Creating Open Source Projects for Database Code – Ireland Oracle User Group Conference 2020

***UPDATE, 12/04/2020: The conference was postponed indefinitely owing to COVID-19. My presentation will come out in some form at some time. Meanwhile I’m taking the opportunity to update some of my earlier Github projects with improved structure and READMEs.***

I’m speaking on ‘Creating Open Source Projects for Database Code’ at the Oracle User Group Ireland conference 2020 at 4pm on 12 March 2020 in the Gresham hotel, Dublin.

Here’s my abstract:

and here’s the agenda.

Here is a short Twitter thread with a couple of recordings with quick tips on GitHub READMEs: GitHub README tips.

I made a Twitter thread of recordings on my presentation at the 2019 conference: Writing Clean Code in PL/SQL and SQL – Twitter Recordings

#oug_ire #OUGIreland20






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Last October I gave a presentation on database unit testing with utPLSQL, Oracle Unit Testing with utPLSQL. I mentioned design patterns as a way of reducing the effort of building unit tests and outlined some strategies for coding them effectively.

In the current set of articles, I develop the ideas further, starting from the idea that all database APIs can be considered in terms of the axes:

  • direction (i.e. getter or setter, noting that setters can also ‘get’)
  • mode (i.e. real time or batch)

For each cell in the implied matrix, I construct an example API (or view) with specified requirements against Oracle’s HR demo schema, and use this example to construct a testing program with appropriate scenarios as a design pattern. Concepts and common patterns and anti-patterns in automated API testing are discussed throughout, and these are largely independent of testing framework used. However, the examples use my own lightweight independent framework that is designed to help avoid many API testing anti-patterns. The code is available on GitHub here, and includes both framework and design pattern examples: BrenPatF/db_unit_test

In this first example, I present a design pattern for web service ‘save’ procedures by means of a conceptual discussion, together with a working example of base code and unit test code for a procedure to save new employees in Oracle’s well-known HR demonstration schema. The working example can be used as a template for real use cases, and I believe can simplify the development process. It can also be used as a basis for comparing other unit testing frameworks, by implementing the same testing in those frameworks.

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Knapsacks and Numbers

Trying to solve 6 Number 1 target android game using oracle (sql or pl/sql)).

This article provides the SQL that does this, and also a PL/SQL package containing a pipelined function that applies a slightly different algorithm; the latter is also practical, although it proved less efficient on my test problems.

Problem Definition

  • The calculation can be expressed as an additive combination of products
  • Within each product, each number occurs once with a power between -P and +P, including zero
  • All possible products will be considered
  • Each element in the combination has a coefficient between -C and +C, including zero
  • The combination has a fixed number of elements, E
  • The numbers are entered into a table, and a fixed number of them, N, are to be considered
  • The queries are to be generic, parametrised by P, C, E, N, and target value T
  • Integer division is messy, so I use real numbers and exclude non-integral complete products so that the order doesn’t matter
  • (Added 070813:)Optionally, a number can appear in at most one combination, using the BitAnd idea I borrrowed from Stew’s solution

Test Problems

I used two test problems.

Test Problem 1: Brazilian League
The first …


Note that …

SQL Solution with Recursive Subquery Factoring

SQL

Note that currently I have retained the fantasy league table and column names, but they could as well be the generic items and categories in place of players and teams: This is a generic solution.


How It Works

The solution approach is based on the method used to provide exact solutions for knapsack problems in my earlier article, but with a number of extensions to cater for the new category constraints, and to reduce searching to manageable proportions.

Results

Test Problem 1: Brazilian League

The pipelined function solved this in 5 seconds, while the SQL solution solved it in 21 seconds. The solutions were identical, as follows:


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Conclusions

My idea for using recursive subquery factoring to solve combinatorial optimisation problems, such as knapsack problems, described in other articles on my blog, was previously only practical for small problems. The extensions described here render it a practical proposition even for larger problems. It is also relatively simple compared with procedural approaches.







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