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POCOPY FROM and C3PO connection pool in Postgres
 

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  1. POCOPY FROM and C3PO connection pool in Postgres
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    <p>I have the follow code in my JAVA program that allows me to copy data from a file into my Postgres database:</p> <pre><code>Connection con = DriverManager.getConnection("jdbc:postgresql://localhost:####/myDb", "myuser", "mypassword"); CopyManager cm = new CopyManager((BaseConnection) con); cm.copyIn("COPY prices FROM STDIN WITH DELIMITER AS ','", new BufferedReader(new FileReader(filepath)), buffersize); </code></pre> <p>This code works fine, but I would like to use a connection pool to manage my connections, as I have this code running for numerous files. So I used <a href="http://www.mchange.com/projects/c3p0/" rel="noreferrer">C3P0</a>.</p> <pre><code>public static final ComboPooledDataSource cpds = new ComboPooledDataSource(); public class MyPooledConnection { MyPooledConnection() throws PropertyVetoException { cpds.setDriverClass("org.postgresql.Driver"); cpds.setJdbcUrl("jdbc:postgresql://localhost:5432/myStockDatabase"); cpds.setUser("myUserName"); cpds.setPassword("myPassword"); cpds.setInitialPoolSize(4); cpds.setMinPoolSize(4); cpds.setMaxIdleTime(30); cpds.setMaxPoolSize(MAX_CONNECTIONS); } public static Connection getConnection() { return cpds.getConnection(); } } </code></pre> <p>However, when i get a connection from the connection pool above and try to use it with CopyManager like in the example below, the code doesn't work</p> <pre><code>Connection pooled_con = MyPooledConnection.getConnection(); CopyManager cm = new CopyManager((BaseConnection) pooled_con); cm.copyIn("COPY prices FROM STDIN WITH DELIMITER AS ','", new BufferedReader(new FileReader(filepath)), buffersize); </code></pre> <p>I'm guessing the issue is with the connection, but i can't seem to figure out what about it is different. I've tried catching the error with SQLException and IOException, but it doesn't catch either. Has anyone encountered this?</p> <p>----<em><strong>UPDATED</strong></em>----</p> <p>Thanks to a_horse_with_no_name the guidance on this. The following code worked for me</p> <pre><code>// Cast the connection as a proxy connection C3P0ProxyConnection proxycon = (C3P0ProxyConnection)cpds.getConnection(); try { // Pass the getCopyAPI (from PGConnection) to a method Method m = PGConnection.class.getMethod("getCopyAPI", new Class[]{}); Object[] arg = new Object[] {}; // Call rawConnectionOperation, passing the method, the raw_connection, // and method parameters, and then cast as CopyManager CopyManager cm = (CopyManager) proxycon.rawConnectionOperation(m, C3P0ProxyConnection.RAW_CONNECTION,arg); cm.copyIn("COPY prices FROM STDIN WITH DELIMITER AS ','", new BufferedReader(new FileReader(filepath)), buffersize); } catch (NoSuchMethodException | IllegalAccessException | IllegalArgumentException | InvocationTargetException e) { // Deal with errors here } </code></pre>
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    1. USJaycal
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      1. POCOPY FROM and C3PO connection pool in Postgres
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    1. COThe complete stack trace of the error is? Why are you initializing a static field from a constructor? And what makes you think that connections returned by C3P0 are instances of BaseConnection (whatever this class might be?)
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      1. USJB Nizet
    2. COWhat do you mean by doesn't work? Is any exception of any type thrown? Does it hang?
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      1. USAHungerArtist
    3. CO@AHungerArtist: "Doesn't work" as in the data in the file is not copied to the table. There is no exception thrown, nor does it hang; it just continues as if the code were executed.
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      1. USJaycal
 

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