# File activerecord/lib/active_record/connection_adapters/sqlite3/database_statements.rb, line 79
def begin_isolated_db_transaction(isolation) #:nodoc
  raise TransactionIsolationError, "SQLite3 only supports the `read_uncommitted` transaction isolation level" if isolation != :read_uncommitted
  raise StandardError, "You need to enable the shared-cache mode in SQLite mode before attempting to change the transaction isolation level" unless shared_cache?

  Thread.current.thread_variable_set("read_uncommitted", @connection.get_first_value("PRAGMA read_uncommitted"))
  @connection.read_uncommitted = true
  begin_db_transaction
end

# File activerecord/lib/active_record/connection_adapters/sqlite3/database_statements.rb, line 73
def exec_delete(sql, name = "SQL", binds = [])
  exec_query(sql, name, binds)
  @connection.changes
end

# File activerecord/lib/active_record/connection_adapters/sqlite3/database_statements.rb, line 36
def exec_query(sql, name = nil, binds = [], prepare: false)
  if preventing_writes? && write_query?(sql)
    raise ActiveRecord::ReadOnlyError, "Write query attempted while in readonly mode: #{sql}"
  end

  materialize_transactions
  mark_transaction_written_if_write(sql)

  type_casted_binds = type_casted_binds(binds)

  log(sql, name, binds, type_casted_binds) do
    ActiveSupport::Dependencies.interlock.permit_concurrent_loads do
      # Don't cache statements if they are not prepared
      unless prepare
        stmt = @connection.prepare(sql)
        begin
          cols = stmt.columns
          unless without_prepared_statement?(binds)
            stmt.bind_params(type_casted_binds)
          end
          records = stmt.to_a
        ensure
          stmt.close
        end
      else
        stmt = @statements[sql] ||= @connection.prepare(sql)
        cols = stmt.columns
        stmt.reset!
        stmt.bind_params(type_casted_binds)
        records = stmt.to_a
      end

      build_result(columns: cols, rows: records)
    end
  end
end

# File activerecord/lib/active_record/connection_adapters/sqlite3/database_statements.rb, line 16
def explain(arel, binds = [])
  sql = "EXPLAIN QUERY PLAN #{to_sql(arel, binds)}"
  SQLite3::ExplainPrettyPrinter.new.pp(exec_query(sql, "EXPLAIN", []))
end