Apparatus and method for indexing electronic content

A non-transitory computer-readable medium storing instructions that, when executed by a processor, cause the processor to perform a method of operating a content index, the method comprising:

• indexing multiple content collections in a computer system memory, wherein each content collection is indexed by storing in the index a corresponding entry comprising:
• one or more property tokens, each property token representing a property of the corresponding content collection;
• and
• one or more attribute tokens, each attribute token representing an attribute of a target audience of the corresponding content collection and a corresponding value of the attribute;
• maintaining the index by:
• for each entry that receives multiple modifications after it is written and before it is re-written, collapsing the multiple modifications to a single modification that is applied to the entry when the entry is re-written;
• receiving a request for content to be served to a target user, the request comprising:
• a set of properties of content collections from which content is to be selected to serve to the target user;
• and
• a set of attributes of the target user and corresponding values;
• searching the index for entries that match the request;
• and
• in response to the request for content, communicating identities of one or more content collections that satisfy the request.

A non-transitory computer-readable medium containing a data structure for indexing electronic content items for serving in response to content requests, the data structure comprising:

• multiple independent slices, each slice comprising:
• metadata for:
• identifying the slice;
• and
• controlling access to the slice;
• and
• multiple entries, each entry corresponding to at least one item of electronic content and comprising:
• metadata relating to the corresponding at least one item;
• one or more property tokens, each property token representing a property of the at least one item;
• and
• multiple attribute tokens, each attribute token representing an attribute of a target audience of the at least one item of electronic content and a value of that attribute.

A system for operating a content index, the system comprising:

• a memory comprising:
• an index of electronic content, wherein each entry in the index corresponds to a set of electronic content and comprises:
• a set of property tokens representing properties of the set of electronic content;
• and
• a set of attribute tokens representing attributes of a target audience of the set of electronic content and corresponding values of the attributes;
• and
• at least one queue for storing modifications to the index;
• wherein the index comprises multiple independent slices, each slice comprising multiple index entries;
• maintenance logic for periodically modifying the index, wherein each periodic modification of the index includes collapsing multiple modifications to a single index entry to a single modification prior to application of the single modification;
• and
• reader logic for searching the index, in response to a request for content, for entries having target audiences matching a target user to whom the requested content is to be presented.