1. A method performed by one or more processing devices, comprising: comparing, for each entity of a plurality of entities, a number of connections associated with the entity, in one or more corresponding social graphs, to a threshold number of connections to other entities; based on the comparison, identifying one or more first entities of the plurality of entities that are associated with a number of connections greater than the threshold number of connections to other entities, and in response: identifying first content items in a search index that are authored by the one or more first entities, and associating, for each first content item, a respective author restrict with the first content item, the author restrict comprising data identifying the respective entity that authored the first content item; based on the comparison, identifying one or more second entities of the plurality of entities that are associated with a number of connections less than the threshold number of connections to the other entities, and in response: identifying second content items in the search index that are authored by the one or more second entities, and associating, for each second content item, one or more searcher restricts with the second content item, each searcher restrict of the one or more searcher restricts comprising data that identifies an other entity of a subset of the one or more other entities that are social connected to the second entity that authored the second content item, wherein the first content items are not associated with any searcher restricts; updating the search index to include the respective author restricts associated with each first content item and the respective one or more searcher restricts associated with each second content item; and storing the updated search index in memory.