Re: currval() within one statement

sad wrote:
> Guillaume Lelarge wrote:
>> sad wrote:
>>> A. Kretschmer wrote:
>>>
>>>>> is it expected that the currval() changes its value between calls 
>>>>> within one statement ?
>>>
>>>> Conclusion, don't call nextval() within a TRIGGER, and insert either
>>>> nextval() for the column or omit this column.
>>>
>>> I only note that i still want to discuss the titled problem or to be
>>> given an exact pointer to documentation regarding the currval() behavior
>>> in the described situation, that i had.
>>>
>>
>> Well, your situation is weird, to say the least. currval() doesn't 
>> change the value of a sequence. Adding a trigger that calls nextval() 
>> will change the value. But you're not telling us which kind of 
>> trigger... per statement or for each row ? if it's for each row, then 
>> that's quite understandable.
> 
> my fault --  i forgot to say.
> The trigger is "for each row".
> 
> It is understandable, i agree, but it is surprising -- alternative 
> behavior (constant result off currval()) is understandable too.
> 

It isn't surprising. A "for each row" trigger will execute the trigger 
function for each individual row, which will executes nextval each 
time... so each currval will get a different value.


-- 
Guillaume. http://www.postgresqlfr.org http://dalibo.com