEX snippet_repositories_verification_checksum_partial ON snippet_repositories USING btree (verification_checksum) WHERE (verification_checksum IS NOT NULL);
-
-CREATE INDEX snippet_repositories_verification_failure_partial ON snippet_repositories USING btree (verification_failure) WHERE (verification_failure IS NOT NULL);
-
 CREATE UNIQUE INDEX snippet_user_mentions_on_snippet_id_and_note_id_index ON snippet_user_mentions USING btree (snippet_id, note_id);
 
 CREATE UNIQUE INDEX snippet_user_mentions_on_snippet_id_index ON snippet_user_mentions USING btree (snippet_id) WHERE (note_id IS NULL);
@@ -22531,10 +22523,6 @@ CREATE INDEX temporary_index_vulnerabilities_on_id ON vulnerabilities USING btre
 
 CREATE UNIQUE INDEX term_agreements_unique_index ON term_agreements USING btree (user_id, term_id);
 
-CREATE INDEX terraform_state_versions_verification_checksum_partial ON terraform_state_versions USING btree (verification_checksum) WHERE (verification_checksum IS NOT NULL);
-
-CREATE INDEX terraform_state_versions_verification_failure_partial ON terraform_state_versions USING btree (verification_failure) WHERE (verification_failure IS NOT NULL);
-
 CREATE INDEX tmp_build_stage_position_index ON ci_builds USING btree (stage_id, stage_idx) WHERE (stage_idx IS NOT NULL);
 
 CREATE INDEX tmp_idx_blocked_by_type_links ON issue_links USING btree (target_id) WHERE (link_type = 2);