insert batch & execute performance

[Globe Trotter]

Hi,

I have
- a table about 100MB size
- and try addBatch inserts around 1MB each time
- "?rewriteBatchedStatements = true" is to login added
- @@global.max_allowed_packet = 256000000
- @@global.key_buffer_size = 256000000;
- Code in Java:
conn.setAutoCommit(false);
String query = "insert into " + TABLE + " (id, partInfo) values (?, ?)";
PreparedStatement pstmt = conn.prepareStatement(query);

for(..)
{
pstmt.setInt(ID, jdosym.getId());
pstmt.setBytes(PART, jdosym.getPart());
pstmt.addBatch();

if (i % 1000 == 0) pstmt.executeBatch();
}

pstmt.executeBatch();
conn.commit();
conn.setAutoCommit(true);

pstmt.close();

The Problem is, the execute batch is very very slow!? What can be the reason?

Thanks in advamce,

GlobeTrotter