Hey Frank,
Try opening up a repl, and running this *for* comprehension.
(def user_textfile [[:id1 {:name 'Frank'}] [:id3 {:name 'Tim'}]])
(def user_database [[:id1 {:age 38}] [:id2 {:age 27}] [:id3 {:age 18}]
[:id4 {:age 60}]])
(for [i user_textfile
j user_database
:when (= (first i) (first j))]
{(first i) (merge (second i) (second j))})
*({:id1 {:age 38, :name Frank'}} {:id3 {:age 18, :name Tim'}}) ;; result
from repl *
Hth
Tim Washington
Interruptsoftware.com <http://interruptsoftware.com>
On Sun, Mar 9, 2014 at 5:33 AM, Frank Behrens <fbehr...@gmail.com> wrote:
> Hi,
>
> i'm investigating if clojure can be used to solve the challenges and
> problems we have at my day job better than ruby or powershell. A very
> common use case is validating data from different systems against some
> criteria. i believe clojure can be our silver bullet, but before that, it
> seems to be required to wrap my head around it.
>
> So I am starting in the first level with the challenge to validate some
> data from the user database against our active directory.
>
> I already have all the parts to make it work: Which is to make a hash by
> user_id from the database table, export a textfile from AD, each line
> representing a user, parse it, merge the information from the
> user_table_hash, and voila.
>
> I did not finish to implement this. So I don't know if this naive approach
> will work with 400.000 records in the user database and 100.000 in the
> textfile.
> But I already think about how I could implement this in a more memory
> efficient way.
>
> So my simple question:
>
> I have user_textfile (100.000 records) which can be parsed into a
> unordered list of user-maps.
> I have user_table in the database(400.000 record) which I can query with
> order and gives me an ordered list of user-maps.
>
> So I would first order the user_textfile and then conj the user_table
> ordered list into it, while doing the database query.
> Is that approach right ? How would I then merge the two ordered lists like
> in the example below?
>
> (defn user_textfile
> ([:id1 {:name 'Frank'}]
> [:id3 {:name 'Tim'}]))
>
> (defn user_database
> ([:id1 {:age 38}]
> [:id2 {:age 27}]
> [:id3 {:age 18}]
> [:id4 {:age 60}]))
>
> (merge-sorted-lists user_database user_textfile)
> =>
> ([:id1 {:name 'Frank' :age 38}]
> [:id3 {:name 'Tim' :age 18}]))
>
> Any feedback is appreciated.
> Have a nice day,
> Frank
>
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