On 04/08/10 12:23, Boxuan Zhai wrote:
I am just considering that there may be some logical mistakes for my rule
rewriting strategy of MERGE actions.
In my current design, if we find that an action type, say UPDATE, is
replaced by INSTEAD rules, we will remove all the actions of this type from
the MERGE command, as if they are not be specified by user from the
beginning. See the test example in my pages for this situation.
https://wiki.postgresql.org/wiki/MergeTestExamples#With_INSTEAD_rules
Now,I am thinking that maybe we should keep the replaced actions in action
list, and just mark them to be "invalid". If one join tuple from the main
plan fits the condition of this action, we will do nothing on it.
This strategy is a little bit different with the current one. If we delete
an action, the tuples that meet it condition will be caught by other
actions. If we keep it, the tuples that match it will be skipped.
I think the new design is more logical, and I wonder your opinion on this
problem.
So if I understood correctly, in the instead rule example you have at
the wiki page, the stock table should contain one row, with the same
balance it had before running the MERGE? Yeah, agreed, that's much more
logical.
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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