On 2/17/2005 2:08 PM, Andrew Sullivan wrote:

> On Thu, Feb 17, 2005 at 01:17:16PM -0500, Jan Wieck wrote:
>> On 2/16/2005 6:46 AM, Andrew Sullivan wrote:
> 
>> >Yes. 
>> 
>> Actually not exactly. The query executed on the subscriber would be
>> 
>>     update example_table set key = '4' where key = '4';
>> 
>> The slony log trigger filters out unchanged columns. If that results in 
>> no column change at all (empty SET clause in the update), it adds the 
>> first key column so that the update becomes valid SQL.
> 
> Sorry, I should have been clearer.  Jan is of course right that the
> trigger filters unchanged columns; but the OP wanted to know if it
> filters out queries which do no work or have no effect.  The answer
> to that, as far as I know, is no, and Jan's example above illustrates
> it.
> 
> A
> 

We (my stomach and I) had been thinking about filtering out NOOP's 
entirely. But that would be in conflict with subscriber side enabled 
user triggers, which do get called even if the update does in fact 
nothing like the above example.

The solution would be another attribute on sl_table which is used to 
define another argument for the log trigger which controls the filter.


Jan

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