Re: For cursors, there is FETCH and MOVE, why no TELL? - Mailing list pgsql-hackers

From Pavel Stehule
Subject Re: For cursors, there is FETCH and MOVE, why no TELL?
Date
Msg-id CAFj8pRDsz6Ur-9WLOLsuHyqVN70Pfg7mV4ugTpOAWaPCv=5K_w@mail.gmail.com
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In response to For cursors, there is FETCH and MOVE, why no TELL?  (Marc Balmer <marc@msys.ch>)
Responses Re: For cursors, there is FETCH and MOVE, why no TELL?  (Marc Balmer <marc@msys.ch>)
List pgsql-hackers
Hi

2015-02-09 10:37 GMT+01:00 Marc Balmer <marc@msys.ch>:
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 sounds like good idea.

Do we need a new statement? We can implement returning the position to MOVE statement. It returns a delta, but it can returns a absolute position too.

Regards

Pavel




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