1. A method comprising: receiving a target image for inclusion in a database with a search tree; predicting a querying performance for the target image if the target image were included in the search tree of the database, wherein the search tree has a fixed tree structure that does not change when adding new target images; and selecting one of inclusion of the target image in the search tree of the database and rejection of the target image from the search tree of the database based on the querying performance, wherein the fixed tree structure of the search tree does not change if the inclusion of the target image is selected.