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.
Does this hint that postgreSQL also needs an sameness operator
( "is" or "===" in same languages).
Or does "IS NOT DISTINCT FROM" already work even for types without
comparison operator ?
--------------
Hannu
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