At runtime first and second cost functions associated with a request for a merge of a main partition of a table with a delta partition of the table can be calculated. The first and second cost functions can respectively quantify an urgency of the merge relative to availability of system resources required to perform the merge and an urgency of the merge relative to other merges. Determining whether the merge should occur can include comparing the calculated first and second cost functions with calculations of other first and second cost functions for other merge requests of one or more other tables. If the merge should occur, a merge thread can be assigned to execute the merge, and execution of the merge by the merge thread can be commenced if at least one merge token representing system resources usable for merge operations is available.