Hi Noel,
On Monday, 9 February 2015 19:14:32 UTC+6:30, Noel Grandin wrote:
>
> Hi
>
>
> On 2015-02-09 02:21 PM, Steve McLeod wrote:
> > final ResultSet resultSet = conn.prepareStatement("SELECT *
> FROM foobar").executeQuery();
> > int rowCount = 0;
> > while (resultSet.next()) {
> > rowCount++;
> > final int columnCount =
> resultSet.getMetaData().getColumnCount();
> > for (int column = 1; column <= columnCount; column++) {
> > final String columnName =
> resultSet.getMetaData().getColumnName(column);
> > final int anInt = resultSet.getInt(columnName);
> > }
> > }
>
> You should rather be retrieving the column names once, and then retrieving
> the result-set columns using the getXXX(int
> columnIndex) methods.
>
>
I agree - that would help my (contrived) case. My actual code doesn't use
meta-data to get column names, but sources the column names from elsewhere.
I can certainly fix the problems on my end.
But I think there is an opportunity to add a tiny performance improvement
in general here. Iterating over a result set, using getXXX(String
columnName) is very common use of JDBC. We're not talking 10% speed
improvement, but perhaps 1% in some cases? I don't know for sure - I'm just
guessing based on the profiling.
> The only other thing I can think of that might speed it up would be to
> modify the current caching code to use a TreeMap
> with a custom comparator and then set the comparator to
> java.lang.String.CASE_INSENSITIVE_ORDER.
> That would avoid the extra String object creation, at the very least.
>
Sounds good. Will java.lang.String.CASE_INSENSITIVE_ORDER be satisfactory?
The Javadocs state: "Note that this Comparator does not take locale into
account, and will result in an unsatisfactory ordering for certain
locales." I think that means it is acceptable for H2's case, but I'm not
certain.
Regards,
Steve
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