3. The one or more storage media of claim 1 , wherein the one or more criteria is associated with a characteristic of data that is processed during performance of an operation that is included in the portion of the execution plan.
1. One or more storage media storing instructions which, when executed by one or more processors, cause: in response to receiving a query, identifying an execution plan that comprises a plurality of sub-plans that includes a first sub-plan and a second sub-plan; wherein the first sub-plan comprises a first operation, of a first type, that can be performed during execution of the execution plan; wherein the second sub-plan comprises a second operation, of a second type that is different than the first type, that can be performed during execution of the execution plan; wherein no sub-plan in the plurality of sub-plans contains all operations that are required to generate a valid result of the query; wherein the execution plan comprises one or more operations that are not in the first sub-plan or the second sub-plan; after determining the execution plan, executing a portion of the execution plan, wherein executing the portion of the execution plan comprises storing, in a buffer associated with a particular size, temporary results of executing the portion, wherein the particular size is less than a size of a table from which the temporary results are generated; in response to determining that an amount of data in the buffer has reached the particular size, determining whether one or more criteria are satisfied; if the one or more criteria are satisfied, then executing the first sub-plan of the plurality of sub-plans without executing the second sub-plan; if the one or more criteria are not satisfied, then executing the second sub-plan of the plurality of sub-plans without executing the first sub-plan; generating a result of the query by completing execution of the execution plan and without reoptimizing the query.