Unlimited chunk size (--chunk-size-limit=0) inhibits checksumming of single-nibble tables

Unlimited chunk size (--chunk-size-limit=0) inhibits checksumming of single-nibble tables

pt-online-schema-change 2.2.13 @ line 9068:

PTDEBUG && _d('Table on',$slave->name(),'has', $n_rows, 'rows');
if ( $n_rows && $n_rows > ($tbl->{chunk_size} * $limit) ) {
    PTDEBUG && _d('Table too large on', $slave->name());
    push @too_large, [$slave->name(), $n_rows || 0];
}

Where $n_rows is the estimate number of rows in the slave's table, and the $limit is the --chunk-size-limit. So it's multiplying by zero, and this shows the slave's table as always larger.

How to repeat: examine code and documentation (http://www.percona.com/doc/percona-toolkit/2.1/pt-online-schema-change.html#cmdoption-pt-online-schema-change--chunk-size-limit states "You can disable oversized chunk checking by specifying a value of 0." but doesn't warns about this corner case)

How to fix: ignore -for this check- --chunk-size-limit if equals zero.