Commit 64315c37 authored by Andreas Brandl's avatar Andreas Brandl
Browse files

Flexible approximate counts with fallback strategies.

parent bf9076535ee7
......@@ -25,21 +25,17 @@ module Count
#
# @param [Array]
# @return [Hash] of Model -> count mapping
def self.approximate_counts(models)
counts_by_model = {}
if Gitlab::Database.postgresql?
#counts_by_model = ReltuplesCountStrategy.new(models).count
counts_by_model = reltuples_from_recently_updated(models)
end
missing_models = models - counts_by_model.keys
ExactCountStrategy.new(missing_models).count.each do |model, count|
counts_by_model[model] = count
def self.approximate_counts(models, strategies = [ReltuplesCountStrategy, ExactCountStrategy])
strategies.each_with_object({}) do |strategy, counts_by_model|
if strategy.enabled?
models_with_missing_counts = models - counts_by_model.keys
counts = strategy.new(models_with_missing_counts).count
counts.each do |model, count|
counts_by_model[model] = count
end
end
end
counts_by_model
end
# Returns a hash of the table names that have recently updated tuples.
......@@ -61,6 +57,10 @@ def count
data[model] = model.count
end
end
def self.enabled?
true
end
end
class ReltuplesCountStrategy
......@@ -92,6 +92,10 @@ def count
{}
end
def self.enabled?
Gitlab::Database.postgresql?
end
private
def table_names
......
......@@ -23,10 +23,14 @@
end
context 'with PostgreSQL', :postgresql do
let(:reltuples_strategy) { double('reltuples_strategy', count: {}) }
before do
allow(Gitlab::Database::Count::ReltuplesCountStrategy).to receive(:new).with(models).and_return(reltuples_strategy)
end
describe 'when reltuples have not been updated' do
it 'counts all models the normal way' do
expect(described_class).to receive(:reltuples_from_recently_updated).with(models).and_return({})
expect(Project).to receive(:count).and_call_original
expect(Identity).to receive(:count).and_call_original
expect(described_class.approximate_counts(models)).to eq({ Project => 3, Identity => 1 })
......@@ -45,7 +49,7 @@
describe 'when some reltuples have been updated' do
it 'counts projects in the fast way' do
expect(described_class).to receive(:reltuples_from_recently_updated).with(models).and_return({ Project => 3 })
expect(reltuples_strategy).to receive(:count).and_return({ Project => 3 })
expect(Project).not_to receive(:count).and_call_original
expect(Identity).to receive(:count).and_call_original
......@@ -53,13 +57,16 @@
end
end
# TODO: This covers two parts: reltuple strategy itself and the fallback
# TODO: Add spec that covers strategy details for reltuple strategy
describe 'when all reltuples have been updated' do
before do
ActiveRecord::Base.connection.execute('ANALYZE projects')
ActiveRecord::Base.connection.execute('ANALYZE identities')
end
#before do
#ActiveRecord::Base.connection.execute('ANALYZE projects')
#ActiveRecord::Base.connection.execute('ANALYZE identities')
#end
it 'counts models with the standard way' do
allow(reltuples_strategy).to receive(:count).and_return({ Project => 3, Identity => 1 })
expect(Project).not_to receive(:count)
expect(Identity).not_to receive(:count)
......
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