I have searched a lot but couldn't find an answer to this. I am using the construct

$dbh = DBI->connect($dsn, $user, $pass, { RaiseError => 1, AutoCommit 
+=> 0 });
        #Here we open a locked access to the database 
        my $select_handle;
        eval{
            $dbh->do("BEGIN WORK");
            $dbh->do("LOCK TABLE $table");

            ###CODE
         $dbh->do("COMMIT WORK");  
        };
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To access a Postgres db in a exclusive way. This construct works fine but each time it is used a Warning comes out

WARNING:  there is already a transaction in progress
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Someone knows how can I avoid it? It is little annoying this print in the log file of my program which accesses tens of times to the database. Thanks in advance