A full-text search index system and method is generated by creating instances of a database index from an in-memory inverted list of keywords associated with a text identifier and the occurrences of the keyword in the text. Instances of the index are placed in a priority queue. A merge scheduling process determines when a merge should be initiated, selects instances of the index to be merged and selects a type of merge to perform. Instances of an index are assigned a temporal indicator (timestamp). A set of instances is selected to be merged. The set of instances is validated and merged.