jdbc bug/feature?

Hello,

There is a bug (I say) or a lack of proper functionality in JDBC driver regarding batch updates.

The following code is expected to work by some library that I use and it does work with inet tds driver for M$ SQL server. It however does not work with the latest jdbc from cvs or anything older than that either.

PreparedStatements st = c.prepareStatement("insert into my_table (field1, field2) values (?, ?)");

// we have say 30 inserts to do
Iterator it = inserts.iterator();
int i=0;
while(it.hasNext()) {

// there is a maximum batch size of 15, so we must periodically execute it
if(i==batchMax) {
st.executeBatch();
i=0;

// the problem - after this call a PreparedStatement is empty and consequtive binds fail
}

Object [] binds = (Object [])it.next();
st.setString(binds[0]);
st.setString(binds[1]);
st.addBatch();
i++;
}

Upon some research I discovered the problem and found a very simple solution:

In org.postgresql.jdbc2.AbstractJdbc2Statement:

public int[] executeBatch() throws SQLException
{
System.out.println("### executeBatch");
if (batch == null)
batch = new Vector();
int size = batch.size();
int[] result = new int[size];
int i = 0;

// >>> added
// save m_binds and m_sqlFragments because executeUpdate(String) will destroy them
String [] oldFrags = m_sqlFragments;
Object [] oldMBinds = m_binds;
// <<

try
{
for (i = 0;i < size;i++)
result[i] = this.executeUpdate((String)batch.elementAt(i));

}
catch (SQLException e)
{
int[] resultSucceeded = new int[i];
System.arraycopy(result, 0, resultSucceeded, 0, i);

PBatchUpdateException updex =
new PBatchUpdateException("postgresql.stat.batch.error",
new Integer(i), batch.elementAt(i), resultSucceeded);
updex.setNextException(e);

throw updex;
}
finally
{
batch.removeAllElements();
// >> added
// restore m_binds and m_sqlFragments
m_sqlFragments = oldFrags;
m_binds = oldMBinds;
// <<
}
return result;
}

Please consider this as a bug, and patch it in cvs. I did not test this very well, so the described patch may possibly cause some incosistencies somewhere - the people who wrote that class will know best. It does work for my case though.

And thanks for PostgreSQL, I've just started using it and I love it.

- Marko