# File activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb, line 211
def begin_db_transaction
  execute "BEGIN"
end

# File activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb, line 215
def begin_isolated_db_transaction(isolation)
  begin_db_transaction
  execute "SET TRANSACTION ISOLATION LEVEL #{transaction_isolation_levels.fetch(isolation)}"
end

# File activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb, line 221
def commit_db_transaction
  execute "COMMIT"
end

# File activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb, line 93
def create
  super.insert
end

# File activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb, line 172
def exec_delete(sql, name = 'SQL', binds = [])
  execute_and_clear(sql, name, binds) {|result| result.cmd_tuples }
end

# File activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb, line 191
def exec_insert(sql, name, binds, pk = nil, sequence_name = nil)
  val = exec_query(sql, name, binds)
  if !use_insert_returning? && pk
    unless sequence_name
      table_ref = extract_table_ref_from_insert_sql(sql)
      sequence_name = default_sequence_name(table_ref, pk)
      return val unless sequence_name
    end
    last_insert_id_result(sequence_name)
  else
    val
  end
end

# File activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb, line 159
def exec_query(sql, name = 'SQL', binds = [])
  execute_and_clear(sql, name, binds) do |result|
    types = {}
    fields = result.fields
    fields.each_with_index do |fname, i|
      ftype = result.ftype i
      fmod  = result.fmod i
      types[fname] = get_oid_type(ftype, fmod, fname)
    end
    ActiveRecord::Result.new(fields, result.values, types)
  end
end

# File activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb, line 226
def exec_rollback_db_transaction
  execute "ROLLBACK"
end

# File activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb, line 153
def execute(sql, name = nil)
  log(sql, name) do
    @connection.async_exec(sql)
  end
end

# File activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb, line 5
def explain(arel, binds = [])
  sql = "EXPLAIN #{to_sql(arel, binds)}"
  ExplainPrettyPrinter.new.pp(exec_query(sql, 'EXPLAIN', binds))
end

# File activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb, line 76
def insert_sql(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil)
  unless pk
    # Extract the table from the insert sql. Yuck.
    table_ref = extract_table_ref_from_insert_sql(sql)
    pk = primary_key(table_ref) if table_ref
  end

  if pk && use_insert_returning?
    select_value("#{sql} RETURNING #{quote_column_name(pk)}")
  elsif pk
    super
    last_insert_id_value(sequence_name || default_sequence_name(table_ref, pk))
  else
    super
  end
end

# File activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb, line 69
def select_rows(sql, name = nil, binds = [])
  execute_and_clear(sql, name, binds) do |result|
    result.values
  end
end

# File activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb, line 47
def select_value(arel, name = nil, binds = [])
  arel, binds = binds_from_relation arel, binds
  sql = to_sql(arel, binds)
  execute_and_clear(sql, name, binds) do |result|
    result.getvalue(0, 0) if result.ntuples > 0 && result.nfields > 0
  end
end

# File activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb, line 55
def select_values(arel, name = nil)
  arel, binds = binds_from_relation arel, []
  sql = to_sql(arel, binds)
  execute_and_clear(sql, name, binds) do |result|
    if result.nfields > 0
      result.column_values(0)
    else
      []
    end
  end
end

# File activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb, line 177
def sql_for_insert(sql, pk, id_value, sequence_name, binds)
  unless pk
    # Extract the table from the insert sql. Yuck.
    table_ref = extract_table_ref_from_insert_sql(sql)
    pk = primary_key(table_ref) if table_ref
  end

  if pk && use_insert_returning?
    sql = "#{sql} RETURNING #{quote_column_name(pk)}"
  end

  [sql, binds]
end

# File activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb, line 206
def update_sql(sql, name = nil)
  super.cmd_tuples
end