Only reindex btree and gist indexes

This basically excludes GIN indexes from automatic reindexing. Reason is
that those indexes are slow to build (in particular trigram indexes) and
this would cause problems on GitLab.com.

Relates to https://gitlab.com/gitlab-org/gitlab/-/issues/335211

Changelog: other

db/migrate/20210706152139_add_index_type_to_postgres_indexes_view.rb

+# frozen_string_literal: true
+
+class AddIndexTypeToPostgresIndexesView < ActiveRecord::Migration[6.1]
+  def up
+    execute(<<~SQL)
+      DROP VIEW IF EXISTS postgres_indexes;
+
+      CREATE VIEW postgres_indexes AS
+      SELECT (pg_namespace.nspname::text || '.'::text) || i.relname::text AS identifier,
+        pg_index.indexrelid,
+        pg_namespace.nspname AS schema,
+        i.relname AS name,
+        pg_indexes.tablename,
+        a.amname AS type,
+        pg_index.indisunique AS "unique",
+        pg_index.indisvalid AS valid_index,
+        i.relispartition AS partitioned,
+        pg_index.indisexclusion AS exclusion,
+        pg_index.indexprs IS NOT NULL AS expression,
+        pg_index.indpred IS NOT NULL AS partial,
+        pg_indexes.indexdef AS definition,
+        pg_relation_size(i.oid::regclass) AS ondisk_size_bytes
+      FROM pg_index
+        JOIN pg_class i ON i.oid = pg_index.indexrelid
+        JOIN pg_namespace ON i.relnamespace = pg_namespace.oid
+        JOIN pg_indexes ON i.relname = pg_indexes.indexname
+        LEFT JOIN pg_class t ON t.oid = pg_index.indrelid
+        LEFT JOIN pg_am a ON i.relam = a.oid
+      WHERE pg_namespace.nspname <> 'pg_catalog'::name AND (pg_namespace.nspname = ANY (ARRAY["current_schema"(), 'gitlab_partitions_dynamic'::name, 'gitlab_partitions_static'::name]));
+    SQL
+  end
+
+  def down
+    execute(<<~SQL)
+      DROP VIEW IF EXISTS postgres_indexes;
+
+      CREATE VIEW postgres_indexes AS
+      SELECT (((pg_namespace.nspname)::text || '.'::text) || (pg_class.relname)::text) AS identifier,
+         pg_index.indexrelid,
+         pg_namespace.nspname AS schema,
+         pg_class.relname AS name,
+         pg_indexes.tablename,
+         pg_index.indisunique AS "unique",
+         pg_index.indisvalid AS valid_index,
+         pg_class.relispartition AS partitioned,
+         pg_index.indisexclusion AS exclusion,
+         (pg_index.indexprs IS NOT NULL) AS expression,
+         (pg_index.indpred IS NOT NULL) AS partial,
+         pg_indexes.indexdef AS definition,
+         pg_relation_size((pg_class.oid)::regclass) AS ondisk_size_bytes
+        FROM (((pg_index
+          JOIN pg_class ON ((pg_class.oid = pg_index.indexrelid)))
+          JOIN pg_namespace ON ((pg_class.relnamespace = pg_namespace.oid)))
+          JOIN pg_indexes ON ((pg_class.relname = pg_indexes.indexname)))
+       WHERE ((pg_namespace.nspname <> 'pg_catalog'::name) AND (pg_namespace.nspname = ANY (ARRAY["current_schema"(), 'gitlab_partitions_dynamic'::name, 'gitlab_partitions_static'::name])));
+    SQL
+  end
+end

db/schema_migrations/20210706152139

+45ec2dd6113d112050a1ac062064950fa18b3b5903a9fd60234e9e9fa48c7070
\ No newline at end of file

db/structure.sql

@@ -16583,23 +16583,26 @@ END AS attrelname
   ORDER BY relation_stats.nspname, relation_stats.tblname, relation_stats.idxname;
 
