[Zope-Annce] Annouce RDBTools

[kapil thangavelu]

RDBTools (http://www.zope.org/Members/k_vertigo/Products/RDBTools

 Provides for pythonscript accessible functions to perform set operations on 
zsql method results.

Operations provided

  - union_results

  - join_results

  - difference_results

 The algorithms are based off Aaron Watters kjbuckets package and his early
 1995 news posting to comp.lang.python. 

Example Use Case

 You have correlatable data in multiple dbs. Lets say employee contact info 
is in postgres, and payment info is in oracle. You want to aggregate this 
info into a single result set for a report display. a contrived example but a 
useful illustration.

 contact table:

      create table corp_employee_contacts (
         employee_id   integer unique not null,
         email         varchar(255),
         first_name    varchar(30),
         last_name     varchar(30),
         middle_name   varchar(30)
      );

 payment table:

      create table corp_employee_accounts (
         employee_id   integer unique not null,
         payment_period integer not null,
         payment_amount numeric default 0 not null
      )

 zsql method: getEmployeeContacts:

      select * from corp_employee_contacts

 zsql method: getEmployeeAccounts:

      select employee_id, sum(payment_amount) as total_pay
      from corp_employee_accounts
      group by employee_id

 python script getEmployeeTotalPay:

      from Product.RDBTools import join_results

      contacts = context.getEmployeeContacts()
      accounts = context.getEmployeeAccounts()

      return join_results(accounts, contacts)


 the resultant result set contains properly merged information from both 
results 

Advanced Usage Note

  Acquisition Contexts

   ZSQL Results sets are bound to a context, the set operations exposed here 
   preserve the context of the first result set argument.

  Brains

   brains are not preserved.

  Speed

   additional speed can be had by using installing the kjbuckets extension    
   module, if its not installed the python implementation found in zope will  
   be used.

  Cross Products

   if no common columns are found a cross product is returned.

Author

kapil thangavelu

License

 X11, see LICENSE.txt for more details