1. A method comprising: at a respective server system having one or more processors and memory storing one or more programs that when executed by the one or more processors cause the respective server system to perform the method, the method comprising: receiving, from a requestor, a select distinct query for retrieving information corresponding to distinct value combinations of one or more properties for entities satisfying requestor-specified filter criteria; in response to the query: identifying a set of index portions including two or more index portions in accordance with the requestor-specified filter criteria, wherein index entries in each respective index portion in the set of index portions are sorted in a predefined sort order in accordance with value combinations of the one or more properties; identifying one or more distinct value combinations of the one or more properties for entities satisfying the requestor-specified filter criteria, wherein the identifying includes: obtaining an initial value of a query cursor as a current value of the query cursor, wherein the initial value of the query cursor indicates locations in each of the two or more index portions corresponding to a first value of the one or more properties; retrieving two or more candidate value combinations, including, for each respective index portion in the set of index portions, retrieving a respective candidate value combination of the one or more properties at an index location that is equal or sequentially adjacent, in the respective index portion, to the current value of the query cursor; comparing the respective candidate value combinations so as to identify distinct value combinations, if any, from the plurality of respective candidate value combinations in accordance with the query; and; updating the current value of the query cursor based on one of the retrieved candidate value combinations and repeating the retrieving candidate value combinations and the comparing candidate value combinations one or more times for the set of index portions until a termination condition has been met; and transmitting information corresponding to the identified one or more distinct value combinations to the requestor.
1. A method comprising: at a respective server system having one or more processors and memory storing one or more programs that when executed by the one or more processors cause the respective server system to perform the method, the method comprising: receiving, from a requestor, a select distinct query for retrieving information corresponding to distinct value combinations of one or more properties for entities satisfying requestor-specified filter criteria; in response to the query: identifying a set of index portions including two or more index portions in accordance with the requestor-specified filter criteria, wherein index entries in each respective index portion in the set of index portions are sorted in a predefined sort order in accordance with value combinations of the one or more properties; identifying one or more distinct value combinations of the one or more properties for entities satisfying the requestor-specified filter criteria, wherein the identifying includes: obtaining an initial value of a query cursor as a current value of the query cursor, wherein the initial value of the query cursor indicates locations in each of the two or more index portions corresponding to a first value of the one or more properties; retrieving two or more candidate value combinations, including, for each respective index portion in the set of index portions, retrieving a respective candidate value combination of the one or more properties at an index location that is equal or sequentially adjacent, in the respective index portion, to the current value of the query cursor; comparing the respective candidate value combinations so as to identify distinct value combinations, if any, from the plurality of respective candidate value combinations in accordance with the query; and; updating the current value of the query cursor based on one of the retrieved candidate value combinations and repeating the retrieving candidate value combinations and the comparing candidate value combinations one or more times for the set of index portions until a termination condition has been met; and transmitting information corresponding to the identified one or more distinct value combinations to the requestor. 14. The method of claim 1 , wherein: the set of index portions includes a first index portion and a second index portion; the retrieving candidate value combinations includes: retrieving, from the first index portion, a first batch of value combinations, wherein the first batch includes a plurality of consecutive value combinations from the first index portion; identifying a first set of one or more candidate value combinations from the first batch of value combinations; retrieving, from the second index portion, a second batch of value combinations, wherein the second batch includes a plurality of consecutive value combinations from the second index portion; and identifying a second set of one or more candidate value combinations from the second batch of value combinations; and the comparing candidate value combinations includes comparing one or more candidate value combinations from the first set of candidate value combinations with one or more candidate value combinations from the second set of candidate value combinations in accordance with the query.