Question

I’m using Npsql with PostgreSQL. I want to see uncommitted changes of one transaction in a different one.

This is how I create my connection and transaction:

// create connection
m_Connection = new NpgsqlConnection(connectionString);
m_Connection.Open();

//create transaction
m_Transaction = m_Connection.BeginTransaction(IsolationLevel.ReadUncommitted);

In one thread I insert a row like so:

 NpgsqlCommand command = CreateCommand("INSERT INTO TABLEA  ....", parameters, commandTimeout)
 command.ExecuteNonQuery();

and process something else without committing or rolling back the transaction.

In a different thread I read a row like so:

 NpgsqlCommand command = CreateCommand("SELECT COUNT(*) FROM TABLEA", parameters, commandTimeout);
 command.ExecuteScalar();

but somehow I don’t see the results of the first INSERT. I don’t see the results of the insert in pgAdmin either (even after running SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED).

What am I doing wrong? Any help will be appreciated.

Answer 1

PostgreSQL does not support uncommitted reads.

You will never be able to see changes from other transactions that are not committed.