On 01/11/10 18:08, Andy Colson wrote:
On 11/1/2010 12:37 PM, Jonathan Tripathy wrote:
Hi Everyone,
I'm trying to create a server for a database system which will be used
by multiple clients. Of course, table locking is very important. Reading
the Postgresql docs, locking occurs on a transaction-by-transaction
basis.
In our java code, we are doing this:
//Start Code Block
Connection con = "..."
con.setAutoComitt(false);
//Insert SQL here to lock table
String qry1 = "..."
pst1 = con.prepareStatement(qry1)
//Insert code here to add values to prepared statement pst1
pst1.executequery();
String qry2 = "..."
pst2 = con.prepareStatement(qry2)
//Insert code here to add values to prepared statement pst2
pst2.executequery();
con.comitt();
//End Code Block
My question is, would the above block of code be classed as a single
transaction, and would the locking work correctly?
Thanks
Jonny
Table locking is very bad for concurrent access. When a table is
locked, its one user at a time.
PG usually does not need any locks at all. As long as you use
transactions as they were meant to be used (as an atomic operation),
things usually work really well, with no locking at all. You could
read up on MVCC is you were interested.
Without knowing what sql you are running, I can _totally guarantee_
it'll work perfectly with NO table locking. :-)
-Andy
Hi Andy,
Thanks for your reply. Would the above code be classed as a single
transaction then? And if so, I could just simple leave out the line
which says "//Insert SQL here to lock table"?
Thanks
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