Abstract: Methods, including computer programs encoded on a computer storage medium, for improving database functionality. In one aspect, a method includes: in response to receiving a query for data associated with one or more properties, accessing listing information for multiple, different communities within which multiple, different types of properties are physically located; selecting, from among the different communities, a particular set of communities; determining that a value of one or more properties within the selected particular set of communities is missing or stale; obtaining an initial estimate of the value of one or more properties within the particular set of communities; defining a cost function that depends on a set of parameters, optimizing the cost function to generate a set of optimal parameters, and obtaining an updated estimate of the value of each property within the particular set of communities based on the generated set of optimal parameters.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer readable storage medium, for identifying entities based on value. In one aspect, the method may include actions for receiving a query that specifies a location. Additional actions may include identifying candidate entities that are identified as responsive to the query and that are associated with the location, selecting a subset of the candidate entities, and determining a representative value of an attribute that is associated with each candidate entity of the subset of the candidate entities. Other actions may include in response to determining that the current value of the attribute that is associated with the particular candidate entity of the subset deviates more than a threshold amount from the representative value, adjusting a ranking score for the particular candidate entity, and ranking the particular candidate based at least on the ranking score for the particular candidate entity.

Abstract: Methods, systems, and apparatus, including computer programs encoded on a computer readable storage medium, for identifying entities based on value. In one aspect, the method may include actions for receiving a query that specifies a location. Additional actions may include identifying candidate entities that are identified as responsive to the query and that are associated with the location, selecting a subset of the candidate entities, and determining a representative value of an attribute that is associated with each candidate entity of the subset of the candidate entities. Other actions may include in response to determining that the current value of the attribute that is associated with the particular candidate entity of the subset deviates more than a threshold amount from the representative value, adjusting a ranking score for the particular candidate entity, and ranking the particular candidate based at least on the ranking score for the particular candidate entity.