article about reports

Gemfile

@@ -1,7 +1,6 @@
 # frozen_string_literal: true
 
 source "https://rubygems.org"
-
 gemspec
 
 

_posts/2022-08-21-how-to-build-complex-reports.md

@@ -0,0 +1,107 @@
+---
+layout: post
+title: Performance issues in business reporting
+subtitle: How not to kill the database
+tags: [linq,database,performance,reporting]
+---
+
+I love performance tasks. For obvious reasons, I immediately see the benefits of optimizations. Or the disappointment
+when something goes wrong.
+
+Reporting is usually complex and stressful for a database or other data source. It happens because.
+A report is very often compiled from aggregated data. This means that in almost every case we have to pull data from many
+database tables. And we use JOINs for this task.
+
+Queries are often very complex and long and sometimes hard to understand.
+
+This causes deadlocks, slows down the database and last but not least it impacts the work of the end users.
+
+Of course, you can and probably should have a dedicated database for reporting. Let's clone a production database
+synchronized somehow.
+
+But... it costs something. And the client will push you to reduce maintenance and operational costs.
+
+Another downside is the time it takes to create a report. So common practice is to run nightly jobs.
+To create a report for a previous time period (day, week, month...).
+
+It's not on demand.
+
+So what is the solution.
+
+
+## Idea
+
+My idea is to build the report incrementally using events. This means that if the report data changes,
+the system sends an event (hey, something has changed) and the reporting engine processes the event and modifies the current report.
+
+## Demo
+
+Let's dive into the example. It's the very trivial business activity app. Mainly it allows to store individual business cases,
+especially the name of the salesman, the product he sold, the number of units, the total price, the date of sale.
+
+Finally, we need a weekly overview of sales activity, especially which salesman have been most successful. For a reward.
+The weekly report is a simple table with Year, Week, Best Agent, Most Sold Product, Quantity and Amount. 
+So It's a weekly history of successful traders.
+
+Components:
+- Departments
+- Agents
+- Products
+- Sales Log
+- Weekly Report
+- History
+
+I've used Bogus (Faker) for random data like Departments, Agents and Products.
+
+## How it works
+
+You can try to add a business case. Open the Sales Log, select the agent, product, enter the quantity, adjust the total price and date
+and finally hit the Add log button. That's it.
+
+The app is using CQRS pattern. So the request is producing command _AddSalesLogCommand_. It ensures that your data
+will be stored into the database.
+
+And also, if the storing is successful, it is firing event _SalesLogAddedEvent_.
+
+Handler for this event, does this in this order:
+- check if there is a weekly report for the week when this business case occurred, if there is not, create a report and bail out.
+
+``` csharp
+if (reportWeek is null)
+{
+  await CreateReport(request, requestWeek, requestYear, requestAgent, requestProduct, cancellationToken);
+  return;
+}
+```
+
+- check if the total price of this case is better than the winner of the week, if so, update the report.
+
+``` csharp
+if (reportWeek.TotalPrice < request.Price)
+{
+   // update report with new max
+   await UpdateReport(reportWeek, requestAgent.FirstName + " " + requestAgent.LastName,
+   requestAgent.SalesAgentId, requestProduct.Name, request.Quantity, request.Price, cancellationToken);
+   return;
+}
+```
+
+- worst case scenario, recount the entire week and find a winner again.
+
+``` csharp
+  var winner = await GetBestSalesmanOfWeek(requestWeek, requestYear, cancellationToken);
+  await UpdateReport(reportWeek, winner.Agent, winner.AgentId, winner.Product, winner.TotalProducts, winner.TotalPrice, cancellationToken);
+```
+
+## Conclusion ##
+
+This example is only a proof-of-concept.
+
+It has never been used in reality on complex reports. I have not verified that it works in real-word scenario,
+it is maintainable, understandable for programmers and overall more convenient than the classic solution.
+
+Still, if anyone is brave enough to try it, let me know how the result was and what advantages and disadvantages they encountered.
+
+## Source Code ##
+
+[Source code](https://github.com/patriksima/EventCachingDemo) is hosted by Github.

beautiful-jekyll-theme.gemspec

@@ -2,7 +2,7 @@
 
 Gem::Specification.new do |spec|
   spec.name          = "beautiful-jekyll-theme"
-  spec.version       = "5.0.0"
+  spec.version       = "6.0.1"
   spec.authors       = ["Dean Attali"]
   spec.email         = ["[email protected]"]
 
@@ -17,11 +17,12 @@ Gem::Specification.new do |spec|
     "documentation_uri" => "https://github.com/daattali/beautiful-jekyll#readme"
   }
 
-  spec.add_runtime_dependency "jekyll", "~> 3.8"
+  spec.add_runtime_dependency "jekyll", "~> 3.9.3"
   spec.add_runtime_dependency "jekyll-paginate", "~> 1.1"
   spec.add_runtime_dependency "jekyll-sitemap", "~> 1.4"
   spec.add_runtime_dependency "kramdown-parser-gfm", "~> 1.1"
-  spec.add_runtime_dependency "kramdown", "~> 2.3.0"
+  spec.add_runtime_dependency "kramdown", "~> 2.3.2"
+  spec.add_runtime_dependency "webrick", "~> 1.8"
 
   spec.add_development_dependency "bundler", ">= 1.16"
   spec.add_development_dependency "rake", "~> 12.0"