On 02/09/2015 11:37 AM, Marc Balmer wrote:
Currently there are FETCH and the (non standard) MOVE commands to work
on cursors.
(I use cursors to display large datasets in a page-wise way, where the
user can move per-page, or, when displaying a single record, per record.
When the user goes back from per-record view to page-view, I have to
restore the cursor to the position it was on before the user changed to
per-record view.)
I have to "manually" keep track of the cursor position, but in some
cases it would definitely be easier to just query the current cursor
position directly from the database and later use "MOVE ABSOLUTE" to
rewind it to that position. That could be achieved e.g. by a
hypothetical "TELL <cursor-name>" command. It does, however, not exist
and I have not found an alternative. Is there a way to query the
current cusros position at all? If not, does a TELL command sound like
a good or bad idea?
It's the first time I hear anyone wanting that, but I guess it might
come handy sometimes. I think you'd usually still rather keep track of
that in the client, though, because it's easy to do, and it avoids the
extra round-trip to execute the TELL command.
Not sure we'd want to add the TELL keyword for this. Perhaps a
pg_cursor_pos(<cursor name>) function would be better.
You could fairly easily write an extension to do that, btw. A C function
could call GetPortalByName() and peek into the PortalData.portalPos field.
- Heikki
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
