The embodiments provide systems and methods for efficiently and accurately differentiating requests directed to uncacheable content from requests directed to cacheable content based on identifiers from the requests. The differentiation occurs without analysis or retrieval of the content being requested. Some embodiments hash identifiers of prior requests that resulted in uncacheable content being served in order to set indices within a bloom filter. The bloom filter then tracks prior uncacheable requests without storing each of the identifiers so that subsequent requests for uncacheable requests can be easily identified based on a hash of the request identifier and set indices of the bloom filter. Some embodiments produce a predictive model identifying uncacheable content requests by tracking various characteristics found in identifiers of prior requests that resulted in uncacheable content being served. Subsequent requests with identifiers having similar characteristics to those of the predictive model can then be differentiated.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. A method comprising: receiving a plurality of requests at a request distribution server; extracting an identifier from each request of the plurality of requests at the request distribution server; detecting based on the identifier of each request, a first set of the plurality of requests directed to cacheable content and a different second set of the plurality of requests directed to uncacheable content, wherein said detecting is performed without inspecting or obtaining requested content, wherein cacheable content comprises common content that is presented to a plurality of different users, and wherein uncacheable content comprises content that is unique in some form for each user of a plurality of different users; distributing the first set of requests from the request distribution device across a set of servers according to a first request distribution scheme; and distributing the second set of requests from the request distribution device across the set of servers according to a different second request distribution scheme. 2. The method of claim 1, wherein distributing the first set of requests comprises performing a persistent distribution with requests directed to same content being passed to a same server of the set of servers, and wherein distributing the second set of requests comprises performing a round-robin distribution of the second set of requests across the set of servers. 3. The method of claim 1 further comprising producing a bloom filter index from hashing the identifier of each request from the plurality of requests. 4. The method of claim 3, wherein said detecting comprises identifying a particular request from the plurality of requests as an uncacheable content request based on the bloom filter index produced from hashing the identifier of the particular request mapping to a set index within a bloom filter and identifying the particular request as a cacheable content request based on the bloom filter index mapping to an index within the bloom filter that is not set. 5. The method of claim 1 further comprising identifying a first common characteristic within at least a subset of the first set of requests and a second common characteristic within at least a subset of the second set of requests. 6. The method of claim 5, wherein said detecting comprises identifying a particular request from the plurality of requests as a cacheable content request based on the particular request identifier comprising the first common characteristic and identifying the particular request as an uncacheable content request based on the particular request identifier comprising the second common characteristic. 7. The method of claim 1, wherein distributing the first set of requests comprises restricting distribution of the first set of requests across a first subset of the set of servers based on the first request distribution scheme creating a first routing domain within the set of servers, and wherein distributing the second set of requests comprises restricting distribution of the second set of requests across a second subset of the set of servers based on the second request distribution scheme creating a different second routing domain within the set of servers. 8. The method of claim 7, wherein the first subset of servers is optimized for cacheable content as a result of each server of the first subset of servers comprising a large storage cache, and wherein the second subset of servers is optimized uncacheable content as a result of each server of the second subset of servers comprising a small storage cache. 9. A method comprising: tracking each request of a first set of requests to a different index of a first plurality of indices at a request distribution server, wherein each request of the first set of requests comprises an identifier requesting cacheable content, wherein cacheable content is common content that is served to two or more users; tracking each request of a different second set of requests to a different index of a second plurality of indices at a request distribution server, wherein each request of the second set of requests comprises an identifier requesting uncacheable content, wherein uncacheable content is content that is customized for each requesting user; receiving a request at the request distribution server; selecting a particular index from each of the first and second plurality of indices from hashing an identifier of said request; routing the request from the request distribution server to a first server from a plurality of content delivery servers in response to the particular index having a set value in the first plurality of indices; and routing the request from the request distribution server to a different second server from the plurality of content delivery servers in response to the particular index having a set value in the second plurality of indices. 10. The method of claim 9, wherein routing the request to the first server comprises selecting the first server according to a first distribution scheme, and wherein routing the request to the second server comprises selecting the second server according to a different second distribution scheme. 11. The method of claim 9 further comprising monitoring content passed in response to said request from either the first or second server. 12. The method of claim 11 further comprising setting the particular index in the first plurality of indices based on said monitoring identifying cacheable content being served in response to said request, and setting the particular index in the second plurality of indices based on said monitoring identifying uncacheable content being served in response to said request. 13. The method of claim 9, wherein the first plurality of indices form a first bloom filter tracking cacheable content requests previously received by the request distribution server and the second plurality of indices form a second bloom filter tracking uncacheable content requests previously received by the request distribution server. 14. The method of claim 9 further comprising selecting from the plurality of content delivery servers, a cacheable content optimized server in response to the particular index having a set value in the first plurality of indices, wherein the cacheable content optimized server comprises a large storage cache, and wherein the cacheable content optimized server is the first server. 15. The method of claim 14 further comprising selecting from the plurality of content delivery servers, an uncacheable content optimized server in response to the particular index having a set value in the second plurality of indices, wherein the uncacheable content optimized server comprises a server with low overall load or a small storage cache, and wherein the uncacheable content optimized server is the second server. 16. A method comprising: monitoring at a request distribution, different cacheable content returned from a plurality of content delivery servers in response to a first set of requests and different uncacheable content returned from the plurality of content delivery servers in response to a second set of requests; producing at a request distribution server, a first predictive model based on a first set of common characteristics found in Uniform Resource Locators (URLs) of the first set of requests and a second predictive model based on a different second set of common characteristics found in URLs of the second set of requests, wherein the first and second sets of common characteristics comprise one or more of a common URL domain, URL path, URL filename, URL file extension, and URL query string parameter found in two or more requests; receiving a particular request at the request distribution server; predictively routing the particular request as a cacheable content request based on the particular request comprising a URL having at least one characteristic in common with the first set of common characteristics of the first predictive model, wherein predictively routing the particular request as a cacheable content request comprises routing the request from the request distribution server across the plurality of content delivery servers according to a first distribution scheme; and predictively routing the particular request as an uncacheable content request based on the particular request comprising a URL having at least one characteristic in common with the second set of common characteristics of the second predictive model, wherein predictively routing the particular request as an uncacheable content request comprises routing the request from the request distribution server across the plurality of content delivery servers according to a different second distribution scheme. 17. The method of claim 16, wherein producing the first predictive model comprises tracking a frequency with which a plurality of characteristics appear in the URLs of the first set of requests and wherein producing the second predictive model comprises tracking a frequency with which the plurality of characteristics appear in the URLs of the second set of requests. 18. The method of claim 17, wherein predictively routing the particular request as a cacheable content request comprises determining that the particular request URL comprises at least one characteristic appearing with a high probability in identifiers of the first set of identifiers than in identifiers of second set of identifiers. 19. The method of claim 16 further comprising extracting a URL and temporarily storing the URL from each request of the first and second sets of requests prior to said monitoring. 20. The method of claim 20, wherein said producing the first predictive model comprises retrieving the URLs temporarily stored for the first set of requests and analyzing the URLs of the first set of requests for said first set common characteristics.