1. A computer implemented method for scheduling an index merge, said method comprising: determining a total query cost indicative of individually consulting each index in a set of indexes, wherein determining the total query cost comprises determining a historic query cost associated with querying a first index prior to the first index being merged into an ancestral index, and adding the historic query cost of the first index to estimated query costs for a plurality of other indexes in the set of indexes; determining a total merge cost indicative of merging said set of indexes into a single merged index, wherein determining the total merge cost comprises determining a historic merge cost associated with merging the first index into the ancestral index, and adding the historic merge cost of the first index to estimated merge costs for the plurality of other indexes in the set of indexes; comparing said total merge cost with said total query cost; and depending upon a result of said comparison, performing one of: a) merging said set of indexes into a merged index and maintaining said merge cost, or b) individually consulting each index in said set.