Gurjeet Singh wrote:
% Hi All,
%
% As I mentioned in the last conference call, I could not implement a
% workaround for CONNECT BY in plpgsql; that was because of a limitation in
% the way plpgsql handles the pseudo datatype RECORD.
...
% and both these instances SELECT the same data: given an action_id, give me
% all the pre-requisites in order.
%
% So I have written two plpgsql functions to accomplish what these two
% instances need. Please find the code and a few examples attached.
%
% Using these functions, the queries can now be written as:
%
% ./backend/server/rhnAction.py:
%
% _query_lookup_action = rhnSQL.Statement("""
% select sa.action_id, sa.status
% from rhnServerAction sa,
% (
% select id
% from rhn_get_action_prerequisites( :action_id )
% as f( id numeric, prerequisite numeric, level int)
% /**** start with id = :action_id
% connect by prior id = prerequisite ****/
% ) a
% where sa.server_id = :server_id
% and sa.action_id = a.id
% """)
CONNECT BY creates a "tree select". Can the above select with
rhn_get_action_prerequisites() handle multi level dependencies as well?
I.e. for
id prerequisite
1 NULL
2 1
3 1
21 NULL
22 21
23 22
the result of
select id
from rhnAction
start with id = 21
connect by prior id = prerequisite
is
21
22
23
.
--
Michael Mráka
Satellite Engineering, Red Hat
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