NAME
Collection::CrcColl - experimental class for collections
TYPES
varchar => string strin binary => hex2raw ( raw2hex) BINARY refhash => { var1=>'1', var2=>0} string ('var1=0 , var=2')
_expand_rules
Owerwrite method and add check _crc fields
_prepare_where <query hash>
return <where> expression or undef else