1. A computer-implemented method comprising: selecting, from a workload set, a set of targeted database query language statements for performance analysis, wherein the workload set comprises database query language statements; executing, on a first database system, the set of targeted database query language statements; wherein executing the set of targeted database query language statements on the first database system comprises gathering a first set of performance data about the execution of each database query language statement of said targeted database query language statements on the first database system; executing, on a second database system, the set of targeted database query language statements, wherein the database of the second database system is a modified version of the database of the first database system; wherein executing the set of targeted database query language statements on the second database system comprises gathering a second set of performance data about the execution of said each database query language statement of said targeted database query language statements on the second database system; wherein each of the first set of performance data and second set of performance data comprises statistics based on at least one of the following: (a) CPU time consumed to execute said each database query language statement of said set of targeted database query language statements, (b) buffer reads incurred to execute said each database query language statement of said set of targeted database query language statements, and (c) disk reads incurred to execute said each database query language statement of said set of targeted database query language statements; comparing the first set of performance data with the second set of performance data; and generating information that indicates a result of the comparison, wherein the information that indicates a result of the comparison includes a difference in a total performance metric for executing the set of targeted database query language statements between the first database system and the second database system; and wherein the information that indicates a result of the comparison includes, for each database query language statement in the set of targeted database query language statements, a difference in a performance metric for executing said each database query language statement between the first database system and the second database system.
8. The computer-implemented method of claim 1 , wherein the first set of performance data includes, for each database query language statement in the set of targeted database query language statements, a total execution time.