Metric spaces are very useful in spatial database, and other applications that deal with it. Especially when want to found object that are similar to other object. This condition does not handle the relative position that found in some tree, such that, RTree, R+-Tree, and R*-Tree. Instead of handling distances between objects, using Euclidean Distance to compute the similarity between them, and retrieve the sets of object from database based on Euclidean distance that make this situation is happen and occurs. This paper proposed methods for similarity search that make the general assumption in the similarity can be done, by focusing on the effectively and efficiency in metric space for spatial database. This paper introduces how to improve the effectively and efficiency of the spatial database. It provided to extract some knowledge from spatial database has been presented. The main goal is to know how the search occurs, by using some assumption and ensures that there is similarity between a given queries Q and a set of object that found in the database.