I am even wondering why we would be doing that and even worse using a locale to do it.
AFAICT, the db would return everything in lower case anyway, and if the column really had mixed case it should be returned with it's original case intact.
On Thu, Jan 16, 2014 at 10:44 AM, Jeremy Whiting <jwhiting@redhat.com> wrote:
Hi, I would like to propose an optimization to improve performance in the jdbc driver. The performance improvement has been tested on commodity hardware using an industry standard Java benchmark. The overall benchmark metric reports an improvement in performance. Profiling using sampling showed calls reduced from 1100 to 0 when the benchmark workload is running.
The optimization will eliminate calls to the method toLowerCase(java.util.Locale). This in the pg-jdbc org.postgresql.jdbc2.AbstractJdbc2ResultSet.findColumnIndex(java.lang.String) method when setting up the column index registry.
For the optimization to be enabled I suggest relying on a new system property. Making the existing functionality the default behaviour to ensure existing applications do not break when the driver is upgraded.
The change removes the call toLowerCase when putting items in the registry [1]. Essentially what's being proposed is removing sanitizing the key names. For best performance application code should pass SQL to the driver with column names already folded to lower case. But upper case names will still be matched in the second lookup [2] in the method. For this optimization to work this feature introduces a requirement on applications. To use all lower or upper case column names.
Are there other factors that might affect this optimization that need to be taken into consideration ?
