Hello All, I'm not sure you have a problem you can solve lasily here. Simplifying the problem immensely, if you have two one-to-one mappings, involving three completely disjoint orderable datatypes: A <-> B B <-> C and you want to produce a list of C in the order suggested by A, there are two reasonable ways of doing it: - merge then sort - get both lists sorted in B order (assumed free) - walk down finding B's that match (you can tell what to discard because it's less than the head of the other one) (linear) - sort on A (log-linear; not lazy) - sort then lookup - get the first list in A order (assumed free) - get the second list as a dictionary of B->C (assumed free) - walk the first list looking up C values in the second (log per lookup; log-linear in total; not lazy on B->C) If you want to do this in python, I think sort-then-lookup might be more natural, and that the small-code way of doing it might be: - make the lookup into a lambda function (see www.python.org) - map the lambda function down the A<->B list The key step in merge-then-sort is the merge. It would need about 10 lines of horrible ksh. I don't believe there's any natural way of doing it in python. HTH, J. Cone At 15:17 28/07/01 +1000, Jay, Dylan wrote:

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-----Original Message----- From: Casey Duncan [mailto:cduncan@kaivo.com] Sent: Saturday, 28 July 2001 8:14 AM To: Jay, Dylan Cc: 'zope@zope.org' Subject: Re: [Zope] How do I efficiently join catalog results with other data?

"Jay, Dylan" wrote:

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Here is my problem:

I have a dynamic per user map of data about various

objects. I want to do a

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catalog search, combine the results with my other dynamic data and then sort on the dynamic data.

What type of "dynamic data"? Integers, dates, strings, etc?

a tuple of mostly integers and floats.

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Has anyone tried doing this? How do I do it efficiently, still getting the benifits of

low memory usage

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of lazy result sets?

You should make the dynamic data returned from a script and add a field index to the catalog that calls the script. Then you can use the "sort_on" argument to the catalog to sort on the dynamic data.

The set of data is different for every user so this won't work unless I was willing to have a seperate catalog for every user. Having a seperate catalog for each user would be fine if I could combine two to searchs of two different catalogs togeather. and by combine I don't the _plus_ operator you can use for search results. What I need is a relational join, ie only the results from both sets where a certain field has the same value on both.

Someone must have tried to do something like this before?

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