[
http://issues.apache.org/jira/browse/DERBY-1876?page=comments#action_12436898 ]
Daniel John Debrunner commented on DERBY-1876:
----------------------------------------------
I've thought in the past about having the common statistic information in a
language ResultSet implementation that could wrap the real langugae ResultSet.
Then the ResultSetFactory would return a instance of the real ResultSet wrapped
with a StatisticsResultSet when timing etc. was enabled. The
StatisticsResultSet would have code like:
class StatisticsResultSet {
private long openTime;
private final ResultSet rs;
pubic void openCore() {
long s = System.currentTimeMillis();
rs.openCore();
long e = System.currentTimeMillis();
openTime += (e -s);
}
This then removes the common fields and code to get the times from all the
ResultSet classes, also leading to consistency.
The issue with this that code that performs instanceof checks to get specific
behaviour of a ResultSet no longer works, though there are solutions to that:
A) Don't do it, it breaks the api in that the ResultSetFactory says it is
returning a ResultSet, so that's all the callers should depend on.
B) Follow the JBDC wrapper model, have a getRealResultSet() call in
ResultSet api which would return this for most implementations, but the wrapped
rs for StatisticsResultSet. Then code that needed to access the specific class
would use the return from that method.
> Investigate overhead of JDBC layer and compiled activation code for simple
> embedded read-only, forward ResultSets
> -----------------------------------------------------------------------------------------------------------------
>
> Key: DERBY-1876
> URL: http://issues.apache.org/jira/browse/DERBY-1876
> Project: Derby
> Issue Type: Improvement
> Components: JDBC, Performance
> Reporter: Daniel John Debrunner
> Priority: Minor
> Attachments: derby1876.java
>
>
> For simple ResultSet usage like:
> ResultSet rs = ps.executeQuery();
> while (rs.next()) {
> rs.getInt(1);
> rs.getInt(2);
> rs.getInt(3);
> }
> rs.close();
> it would be interesting to see how much overhead could be removed with simple
> changes, or possibly removed if there was a simple ResultSet implementation
> for forward only, read-only ResultSet, and the more complete implementation
> for all other ResultSet types such as updateable and/or scrollable. Has
> introducing updateable ResultSets, for example, degraded the performance of
> read-only ResultSets? Could code be changed so that a typical read-only
> Resultset is not affected by the code required for richer ResultSets?
--
This message is automatically generated by JIRA.
-
If you think it was sent incorrectly contact one of the administrators:
http://issues.apache.org/jira/secure/Administrators.jspa
-
For more information on JIRA, see: http://www.atlassian.com/software/jira
