Class: Flydata::SourcePostgresql::QueryBasedSync::ResourceRequester

Inherits:
QueryBasedSync::ResourceRequester show all
Defined in:
lib/flydata/source_postgresql/query_based_sync/resource_requester.rb

Constant Summary collapse

RESPONSE_CLASS = 
Flydata::SourcePostgresql::QueryBasedSync::Response

Instance Attribute Summary

Attributes inherited from QueryBasedSync::ResourceRequester

#context

Instance Method Summary collapse

Methods inherited from QueryBasedSync::ResourceRequester

#each_response, #start

Constructor Details

#initialize(*args) ⇒ ResourceRequester

Returns a new instance of ResourceRequester.



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# File 'lib/flydata/source_postgresql/query_based_sync/resource_requester.rb', line 13

def initialize(*args)
  super
  @tables_missing_meta = []
end

Instance Method Details

#create_resource_client(context) ⇒ Object

Override



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# File 'lib/flydata/source_postgresql/query_based_sync/resource_requester.rb', line 19

def create_resource_client(context)
  FlydataCore::Postgresql::PGClient.new(context.dbconf)
end

#fetch_responses_once(table_name, latest_src_pos) ⇒ Object

Override



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# File 'lib/flydata/source_postgresql/query_based_sync/resource_requester.rb', line 24

def fetch_responses_once(table_name, latest_src_pos)
  table_sym = table_name.to_sym
  t_meta = context.table_meta[table_sym]

  if t_meta.nil? || t_meta.empty?
    unless @tables_missing_meta.include?(table_name)
      @tables_missing_meta << table_name
      log_error "No metadata is available for table '#{table_name}'.  Make sure the table exists and is visible to the PostgreSQL user."
    end
    return
  end

  table_src_pos = context.table_src_pos_files[table_sym].pos
  master_src_pos = context.cur_src_pos_file.pos

  # Set from_sid, to_sid and pk_values

  to_sid = latest_src_pos.snapshot
  pk_values = nil

  # - table.binlog.pos does not exist
  if table_src_pos.nil?
    from_sid = master_src_pos.snapshot
  # - pk_values exists -> continue from the last transaction
  elsif table_src_pos.pk_values
    from_sid = table_src_pos.snapshot
    to_sid = table_src_pos.to_snapshot
    pk_values = table_src_pos.pk_values
  else
    from_sid = table_src_pos.snapshot
  end

  if from_sid == to_sid
    log_debug("Skip fetching records (No changes)")
    return
  end

  log_debug("Start query", from_sid: from_sid, to_sid: to_sid, pk_values: pk_values)

  # Create and execute query
  query = generate_query(t_meta, from_sid, to_sid, pk_values)

  begin
    result = @resource_client.query(query)
  rescue PG::TRSerializationFailure => e
    raise FlydataCore::RetryableError.new(e)
  end

  # Create response object based on result
  responses = build_responses(table_name, result, from_sid: from_sid, to_sid: to_sid, pk_values: pk_values)

  Array(responses)
end