Re: Performance improvement proposal. Removal of toLowerCase calls.

On Thu, Jan 16, 2014 at 2:21 PM, dmp <danap(at)ttc-cmc(dot)net> wrote:

> Jeremy Whiting 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.
>>
> ****************
>
> This is going to break existing applications, if the requirement is to have
> either upper or lowercase. I test explicitly with the MyJSQLView
> application
> the use of mixed case column, key index names because there are
> applications
> that used mixed case. The proper way to handle is quote to handle the mixed
> case so it is store as such.
>
> Perhaps the optimization could check for quoting then do no addition
> process
> and store directly intact. Other wise the optimization could initiate as
> proposed.
>
> danap.
>
>
>
Are you sure ? This is in the resultset, so any column names should have
come back from the db.
Which means that they should come back in lower case anyway.

I would think the current code would break apps that having real mixed case
columns in the database ?

Jeremy's proposal would leave the case alone and store it in the map with
mixed case.

Dave Cramer

dave.cramer(at)credativ(dot)ca
http://www.credativ.ca

> [2]
>> https://github.com/pgjdbc/pgjdbc/blob/REL9_3_STABLE/org/postgresql/jdbc2/
>> AbstractJdbc2ResultSet.java?#L2752
>>
>>
>
>
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