diff --git a/changelogs/unreleased/sh-add-uncached-query-limiter.yml b/changelogs/unreleased/sh-add-uncached-query-limiter.yml new file mode 100644 index 00000000000..4318338c229 --- /dev/null +++ b/changelogs/unreleased/sh-add-uncached-query-limiter.yml @@ -0,0 +1,5 @@ +--- +title: Remove N+1 query for author in issues API +merge_request: +author: +type: performance diff --git a/doc/development/query_recorder.md b/doc/development/query_recorder.md index 26d3355e94d..61e5e1afede 100644 --- a/doc/development/query_recorder.md +++ b/doc/development/query_recorder.md @@ -22,6 +22,19 @@ As an example you might create 5 issues in between counts, which would cause the > **Note:** In some cases the query count might change slightly between runs for unrelated reasons. In this case you might need to test `exceed_query_limit(control_count + acceptable_change)`, but this should be avoided if possible. +## Cached queries + +By default, QueryRecorder will ignore cached queries in the count. However, it may be better to count +all queries to avoid introducing an N+1 query that may be masked by the statement cache. To do this, +pass the `skip_cached` variable to `QueryRecorder` and use the `exceed_all_query_limit` matcher: + +it "avoids N+1 database queries" do + control_count = ActiveRecord::QueryRecorder.new(skip_cached: false) { visit_some_page }.count + create_list(:issue, 5) + expect { visit_some_page }.not_to exceed_all_query_limit(control_count) +end +``` + ## Finding the source of the query It may be useful to identify the source of the queries by looking at the call backtrace. diff --git a/lib/api/issues.rb b/lib/api/issues.rb index b64f465ce56..25185d6edc8 100644 --- a/lib/api/issues.rb +++ b/lib/api/issues.rb @@ -16,7 +16,7 @@ module API args[:scope] = args[:scope].underscore if args[:scope] issues = IssuesFinder.new(current_user, args).execute - .preload(:assignees, :labels, :notes, :timelogs, :project) + .preload(:assignees, :labels, :notes, :timelogs, :project, :author) issues.reorder(args[:order_by] => args[:sort]) end diff --git a/spec/requests/api/issues_spec.rb b/spec/requests/api/issues_spec.rb index 4181f4ebbbe..a15d60aafe0 100644 --- a/spec/requests/api/issues_spec.rb +++ b/spec/requests/api/issues_spec.rb @@ -630,15 +630,17 @@ describe API::Issues do end it 'avoids N+1 queries' do - control_count = ActiveRecord::QueryRecorder.new do + get api("/projects/#{project.id}/issues", user) + + control_count = ActiveRecord::QueryRecorder.new(skip_cached: false) do get api("/projects/#{project.id}/issues", user) end.count - create(:issue, author: user, project: project) + create_list(:issue, 3, project: project) expect do get api("/projects/#{project.id}/issues", user) - end.not_to exceed_query_limit(control_count) + end.not_to exceed_all_query_limit(control_count) end it 'returns 404 when project does not exist' do diff --git a/spec/support/helpers/query_recorder.rb b/spec/support/helpers/query_recorder.rb index 28536bbef5e..7ce63375d34 100644 --- a/spec/support/helpers/query_recorder.rb +++ b/spec/support/helpers/query_recorder.rb @@ -1,10 +1,11 @@ module ActiveRecord class QueryRecorder - attr_reader :log, :cached + attr_reader :log, :skip_cached, :cached - def initialize(&block) + def initialize(skip_cached: true, &block) @log = [] @cached = [] + @skip_cached = skip_cached ActiveSupport::Notifications.subscribed(method(:callback), 'sql.active_record', &block) end @@ -16,7 +17,7 @@ module ActiveRecord def callback(name, start, finish, message_id, values) show_backtrace(values) if ENV['QUERY_RECORDER_DEBUG'] - if values[:name]&.include?("CACHE") + if values[:name]&.include?("CACHE") && skip_cached @cached << values[:sql] elsif !values[:name]&.include?("SCHEMA") @log << values[:sql] diff --git a/spec/support/matchers/exceed_query_limit.rb b/spec/support/matchers/exceed_query_limit.rb index 88d22a3ddd9..cd042401f3a 100644 --- a/spec/support/matchers/exceed_query_limit.rb +++ b/spec/support/matchers/exceed_query_limit.rb @@ -1,17 +1,4 @@ -RSpec::Matchers.define :exceed_query_limit do |expected| - supports_block_expectations - - match do |block| - @subject_block = block - actual_count > expected_count + threshold - end - - failure_message_when_negated do |actual| - threshold_message = threshold > 0 ? " (+#{@threshold})" : '' - counts = "#{expected_count}#{threshold_message}" - "Expected a maximum of #{counts} queries, got #{actual_count}:\n\n#{log_message}" - end - +module ExceedQueryLimitHelpers def with_threshold(threshold) @threshold = threshold self @@ -43,7 +30,7 @@ RSpec::Matchers.define :exceed_query_limit do |expected| end def recorder - @recorder ||= ActiveRecord::QueryRecorder.new(&@subject_block) + @recorder ||= ActiveRecord::QueryRecorder.new(skip_cached: skip_cached, &@subject_block) end def count_queries(queries) @@ -61,4 +48,52 @@ RSpec::Matchers.define :exceed_query_limit do |expected| @recorder.log_message end end + + def skip_cached + true + end + + def verify_count(&block) + @subject_block = block + actual_count > expected_count + threshold + end + + def failure_message + threshold_message = threshold > 0 ? " (+#{@threshold})" : '' + counts = "#{expected_count}#{threshold_message}" + "Expected a maximum of #{counts} queries, got #{actual_count}:\n\n#{log_message}" + end +end + +RSpec::Matchers.define :exceed_all_query_limit do |expected| + supports_block_expectations + + include ExceedQueryLimitHelpers + + match do |block| + verify_count(&block) + end + + failure_message_when_negated do |actual| + failure_message + end + + def skip_cached + false + end +end + +# Excludes cached methods from the query count +RSpec::Matchers.define :exceed_query_limit do |expected| + supports_block_expectations + + include ExceedQueryLimitHelpers + + match do |block| + verify_count(&block) + end + + failure_message_when_negated do |actual| + failure_message + end end