Class: Exwiw::ExplainRunner

Inherits:
Object
  • Object
show all
Defined in:
lib/exwiw/explain_runner.rb

Instance Method Summary collapse

Constructor Details

#initialize(connection_config:, schema_dir:, dump_target:, logger:, io: $stdout, explain_verbosity: nil) ⇒ ExplainRunner

Returns a new instance of ExplainRunner.



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# File 'lib/exwiw/explain_runner.rb', line 5

def initialize(
  connection_config:,
  schema_dir:,
  dump_target:,
  logger:,
  io: $stdout,
  explain_verbosity: nil
)
  @connection_config = connection_config
  @schema_dir = schema_dir
  @dump_target = dump_target
  @logger = logger
  @io = io
  # mongodb-only; nil lets the adapter pick its safe default (queryPlanner).
  @explain_verbosity = explain_verbosity
end

Instance Method Details

#run ⇒ Object 



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# File 'lib/exwiw/explain_runner.rb', line 22

def run
  adapter = Adapter.build(@connection_config, @logger)
  # explain executes nothing, so an adapter whose non-target scope is captured
  # at runtime (mongodb) has no parent ids to filter children by; ask it to
  # build placeholder scope filters so each query reflects the real dump.
  adapter.explain_scope_with_placeholders!
  configs = load_table_config(adapter.class.table_config_class)
  validate_ignored(configs)

  table_by_name = configs.each_with_object({}) { |config, hash| hash[config.name] = config }

  target = table_by_name[@dump_target.table_name]
  validate_target_exists!(target)
  adapter.validate_as_dump_target!(target) if target

  dumpable_configs = configs.select { |c| adapter.dumpable?(c) }
  QueryAstBuilder.validate_scope!(dumpable_configs, table_by_name, @dump_target, @logger)

  @logger.debug("Determining table processing order...")
  ordered_table_names = DetermineTableProcessingOrder.run(dumpable_configs, logger: @logger)

  total_size = ordered_table_names.size
  ordered_table_names.each_with_index do |table_name, idx|
    table = table_by_name.fetch(table_name)
    if table.ignore
      @logger.debug("Skipping explain for '#{table_name}' (ignore:true)")
      next
    end

    @logger.debug("Explaining '#{table_name}'... (#{idx + 1}/#{total_size})")

    query_ast = adapter.build_query(table, @dump_target, table_by_name)
    # describe_query is the adapter-agnostic "what query is this": the
    # commented SELECT for SQL adapters, the find description for mongodb.
    query_text = adapter.describe_query(query_ast)
    explain_text = adapter.explain(query_ast, verbosity: @explain_verbosity)

    @io.puts "-- [#{idx + 1}/#{total_size}] #{table_name}"
    @io.puts query_text
    @io.puts
    @io.puts "-- EXPLAIN:"
    @io.puts explain_text
    @io.puts
  end
end