This is a related issue, but since I just got involved with Solr yesterday and got a jira account today, I am reluctant to make a career-limiting error!
If it is indeed valid, perhaps someone else can make it a full-fledged separate issue!
Perusing: JdbcDataSource @version $Id: JdbcDataSource.java 696539 2008-09-18 02:16:26Z ryan
Issue: MySQL fetchSize driver bug
Both my experience and according to: http://benjchristensen.wordpress.com/2008/05/27/mysql-jdbc-memory-usage-on-large-resultset/
MySQL does not handle properly any fetchSize > Integer.MIN_VALUE, and the entire ResultSet is transfered and loaded into memory, which for large ResultSets can result in an out of memory.
57: private int batchSize = FETCH_SIZE;
326: private static final int FETCH_SIZE = 500;
Is is, this code will invoke this bug for MySQL for large ResultSets.
Even for smaller ResultSets that do not cause an out of memory error, having all the ResultSet in memory will unnecessarily use up memory.
The work around for this MySQL issue is:
From the blog entry, see also: