On 9/17/07, Thibaut Barrère <[EMAIL PROTECTED]> wrote:
> Great - keep me posted!
>
> Raw ideas again, but what I've been doing at some point in my tests
> was traversing ObjectSpace to get all the subclasses of
> ActiveWarehouse::Fact or Dimension, and assign them table_name =
> "tmp_" + table_name (unless the table_name already begins with "tmp_",
> which can happen if you include a "common.rb" in each of your control
> files then call this method to ensure every AR in scope is properly
> "temporised").
>
> Basically I think that unless specified otherwise, when
> use_temp_tables is called with true, we could handle the AR patching
> behind.
>
> If you find this (or something similar) interesting and not too much
> black-magic, I could work on a patch (I will do it for myself anyway
> when you'll have fixed the temp table functionality).
So this would allow you to easily use the AR objects...yes, I'd like
to see this happen, and I think it could be mixed into AR::Base at
runtime if temp tables are being used, something overriding table_name
perhaps?
On a related note I've actually found a better way to create the temp
table with MySQL, using two statements. It'll require an update to
adapter extensions, but I think it's the right way to go.
> Still on this topic, here's a use case which I'd like to improve:
>
> use_temp_tables
> # use a variable for further reference
> table = "date_dimension"
> ...
> destination :table => table # (handles temp table mapping alone as I
> seem to remember)
>
> # this won't work because the table is not translated to the temp table
> screen(:fatal) do
> connection.query("select distinct customer_type from #{table}")
> end
>
> Basically, I think we'd just need a small helper which would do :
> def table_name(table_name)
> use_temp_tables? ? "tmp_#{table_name}" : table_name
> end
>
> (that's the idea, not the implementation)
>
> to allow a more seamless use in the screen.
Yes, I think that would be a good helper, although if possible have it
get the table name from ETL::Engine.table_name.
> Now all this is just polishing - but I think it brings value.
Agreed.
V/r
Anthony
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