Databases
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Postsdbo
PO
 

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    <p>I've had the very same scenario (in a slightly different setting). I was not going for JdbcTemplate but for MappingSQLQuery. I think, at least for the query it better suited my needs. Given you would be willing to change, the code could look like this</p> <pre><code>MappingSQLQuery selector = ...; executor.execute(new Runnable() { public void run() { List&lt;WrapObject&gt; list = selector.execute(); for (WrapObject object : list) { while (!queue.offer(object)) { Thread.sleep(100); } } while (!queue.offer(WrapObject.NULL_OBJECT)) { Thread.sleep(100); } } }); executor.execute(new Runnable() { public void run() { WrapObject object; while ((object = queue.take) != WrapObject.NULL_OBJECT) { outboundJdbcTemplate.update(INSERT_QUERY, object.getParam1(),...) } } }); </code></pre> <p>Given a suitable definition of WrapObject, this should do the trick. </p> <p>Working a lot with performance-critical DB-Systems I found the following two things.</p> <ol> <li><p>Often, reimplementing the Spring mappers gives you a better control over the things happening to the database (especially batch-updates, compile-time of PreparedStatements, setting batch-sizes)</p></li> <li><p>If you take a peek at the code, you will learn, that the part of the over-generic Spring-JDBC classes relevant to you is mostly some 10-20 lines and easily reimplemented for your sepcific case while speeding up your application significantly</p></li> <li><p>Depending on your database you might wish to use more than one reader/writer. I have worked with Oracle-Clusters where eight parallel read-processes don't even start to put a significant load on the hardware</p></li> </ol>
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    1. POExtract and Insert concurrently into database using JdbcTemplate and BlockingQueue
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    1. USJonathan
    1. USJonathan
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    1. COWouldn't the selector add all the rows into memory at the moment you execute it?
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    2. CONo, the selector onl;y fetches `fetchSize` (defaultvalue Oracle:10, MySQL:1) tuples of the ResultSet into memory. Fetch is automatically extended, once you reach the end of the prefetched list.
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    3. COSo you are saying that the list of WrapObject is full of fetchSize rather than WrapObjects? I thought the list was full of all the objects returned from the query. And then you put each of those object from the list into the queue. IF THAT IS NOT THE CASE, could you please clarify?
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