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"S. Chen" wrote:
>
> String query = "select * from table1 order by trans_date desc";
> [...]
> while (rs.next()&& count <100) {
> [...]
>
> The problem is soon enough there will be over 10,000
> transactions in the database. If I do it this way, it will be
> not efficient. so I want to use the method setFetchSize(100).
This isn't inefficient on most databases. You've paid the price
of the ORDER BY clause, and for most real DBMSes the code you
have is fine.
Also, setFetchSize has very little to do with this. The fetch
size is just an internal performance hint to the JDBC driver, and
should not be set based on application requirements. The prefetch
row count should be based on row size, packet size, network
congestion, etc.
More relevant, perhaps, is setMaxRows, if your driver supports
it, or SQL equivalents. You should be warned, though, that
limiting the number of rows returned from a query with an ORDER
BY clause may not work. In Oracle, for example, the limiting is
done *before* the sorting. You can check your DBMS documentation
to see if it supports any performance enhancements for limiting
result set size that behave properly with ORDER BY, or
investigate other database-specific tuning, if really necessary.
Like most performance enhancements, it probably isn't.
John L
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