cant these be triggers directly on the table ?
if not, Id just attach a ColumnDefault to the columns in question,
which call the appropriate SQL function, and wait for me to fix the
ticket that allows ColumnDefaults to be used upon update as well as
insert.
On Mar 3, 2006, at 11:16 AM, Alan Franzoni wrote:
Il Wed, 1 Mar 2006 11:19:47 -0500, Michael Bayer ha scritto:
[cut]
I think I wasn't able to explain my point properly. I'm using some
database
triggers on pgsql, the trigger functions (kind of python-psycopg
quoted,
since they're taken from a cursor.execute() statement) are:
CREATE OR REPLACE FUNCTION trashlogger() \
RETURNS \"trigger\" AS \
$BODY$ \
begin \
INSERT INTO tobetrashed VALUES ( DEFAULT,
TG_RELNAME,OLD.id,CURRENT_TIMESTAMP ); \
RETURN NULL; \
end;$BODY$ \
LANGUAGE \'plpgsql\' VOLATILE; \
ALTER FUNCTION trashlogger() OWNER TO postgres;
CREATE OR REPLACE FUNCTION ts_updater() \
RETURNS \"trigger\" AS \
$BODY$ \
begin \
new.last_upd = CURRENT_TIMESTAMP; \
return new; \
end; \
$BODY$ \
LANGUAGE \'plpgsql\' VOLATILE;')
If an update occurs, the last_upd column in the record gets
updated. If a
delete occurs, a new record is inserted in the 'tobetrashed' table,
containing the name of the table from which the record was trashed
and the
id of the trashed record.
All of this is used to manage a simple asynchronous multimaster
replication
system on some low-traffic databases.
in sqlalchemy, it would be great to have the opportunity to modify a
statement on-the-fly when an UPDATE occurs (just like the ts_updater()
function) or to attach a new statement (to be executed before the
deletion)
when a DELETE occurs. Sqlalchemy already figures out when an update is
really needed, so there would be no unnecessary commits.
I realize this could be complex, or simply beyond the scope of
sqlalchemy.
I would try implenting it myself, but I'm still studying sqlalchemy's
internals and I haven't grasped everything yet, so I need a 'clue'
on what
way should I take first.
--
Alan Franzoni <[EMAIL PROTECTED]>
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