Обсуждение: some questions

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some questions

От
Ludwig Lim
Дата:
Hi:

1)
    When I do the ff sql statement
    select foo
    from bar
    limit n;

    Is it the same as :
    select foo
    from bar
    order by oid
    limit n;

   The the displaying of the result of a SELECT
statement without the ORDER BY clause reflects the
chronological order of insertion? If yes, Does this
this mean that if we don't need use to use SEQUENCES
if we just want to keep track the order of insertion
by chronological order?
   Can we oid to keep track of the order of insertion
by chronological order?

2)Just for clarification. In the FAQ:
4.16.3) Don't currval() and nextval() lead to a race
condition with other users?
 No. This is handled by backends.

  So this means the sequences doesn't affect speed of
insertion. Is this correct?

Thank you very much,

ludwig





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Re: some questions

От
Bruno Wolff III
Дата:
On Fri, Jul 26, 2002 at 19:26:15 -0700,
  Ludwig Lim <lud_nowhere_man@yahoo.com> wrote:
> Hi:
>
> 1)
>     When I do the ff sql statement
>     select foo
>     from bar
>     limit n;
>
>     Is it the same as :
>     select foo
>     from bar
>     order by oid
>     limit n;

No. If you don't use order by then there is no guarenteed order.