Re: LIMIT for UPDATE and DELETE

(2014/08/25 15:48), Etsuro Fujita wrote:
> (2014/08/15 6:18), Rukh Meski wrote:
>> Based on the feedback on my previous patch, I've separated only the
>> LIMIT part into its own feature.  This version plays nicely with
>> inheritance.  The intended use is splitting up big UPDATEs and DELETEs
>> into batches more easily and efficiently.
>
> Before looking into the patch, I'd like to know the use cases in more
> details.

Thanks for the input, Amit, Kevin and Jeff!  I understand that the patch 
is useful.

I've looked at the patch a bit closely.  Here is my initial thought 
about the patch.

The patch places limit-counting inside ModifyTable, and works well for 
inheritance trees, but I'm not sure that that is the right way to go.  I 
think that this feature should be implemented in the way that we can 
naturally extend it to the ORDER-BY-LIMIT case in future.  But honestly 
the patch doesn't seem to take into account that, I might be missing 
something, though.  What plan do you have for the future extensibility?

I think that the approach discussed in [1] would be promissing, so ISTM 
that it would be better to implement this feature by allowing for plans 
in the form of eg, ModifyTModifyTable+Limit+Append.

Thanks,

[1] http://www.postgresql.org/message-id/26819.1291133045@sss.pgh.pa.us

Best regards,
Etsuro Fujita