 CREATE VIEW postgres_indexes AS
- SELECT (((pg_namespace.nspname)::text || '.'::text) || (pg_class.relname)::text) AS identifier,
+ SELECT (((pg_namespace.nspname)::text || '.'::text) || (i.relname)::text) AS identifier,
     pg_index.indexrelid,
     pg_namespace.nspname AS schema,
-    pg_class.relname AS name,
+    i.relname AS name,
     pg_indexes.tablename,
+    a.amname AS type,
     pg_index.indisunique AS "unique",
     pg_index.indisvalid AS valid_index,
-    pg_class.relispartition AS partitioned,
+    i.relispartition AS partitioned,
     pg_index.indisexclusion AS exclusion,
     (pg_index.indexprs IS NOT NULL) AS expression,
     (pg_index.indpred IS NOT NULL) AS partial,
     pg_indexes.indexdef AS definition,
-    pg_relation_size((pg_class.oid)::regclass) AS ondisk_size_bytes
-   FROM (((pg_index
-     JOIN pg_class ON ((pg_class.oid = pg_index.indexrelid)))
-     JOIN pg_namespace ON ((pg_class.relnamespace = pg_namespace.oid)))
-     JOIN pg_indexes ON ((pg_class.relname = pg_indexes.indexname)))
+    pg_relation_size((i.oid)::regclass) AS ondisk_size_bytes
+   FROM (((((pg_index
+     JOIN pg_class i ON ((i.oid = pg_index.indexrelid)))
+     JOIN pg_namespace ON ((i.relnamespace = pg_namespace.oid)))
+     JOIN pg_indexes ON ((i.relname = pg_indexes.indexname)))
+     LEFT JOIN pg_class t ON ((t.oid = pg_index.indrelid)))
+     LEFT JOIN pg_am a ON ((i.relam = a.oid)))
   WHERE ((pg_namespace.nspname <> 'pg_catalog'::name) AND (pg_namespace.nspname = ANY (ARRAY["current_schema"(), 'gitlab_partitions_dynamic'::name, 'gitlab_partitions_static'::name])));
 
 CREATE VIEW postgres_partitioned_tables AS

lib/gitlab/database/postgres_index.rb

@@ -7,6 +7,7 @@ module Gitlab
 
       self.table_name = 'postgres_indexes'
       self.primary_key = 'identifier'
+      self.inheritance_column = :_type_disabled
 
       has_one :bloat_estimate, class_name: 'Gitlab::Database::PostgresIndexBloatEstimate', foreign_key: :identifier
       has_many :reindexing_actions, class_name: 'Gitlab::Database::Reindexing::ReindexAction', foreign_key: :index_identifier
@@ -22,10 +23,10 @@ module Gitlab
       # is defined on a table that is not partitioned.
       #
       # Deprecated: Switch to scope .reindexing_support
-      scope :regular, -> { where(unique: false, partitioned: false, exclusion: false, expression: false)}
+      scope :regular, -> { where(unique: false, partitioned: false, exclusion: false, expression: false, type: Gitlab::Database::Reindexing::SUPPORTED_TYPES)}
 
       # Indexes for reindexing with PG12
-      scope :reindexing_support, -> { where(partitioned: false, exclusion: false, expression: false) }
+      scope :reindexing_support, -> { where(partitioned: false, exclusion: false, expression: false, type: Gitlab::Database::Reindexing::SUPPORTED_TYPES) }
 
       scope :not_match, ->(regex) { where("name !~ ?", regex)}
 

lib/gitlab/database/reindexing.rb

@@ -6,6 +6,8 @@ module Gitlab
       # Number of indexes to reindex per invocation
       DEFAULT_INDEXES_PER_INVOCATION = 2
 
+      SUPPORTED_TYPES = %w(btree gist).freeze
+
       # candidate_indexes: Array of Gitlab::Database::PostgresIndex
       def self.perform(candidate_indexes, how_many: DEFAULT_INDEXES_PER_INVOCATION)
         IndexSelection.new(candidate_indexes).take(how_many).each do |index|

spec/lib/gitlab/database/postgres_index_spec.rb

@@ -38,6 +38,12 @@ RSpec.describe Gitlab::Database::PostgresIndex do
     it 'only non-expression indexes' do
       expect(described_class.regular).to all(have_attributes(expression: false))
     end
+
+    it 'only btree and gist indexes' do
+      types = described_class.regular.map(&:type).uniq
+
+      expect(types & %w(btree gist)).to eq(types)
+    end
   end
 
   describe '.reindexing_support' do
@@ -52,6 +58,12 @@ RSpec.describe Gitlab::Database::PostgresIndex do
     it 'only non-expression indexes' do
       expect(described_class.reindexing_support).to all(have_attributes(expression: false))
     end
+
+    it 'only btree and gist indexes' do
+      types = described_class.reindexing_support.map(&:type).uniq
+
+      expect(types & %w(btree gist)).to eq(types)
+    end
   end
 
   describe '.not_match' do