On 4/29/12 6:03 AM, Simon Riggs wrote:
>> The DML-WITH-LIMIT-1 is required to do single logical updates on tables
>> > with non-unique rows.
>> > And as for any logical updates we will have huge performance problem
>> > when doing UPDATE or DELETE on large table with no indexes, but
>> > fortunately this problem is on slave, not master;)
> While that is possible, I would favour the do-nothing approach. By
> making the default replication mode = none, we then require a PK to be
> assigned before allowing replication mode = on for a table. Trying to
> replicate tables without PKs is a problem that can wait basically.
>
Something that a in-core method might be able to do that an external one can't would be to support a method of uniquely
identifyingrows in tables with no PK's. A gross example (that undoubtedly wouldn't work in the real world) would be
usingTID's. A real-world implementation might be based on a hidden serial column.
--
Jim C. Nasby, Database Architect jim@nasby.net
512.569.9461 (cell) http://jim.nasby.net