Class: Sequent::Core::Persistors::ReplayOptimizedPostgresPersistor

Inherits:
Object
  • Object
show all
Includes:
Persistor
Defined in:
lib/sequent/core/persistors/replay_optimized_postgres_persistor.rb

Overview

The ReplayOptimizedPostgresPersistor is optimized for bulk loading records in a Postgres database.

Depending on the amount of records it uses CSV import, otherwise statements are batched using normal sql.

Rebuilding the view state (or projection) of an aggregate typically consists of an initial insert and then many updates and maybe a delete. With a normal Persistor (like ActiveRecordPersistor) each action is executed to the database. This persistor creates an in-memory store first and finally flushes the in-memory store to the database. This can significantly reduce the amount of queries to the database. E.g. 1 insert, 6 updates is only a single insert using this Persistor.

After lot of experimenting this turned out to be the fastest way to to bulk inserts in the database. You can tweak the amount of records in the CSV via insert_with_csv_size before it flushes to the database to gain (or loose) speed.

It is highly recommended to create indices on the in memory record_store to speed up the processing. By default all records are indexed by aggregate_id if they have such a property.

Example:

class InvoiceProjector < Sequent::Core::Projector
  on RecipientMovedEvent do |event|
    update_all_records(
      InvoiceRecord,
      { aggregate_id: event.aggregate_id, recipient_id: event.recipient.aggregate_id },
      { recipient_street: event.recipient.street },
    end
  end
end

In this case it is wise to create an index on InvoiceRecord on the aggregate_id and recipient_id attributes like you would in the database. Note that previous versions of this class supported multi-column indexes. These are now split into multiple single-column indexes and the results of each index is combined using set-intersection. This reduces the amount of memory used and makes it possible to use an index in more cases (whenever an indexed attribute is present in the where clause the index will be used, so not all attributes need to be present).

Example:

ReplayOptimizedPostgresPersistor.new(
  50,
  {InvoiceRecord => [:aggregate_id, :recipient_id]}
)

Defined Under Namespace

Modules: InMemoryStruct Classes: Index

Constant Summary collapse

CHUNK_SIZE = 
1024

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(insert_with_csv_size = 50, indices = {}, default_indexed_columns = [:aggregate_id]) ⇒ ReplayOptimizedPostgresPersistor

insert_with_csv_size number of records to insert in a single batch

indices Hash of indices to create in memory. Greatly speeds up the replaying.

Key corresponds to the name of the 'Record'
Values contains list of lists on which columns to index.
E.g. [[:first_index_column], [:another_index, :with_to_columns]]



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# File 'lib/sequent/core/persistors/replay_optimized_postgres_persistor.rb', line 171

def initialize(insert_with_csv_size = 50, indices = {}, default_indexed_columns = [:aggregate_id])
  @insert_with_csv_size = insert_with_csv_size
  @record_store = Hash.new { |h, k| h[k] = Set.new.compare_by_identity }
  @record_index = Hash.new do |h, k|
    h[k] = Index.new(default_indexed_columns.to_set & k.column_names.map(&:to_sym))
  end

  indices.each do |record_class, indexed_columns|
    columns = indexed_columns.flatten(1).to_set(&:to_sym) + default_indexed_columns
    @record_index[record_class] = Index.new(columns & record_class.column_names.map(&:to_sym))
  end

  @record_defaults = Hash.new do |h, record_class|
    h[record_class] = record_class.column_defaults.symbolize_keys
  end
end

Instance Attribute Details

#insert_with_csv_size ⇒ Object

Returns the value of attribute insert_with_csv_size.



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# File 'lib/sequent/core/persistors/replay_optimized_postgres_persistor.rb', line 60

def insert_with_csv_size
  @insert_with_csv_size
end

#record_store ⇒ Object (readonly)

Returns the value of attribute record_store.



