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 identifying rows in tables with no PK's. A gross example (that undoubtedly wouldn't work in the real world) would be using TID's. A real-world implementation might be based on a hidden serial column.
Jim C. Nasby, Database Architect jim(at)nasby(dot)net
512.569.9461 (cell) http://jim.nasby.net
In response to
pgsql-hackers by date
|Next:||From: Heikki Linnakangas||Date: 2012-05-03 06:14:04|
|Subject: Re: Latch for the WAL writer - further reducing idle wake-ups.|
|Previous:||From: Jim Nasby||Date: 2012-05-03 04:24:38|
|Subject: Re: Re: xReader, double-effort (was: Temporary tables under