Improved logic for covering indexes

lib/pghero/methods/suggested_indexes.rb

@@ -34,12 +34,17 @@ def suggested_indexes_by_query(queries: nil, query_stats: nil, indexes: nil)
                 # indexes of same type
                 indexes = existing_columns[index[:using] || "btree"][index[:table]]
 
-                # gist indexes without an opclass
-                # (opclass is part of column name, so columns won't match if opclass present)
-                indexes += existing_columns["gist"][index[:table]]
+                if best_index[:structure][:sort].empty?
+                  # gist indexes without an opclass
+                  # (opclass is part of column name, so columns won't match if opclass present)
+                  indexes += existing_columns["gist"][index[:table]]
 
-                # hash indexes work for equality
-                indexes += existing_columns["hash"][index[:table]] if best_index[:structure][:where].all? { |v| v[:op] == "=" }
+                  # hash indexes work for equality
+                  indexes += existing_columns["hash"][index[:table]] if best_index[:structure][:where].all? { |v| v[:op] == "=" }
+
+                  # brin indexes work for all
+                  indexes += existing_columns["brin"][index[:table]]
+                end
 
                 covering_index = indexes.find { |e| index_covers?(e, index[:columns]) }
                 if covering_index

test/suggested_indexes_test.rb

@@ -14,12 +14,30 @@ def test_basic
     assert_equal [{table: "users", columns: ["email"]}], database.suggested_indexes.map { |q| q.except(:queries, :details) }
   end
 
+  def test_primary_key
+    query = "SELECT * FROM users WHERE id = 1"
+    result = database.suggested_indexes_by_query(queries: [query])[query]
+    assert_equal ["id"], result[:covering_index]
+  end
+
   def test_hash
     query = "SELECT * FROM users WHERE login_attempts = 1"
     result = database.suggested_indexes_by_query(queries: [query])[query]
     assert_equal ["login_attempts"], result[:covering_index]
   end
 
+  def test_hash_multiple_values
+    query = "SELECT * FROM users WHERE login_attempts IN (1, 2)"
+    result = database.suggested_indexes_by_query(queries: [query])[query]
+    assert_equal ["login_attempts"], result[:covering_index]
+  end
+
+  def test_hash_greater_than
+    query = "SELECT * FROM users WHERE login_attempts > 1"
+    result = database.suggested_indexes_by_query(queries: [query])[query]
+    assert_nil result[:covering_index]
+  end
+
   def test_existing_index
     User.where("updated_at > ?", Time.now).to_a
     assert_equal [], database.suggested_indexes.map { |q| q.except(:queries, :details) }
@@ -36,4 +54,28 @@ def test_ltree
     result = database.suggested_indexes_by_query(queries: [query])[query]
     assert_equal ["tree_path"], result[:covering_index]
   end
+
+  def test_range
+    query = "SELECT * FROM users WHERE range = '[0, 0]'"
+    result = database.suggested_indexes_by_query(queries: [query])[query]
+    assert_equal ["range"], result[:covering_index]
+  end
+
+  def test_brin
+    query = "SELECT * FROM users WHERE created_at = NOW()"
+    result = database.suggested_indexes_by_query(queries: [query])[query]
+    assert_equal ["created_at"], result[:covering_index]
+  end
+
+  def test_brin_order
+    query = "SELECT * FROM users ORDER BY created_at LIMIT 1"
+    result = database.suggested_indexes_by_query(queries: [query])[query]
+    assert_nil result[:covering_index]
+  end
+
+  def test_gin
+    query = "SELECT * FROM users WHERE metadata = '{}'::jsonb"
+    result = database.suggested_indexes_by_query(queries: [query])[query]
+    assert_nil result[:covering_index]
+  end
 end

test/support/migrations.rb

@@ -40,11 +40,16 @@
   t.boolean :active
   t.string :country
   t.column :tree_path, :ltree
+  t.column :range, :int4range
+  t.column :metadata, :jsonb
   t.timestamp :created_at
   t.timestamp :updated_at
   t.index :id # duplicate index
   t.index :updated_at
   t.index :login_attempts, using: :hash
   t.index "country gist_trgm_ops", using: :gist
   t.index :tree_path, using: :gist
+  t.index :range, using: :gist
+  t.index :created_at, using: :brin
+  t.index :metadata, using: :gin
 end

test/test_helper.rb

@@ -48,6 +48,8 @@ class User < ActiveRecord::Base
       active: true,
       country: "Test #{rand(30)}",
       tree_path: "path#{rand(30)}",
+      range: (0..rand(5)),
+      metadata: {favorite_color: "red"},
       created_at: Time.now - rand(50).days,
       updated_at: Time.now - rand(50).days
     }