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# File 'lib/sequent/core/persistors/replay_optimized_postgres_persistor.rb', line 59

def record_store
  @record_store
end

Instance Method Details

#clear ⇒ Object 



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# File 'lib/sequent/core/persistors/replay_optimized_postgres_persistor.rb', line 358

def clear
  @record_store.clear
  @record_index.each_value(&:clear)
end

#commit ⇒ Object 



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# File 'lib/sequent/core/persistors/replay_optimized_postgres_persistor.rb', line 312

def commit
  @record_store.each do |clazz, records|
    @column_cache ||= {}
    @column_cache[clazz.name] ||= clazz.columns.reduce({}) do |hash, column|
      hash.merge({column.name => column})
    end
    if records.size > @insert_with_csv_size
      csv = CSV.new(StringIO.new)
      column_names = clazz.column_names.reject { |name| name == 'id' }
      records.each do |record|
        csv << column_names.map do |column_name|
          cast_value_to_column_type(clazz, column_name, record)
        end
      end

      conn = Sequent::ApplicationRecord.connection.raw_connection
      copy_data = StringIO.new(csv.string)
      conn.transaction do
        conn.copy_data("COPY #{clazz.table_name} (#{column_names.join(',')}) FROM STDIN WITH csv") do
          while (out = copy_data.read(CHUNK_SIZE))
            conn.put_copy_data(out)
          end
        end
      end
    else
      clazz.unscoped do
        inserts = []
        column_names = clazz.column_names.reject { |name| name == 'id' }
        prepared_values = (1..column_names.size).map { |i| "$#{i}" }.join(',')
        records.each do |record|
          values = column_names.map do |column_name|
            cast_value_to_column_type(clazz, column_name, record)
          end
          inserts << values
        end
        sql = %{insert into #{clazz.table_name} (#{column_names.join(',')}) values (#{prepared_values})}
        inserts.each do |insert|
          clazz.connection.raw_connection.async_exec(sql, insert)
        end
      end
    end
  end
ensure
  clear
end

#create_or_update_record(record_class, values, created_at = Time.now) {|record| ... } ⇒ Object

Yields:

  • (record) 


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# File 'lib/sequent/core/persistors/replay_optimized_postgres_persistor.rb', line 220

def create_or_update_record(record_class, values, created_at = Time.now)
  record = get_record(record_class, values)
  record ||= create_record(record_class, values.merge(created_at: created_at))
  yield record if block_given?
  @record_index[record_class].update(record)
  record
end

#create_record(record_class, values) {|record| ... } ⇒ Object

Yields:

  • (record) 


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# File 'lib/sequent/core/persistors/replay_optimized_postgres_persistor.rb', line 201

def create_record(record_class, values)
  record = struct_cache[record_class].new(**values)
  @record_defaults[record_class].each do |column, default|
    record[column] = default unless values.include? column
  end
  record.updated_at = values[:created_at] if record.respond_to?(:updated_at)

  yield record if block_given?

  @record_store[record_class] << record
  @record_index[record_class].add(record)

  record
end

#create_records(record_class, array_of_value_hashes) ⇒ Object 



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# File 'lib/sequent/core/persistors/replay_optimized_postgres_persistor.rb', line 216

def create_records(record_class, array_of_value_hashes)
  array_of_value_hashes.each { |values| create_record(record_class, values) }
end

#delete_all_records(record_class, where_clause) ⇒ Object 



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# File 'lib/sequent/core/persistors/replay_optimized_postgres_persistor.rb', line 242

def delete_all_records(record_class, where_clause)
  find_records(record_class, where_clause).each do |record|
    delete_record(record_class, record)
  end
end

#delete_record(record_class, record) ⇒ Object 



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# File 'lib/sequent/core/persistors/replay_optimized_postgres_persistor.rb', line 248

def delete_record(record_class, record)
  @record_store[record_class].delete(record)
  @record_index[record_class].remove(record)
end

#do_with_record(record_class, where_clause) {|record| ... } ⇒ Object

Yields:

  • (record) 


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# File 'lib/sequent/core/persistors/replay_optimized_postgres_persistor.rb', line 270

def do_with_record(record_class, where_clause)
  record = get_record!(record_class, where_clause)
  yield record
  @record_index[record_class].update(record)
end

