Re: Get the offset of a tuple inside a table

I doesn't realized postgresql can be such clever.

Another problem I just found is after one tuple is deleted, there will be
some slots unoccupied. The offset cannot be computed even know how much
tuples a page can contain.

I need one hash table.

Thanks
--
Pei

On Tue, Sep 21, 2010 at 8:47 PM, Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov
> wrote:

> Pei He wrote:
>
> > The offset is the order of a tuple in a Sequential Scan.
>
> That's not a safe assumption. Try starting a sequential scan against
> a large table on one connection; then before it finishes, start the
> same query on another connection. The second query joins the one
> already in progress and then starts over, "wrapping around".
>
> -Kevin
>