13. A search system comprising: a storage system including a plurality of storage devices, the storage system storing a knowledge base, a plurality of index clusters, and a plurality of records; and a processing system including one or more processors that execute computer readable instructions, the computer readable instructions, when executed by the processing system, causing the processing system to: receive a search query containing one or more query terms from a remote device; determine one or more entity types implicated by the search query based on the one or more query terms and the knowledge base, and for each entity type, determining an entity score indicating a likelihood that the search query implicates the entity type based on the knowledge base; identify one or more index clusters from the plurality of index clusters to search based on the one or more entity types implicated by the search query, each index cluster having a plurality of tiers, and each tier including one or more search indexes; generate a query execution plan based on the entity scores of the one or more entity types, the query execution plan indicating, for each identified index cluster, i) a priority assigned to a search of the index cluster and ii) a time constraint assigned to the indicating cluster indicating a maximum amount of time allotted to search the index cluster; perform a consumer driven search on the identified index clusters based on a set of query terms corresponding to the one or more query terms and in accordance with the query execution plan to identify a delivery consideration set of records; generate delivery search results based on the delivery consideration set of records based on the one or more of the plurality of records; transmit the delivery search results to the remote device; and perform a continuation search by, for each index cluster indicated in the query execution plan: assigning a lowest priority and an unlimited time constraint to the set of query terms with respect to the index cluster; inserting the set of query terms in a queue corresponding to the index cluster with other intent queries, each other intent query having a respective priority assigned thereto: searching all tiers of the index cluster using the set of query terms; and updating a continuation consideration set of records based on the searching, wherein the continuation consideration set of records indicates records identified across all of the index clusters indicated in the query execution plan.
13. A search system comprising: a storage system including a plurality of storage devices, the storage system storing a knowledge base, a plurality of index clusters, and a plurality of records; and a processing system including one or more processors that execute computer readable instructions, the computer readable instructions, when executed by the processing system, causing the processing system to: receive a search query containing one or more query terms from a remote device; determine one or more entity types implicated by the search query based on the one or more query terms and the knowledge base, and for each entity type, determining an entity score indicating a likelihood that the search query implicates the entity type based on the knowledge base; identify one or more index clusters from the plurality of index clusters to search based on the one or more entity types implicated by the search query, each index cluster having a plurality of tiers, and each tier including one or more search indexes; generate a query execution plan based on the entity scores of the one or more entity types, the query execution plan indicating, for each identified index cluster, i) a priority assigned to a search of the index cluster and ii) a time constraint assigned to the indicating cluster indicating a maximum amount of time allotted to search the index cluster; perform a consumer driven search on the identified index clusters based on a set of query terms corresponding to the one or more query terms and in accordance with the query execution plan to identify a delivery consideration set of records; generate delivery search results based on the delivery consideration set of records based on the one or more of the plurality of records; transmit the delivery search results to the remote device; and perform a continuation search by, for each index cluster indicated in the query execution plan: assigning a lowest priority and an unlimited time constraint to the set of query terms with respect to the index cluster; inserting the set of query terms in a queue corresponding to the index cluster with other intent queries, each other intent query having a respective priority assigned thereto: searching all tiers of the index cluster using the set of query terms; and updating a continuation consideration set of records based on the searching, wherein the continuation consideration set of records indicates records identified across all of the index clusters indicated in the query execution plan. 17. The search system of claim 13 , wherein: the continuation search at least includes searches of tiers of the selected index clusters that were unsearched during the consumer driven search; the continuation consideration set includes the delivery consideration set; and the computer readable instructions further cause the processing system to: generate continuation search results based on the continuation consideration set; store the continuation search results in a memory cache; receive a second search query containing the one or more query terms of the search query; retrieve the continuation search results from the memory cache; and transmit the continuation search results.