pt-archiver doesn't reconnect and retry its SELECT queries

[Baron Schwartz]

pt-archiver queries are likely to be killed by automatic query killers. (Ask me how I know.) The tool then exits with a message such as the following:

DBD::mysql::st execute failed: Lost connection to MySQL server during query [for Statement "SELECT /*!40001 SQL_NO_CACHE ...

Where the code in question is the $get_sth execute here:

         PTDEBUG && _d('Fetching rows in next chunk');
         trace('select', sub {
            my $select_start = time;
            $get_sth->execute(@{$lastrow}[@asc_slice]);
            $last_select_time = time - $select_start;
            PTDEBUG && _d('Fetched', $get_sth->rows, 'rows');
            $statistics{SELECT} += $get_sth->rows;
         });

This makes the tool not very resilient. I think it should catch errors there and reconnect, then try again --retries times.

[Baron Schwartz (baron-xaprb)]

It also needs to retry the initial SELECT:

4335 $get_sth = $get_first; # Later it may be assigned $get_next
4336 trace('select', sub {
4337 my $select_start = time;
4338 $get_sth->execute;
4339 $last_select_time = time - $select_start;
4340 $statistics{SELECT} += $get_sth->rows;
4341 });

That can get killed easily, too, if it runs for a long time (which it does sometimes).

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PT-1019