openstack team mailing list archive

[Greg Holt <gholt@xxxxxxxxxxxxx>]

Okay, I give up then. Not sure what's different with what you have vs. Swift dbs. Just trying to offer up what we do and have been doing for a while now.

On May 25, 2011, at 2:40 PM, Jay Pipes wrote:

> On Wed, May 25, 2011 at 3:32 PM, Greg Holt <gholt@xxxxxxxxxxxxx> wrote:
>> select w from x where y > marker order by y limit z
>> 
>> This gives you consistent pagination, means the database doesn't have to count matching rows to find an offset, and means you could shard by y later in life if you need to scale that much.
> 
> Sorry, that doesn't make any sense to me. An offset is part of the
> LIMIT X OFFSET Y clause. Your query above would return ALL the rows
> that match WHERE y > marker. That's not what we want. We want a
> segment of those rows.
> 
> In addition, your SQL expression does not return consistent result
> sets if the Y column does not have an increasing value over time. New
> records inserted into the table will pop into random pages of results
> if the Y column does not have a strictly increasing ordering.
> 
> -jay