System, method and program for information processing

An information processing method comprising:

• storing a plurality of indexes, the plurality of indexes comprising a first index and a plurality of second indexes corresponding to versions of the first index;
• and
• providing by a hardware processor, in response to a received search query, a first document from among the one or more documents based on the first index;
• and wherein:
• the first index includes access control information and stores on a per-group basis, a list of one or more documents accessible by each group of a plurality of groups of users.

A non-transitory computer-readable recording medium storing a program that enables a computer to execute an information processing method, the method comprising:

• storing a plurality of indexes, the plurality of indexes comprising a first index and a plurality of second indexes corresponding to versions of the first index;
• providing by a hardware processor, in response to a received search query, a first document from among the one or more documents based on the first index;
• and wherein:
• the first index includes access control information and stores on a per-group basis a list of one or more documents accessible by each group of a plurality of groups of users.