Re: Implementation of LIMIT on DELETE and UPDATE statements

Yury Bokhoncovich <byg@center-f1.ru> writes:
> Imagine typical usage of LIMIT/OFFSET: pagination of a web-output.
> Say, the output is fetched thru "select id,body from articles limit 10
> offset 20".
> Now, content-admin, surfing the content and looking to the page say 2,
> wanna drop all info on THAT page 2.
> Guess how it could ease the life for programmer?8)

Only until the first time he drops the wrong page that way.

The above is really a perfect example of why this feature isn't safe:
it would lead people to make unwarranted assumptions.  The fact that
such-and-such a tuple appeared second in the output of LIMIT 10 OFFSET
20 does *not* mean that it would be selected by LIMIT 1 OFFSET 21.  The
planner is entitled to (and often does) choose different query plans
depending on the limit/offset values.

            regards, tom lane