On Aug 11, 2007, at 8:58 AM, Joshua D. Drake wrote:
Heikki Linnakangas wrote:
Enrico Weigelt wrote:
I'm often using writable views as interfaces to clients, so
they only see "virtual" objects and never have to cope with
the actual storage, ie. to give some client an totally
denormalized view of certain things, containing only those
information required for certain kind of operations.
Now I've got the strange feeling that this makes updates
slow, since it always has to run the whole view query to
fetch an record to be updated (ie. to get OLD.*).
There is some overhead in rewriting the query, but it shouldn't be
significantly slower than issuing the statements behind the view
directly. I wouldn't worry about it, unless you have concrete
evidence
that it's causing problems.
I don't know about that, at least when using rules for partitioning
the
impact can be significant in comparison to triggers.
That's because you have to re-evaluate the input query for each rule
that's defined, so even if you only have rules for 2 partitions in a
table (which is really about the minimum you can have, at least for
some period of overlap surrounding the time when you switch to a new
partition), you're looking at evaluating every input query twice.
In this case, the rules presumably are just simply re-directing DML,
so there'd only be one rule in play at a time. That means the only
real overhead is in the rewrite engine.
--
Decibel!, aka Jim Nasby decibel@xxxxxxxxxxx
EnterpriseDB http://enterprisedb.com 512.569.9461 (cell)
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