remove setting getting transaction isolation on connect, add tests to see if we can set and retrieve the transaction isolation level

Author: davecramer

connection.c

@@ -1094,14 +1094,6 @@ LIBPQ_CC_connect(ConnectionClass *self, char *salt_para)
 
 	if (ret = LIBPQ_connect(self), ret <= 0)
 		return ret;
-	res = CC_send_query(self, ISOLATION_SHOW_QUERY, NULL, READ_ONLY_QUERY, NULL);
-	if (QR_command_maybe_successful(res))
-	{
-		handle_show_results(res);
-		ret = 1;
-	}
-	else
-		ret = 0;
 	QR_Destructor(res);
 
 	return ret;

test/expected/commands.out

@@ -4,4 +4,5 @@ Testing VACUUM with SQLPrepare/SQLExecute...
 Disabling autocommit...
 Testing VACUUM with SQLExecDirect...
 Testing VACUUM with SQLPrepare/SQLExecute...
+Retrieved isolation level: 2
 disconnecting

test/src/commands-test.c

@@ -73,6 +73,24 @@ int main(int argc, char **argv)
 	rc = SQLFreeStmt(hstmt, SQL_CLOSE);
 	CHECK_STMT_RESULT(rc, "SQLFreeStmt failed", hstmt);
 
+	
+	rc = SQLSetConnectAttr(conn, SQL_ATTR_TXN_ISOLATION, (SQLPOINTER)SQL_TXN_READ_COMMITTED, SQL_IS_UINTEGER);
+	CHECK_CONN_RESULT(rc, "SQLSetConnectAttr failed", conn);
+
+	/* Verify the isolation level was set correctly using SQLGetConnectAttr */
+	SQLUINTEGER isolation_level;
+	rc = SQLGetConnectAttr(conn, SQL_ATTR_TXN_ISOLATION, &isolation_level, SQL_IS_UINTEGER, NULL);
+	CHECK_CONN_RESULT(rc, "SQLGetConnectAttr failed", conn);
+	
+	printf("Retrieved isolation level: %u\n", isolation_level);
+	if (isolation_level != SQL_TXN_READ_COMMITTED) {
+		printf("ERROR: Expected %ld (SQL_TXN_READ_COMMITTED), got %u\n", SQL_TXN_READ_COMMITTED, isolation_level);
+		exit(1);
+	}
+
+	rc = SQLFreeStmt(hstmt, SQL_CLOSE);
+	CHECK_STMT_RESULT(rc, "SQLFreeStmt failed", hstmt);
+
 	/* Clean up */
 	test_disconnect();