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POOptimizing ResultSet fetch performance (Apache Spring, MySQL)
 

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    <p>My problem is this: I am trying to process about 1.5 million rows of data in Spring via JDBCTemplate coming from MySQL. With such a large number of rows, I am using the RowCallbackHandler class as suggested <a href="https://stackoverflow.com/questions/1341254/spring-jdbc-support-and-large-dataset">here</a></p> <p>The code is actually working, but's SLOW... The thing is that no matter what I set the fetch size to, I seem to get approximately 350 records per fetch, with a 2 to 3 second delay between fetches (from observing my logs). I tried commenting out the store command and confirmed that behavior stayed the same, so the problem is not with the writes.</p> <p>There are 6 columns, only 1 that is a varchar, and that one is only 25 characters long, so I can't see throughput being the issue.</p> <p>Ideally I'd like to get more like 30000-50000 rows at a time. Is there a way to do that?</p> <p>Here is my code:</p> <pre><code> protected void runCallback(String query, Map params, int fetchSize, RowCallbackHandler rch) throws DatabaseException { int oldFetchSize = getJdbcTemplate().getFetchSize(); if (fetchSize > 0) { getJdbcTemplate().setFetchSize(fetchSize); } try { getJdbcTemplate().query(getSql(query), rch); } catch (DataAccessException ex) { logger.error(ExceptionUtils.getStackTrace(ex)); throw new DatabaseException( ex.getMessage() ); } getJdbcTemplate().setFetchSize(oldFetchSize); } and the handler: public class SaveUserFolderStatesCallback implements RowCallbackHandler { @Override public void processRow(ResultSet rs) throws SQLException { //Save each row sequentially. //Do NOT call ResultSet.next() !!!! Calendar asOf = Calendar.getInstance(); log.info("AS OF DATE: " + asOf.getTime()); Long x = (Long) rs.getLong("x"); Long xx = (Long) rs.getLong("xx"); String xxx = (String) rs.getString("xxx"); BigDecimal xxxx = (BigDecimal)rs.getBigDecimal("xxxx"); Double xxxx = (budgetAmountBD == null) ? 0.0 : budgetAmountBD.doubleValue(); BigDecimal xxxxx = (BigDecimal)rs.getBigDecimal("xxxxx"); Double xxxxx = (actualAmountBD == null) ? 0.0 : actualAmountBD.doubleValue(); dbstore(x, xx, xxx, xxxx, xxxxx, asOf); } } </code></pre>
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