Re: CURRENT OF cursor without OIDs

From: "Mikheev, Vadim" <vmikheev(at)SECTORBASE(dot)COM>
To: Hiroshi Inoue <Inoue(at)tpf(dot)co(dot)jp>
Cc: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Zeugswetter Andreas SB SD <ZeugswetterA(at)spardat(dot)at>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: CURRENT OF cursor without OIDs
Date: 2001-08-24 17:06:56
Message-ID: 3705826352029646A3E91C53F7189E32016752@sectorbase2.sectorbase.com
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> Oops I'm referring to client side cursors in our ODBC
> driver. We have no cross-transaction cursors yet though
> I'd like to see a backend cross-transaction cursor also.

Ops, sorry.
BTW, what are "visibility" rules for ODBC cross-tx cursor?
No Repeatable reads, no Serializability?
Do you hold some locks over table while cursor opened
(I noticed session locking in lmgr recently)?
Could ODBC cross-tx cursors be implemented using server
cross-tx cursors?

> > I think we'll be able to restore old tid along with other tuple
> > data from rollback segments, so I don't see any problem from
> > osmgr...
>
> How do we detect the change of tuples from clients ?

What version of tuple client must see? New one?

> TIDs are invariant under osmgr. xmin is about to be
> unreliable for the purpose.

Seems I have to learn more about ODBC cross-tx cursors -:(
Anyway, *MSQL*, Oracle, Informix - all have osmgr. Do they
have cross-tx cursors in their ODBC drivers?

Vadim

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