#do_with_records(record_class, where_clause) ⇒ Object 



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# File 'lib/sequent/core/persistors/replay_optimized_postgres_persistor.rb', line 262

def do_with_records(record_class, where_clause)
  records = find_records(record_class, where_clause)
  records.each do |record|
    yield record
    @record_index[record_class].update(record)
  end
end

#find_records(record_class, where_clause) ⇒ Object 



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# File 'lib/sequent/core/persistors/replay_optimized_postgres_persistor.rb', line 276

def find_records(record_class, where_clause)
  where_clause = where_clause.symbolize_keys

  indexed_columns = @record_index[record_class].indexed_columns
  indexed_fields, non_indexed_fields = where_clause.partition { |field, _| indexed_columns.include? field }

  candidate_records = if indexed_fields.present?
                        @record_index[record_class].find(indexed_fields)
                      else
                        @record_store[record_class]
                      end

  return candidate_records.to_a if non_indexed_fields.empty?

  candidate_records.select do |record|
    non_indexed_fields.all? do |k, v|
      expected_value = Persistors.normalize_symbols(v)
      actual_value = Persistors.normalize_symbols(record[k])
      if expected_value.is_a?(Array)
        expected_value.include?(actual_value)
      else
        actual_value == expected_value
      end
    end
  end
end

#get_record(record_class, where_clause) ⇒ Object 



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# File 'lib/sequent/core/persistors/replay_optimized_postgres_persistor.rb', line 237

def get_record(record_class, where_clause)
  results = find_records(record_class, where_clause)
  results.empty? ? nil : results.first
end

#get_record!(record_class, where_clause) ⇒ Object 



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# File 'lib/sequent/core/persistors/replay_optimized_postgres_persistor.rb', line 228

def get_record!(record_class, where_clause)
  record = get_record(record_class, where_clause)
  unless record
    fail("record #{record_class} not found for #{where_clause}, store: #{@record_store[record_class]}")
  end

  record
end

#last_record(record_class, where_clause) ⇒ Object 



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# File 'lib/sequent/core/persistors/replay_optimized_postgres_persistor.rb', line 303

def last_record(record_class, where_clause)
  results = find_records(record_class, where_clause)
  results.empty? ? nil : results.last
end

#prepare ⇒ Object 



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# File 'lib/sequent/core/persistors/replay_optimized_postgres_persistor.rb', line 308

def prepare
  # noop
end

#struct_cache ⇒ Object 



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# File 'lib/sequent/core/persistors/replay_optimized_postgres_persistor.rb', line 82

def struct_cache
  @struct_cache ||= Hash.new do |hash, record_class|
    struct_class = Struct.new(*record_class.column_names.map(&:to_sym), keyword_init: true) do
      include InMemoryStruct
    end
    hash[record_class] = struct_class
  end
end

#update_all_records(record_class, where_clause, updates) ⇒ Object 



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# File 'lib/sequent/core/persistors/replay_optimized_postgres_persistor.rb', line 253

def update_all_records(record_class, where_clause, updates)
  find_records(record_class, where_clause).each do |record|
    updates.each_pair do |k, v|
      record[k] = v
    end
    @record_index[record_class].update(record)
  end
end

#update_record(record_class, event, where_clause = {aggregate_id: event.aggregate_id}, options = {}) {|record| ... } ⇒ Object

Yields:

  • (record) 


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# File 'lib/sequent/core/persistors/replay_optimized_postgres_persistor.rb', line 188

def update_record(record_class, event, where_clause = {aggregate_id: event.aggregate_id}, options = {})
  record = get_record!(record_class, where_clause)
  record.updated_at = event.created_at if record.respond_to?(:updated_at=)
  yield record if block_given?
  @record_index[record_class].update(record)
  update_sequence_number = if options.key?(:update_sequence_number)
                             options[:update_sequence_number]
                           else
                             record.respond_to?(:sequence_number=)
                           end
  record.sequence_number = event.sequence_number if update_sequence_number
end