On 01/13/2013 12:28 AM, Noah Misch wrote:
[Catching up on old threads.]
On Sat, Nov 17, 2012 at 03:40:49PM +0100, Hannu Krosing wrote:
On 11/17/2012 03:00 PM, Markus Wanner wrote:
On 11/17/2012 02:30 PM, Hannu Krosing wrote:
Is it possible to replicate UPDATEs and DELETEs without a primary key in
PostgreSQL-R
No. There must be some way to logically identify the tuple.
It can be done as selecting on _all_ attributes and updating/deleting
just the first matching row
create cursor ...
select from t ... where t.* = (....)
fetch one ...
delete where current of ...
This is on distant (round 3 or 4) roadmap for this work, just was
interested
if you had found any better way of doing this :)
That only works if every attribute's type has a notion of equality ("xml" does
not). The equality operator may have a name other than "=", and an operator
named "=" may exist with semantics other than equality ("box" is affected).
Code attempting this replication strategy should select an equality operator
the way typcache.c does so.
A method for making this work as PostgreSQL works now would be to
compare "textual representations" of tuples
create cursor ...
select from t ... where t::text = '(<image of original row>)'
fetch one ...
delete where current of ...
But of course having an operator for "sameness" without needing to convert to
text
would be better
----------------
Hannu
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