1.1.1

creating a transaction object for the same. Also refer to AutoCommit, IsolationLevel properties of the
SQLFClientConnection class for additional properties related to transactions.
The isolation level for the transaction is set by passing the required System.Data.IsolationLevel to the
BeginTransaction/BeginSQLFTransaction methods. The supported isolation levels are ReadUncommitted,
ReadCommitted, and RepeatableRead.
Internally, any transaction that uses the ReadUncommitted level is implicitly upgraded to ReadCommitted. When
nothing is specified, the transaction uses the ReadCommitted isolation level, which is what will be returned as
the result of the IsolationLevel property (rather than returning Unspecified). In addition the special
IsolationLevel.Chaos denotes an absence of any transaction (Connection.TRANSACTION_NONE in JDBC).
However, the underlying GemFire store still offers a certain amount of data consistency and atomicity as given
in the section Understanding the data consistency model. Using Distributed Transactions in Your Applications
on page 151 provides an overview of the distributed transaction implementation offered in SQLFire and the
semantics for the same.
When a SQLFire transaction throws a SQLFException having a severity of Transaction or greater, the transaction
is implicitly rolled back on the server and there is no need to explicitly roll it back. Conflicts between transactions
(where the same row is being updated by two transactions) and constraint violations cause the transaction to roll
back. The latter case is a limitation caused by the distributed nature of a SQLFire system.
The MSDN documentation for IDbTransaction and DbTransaction provides more details about the API methods
and usage.
Example
// Open a new connection to the network server running on
localhost:1527
string host = "localhost";
int port = 1527;
string connectionStr = string.Format("server={0}:{1}", host,
port);
using (SQLFClientConnection conn = new
SQLFClientConnection(connectionStr)) {
conn.Open();
// create a table
SQLFCommand cmd = new SQLFCommand(
"create table t1 (id int primary key, addr
varchar(20))", conn);
cmd.ExecuteNonQuery();
SQLFTransaction tran =
conn.BeginTransaction(IsolationLevel.ReadCommitted);
cmd.Transaction = tran;
// insert into the table using positional parameters
cmd = new SQLFCommand("insert into t1 (id, addr) values (?,
?)", conn);
cmd.Prepare();
for (int i = 0; i < 1000; i++) {
cmd.Parameters.Clear();
cmd.Parameters.Add(i);
cmd.Parameters.Add("addr" + i);
cmd.ExecuteNonQuery();
}
tran.Commit();
// fire some updates and if any unsuccessful then rollback
the transaction
vFabric SQLFire User's Guide704
vFabric SQLFire Reference