| 摘要 |
<p>A multiple memory system continuously available for queries. Multiple copies of a data set allow that data set to be available for inquiries at all times and specifically at those times when the data set is being updated. At least one copy of the data set is always available in read mode even while another copy might be in the process of being updated. The data set being queried is always either the most current data or very close to being most current. The maximum latency is a function of the amount of information in the most recent update. The implementation of this type of system is especially advantageous for search engines for which queries must be responded to in a very prompt manner. In this type of system it is not acceptable for an inquiry to be delayed while an update is taking place, and it is acceptable for an inquiry to take place on data which is almost completely current if not completely current.</p> |
