Points to check before any data migration...

Ancient world

• 1950s – Compilers will make programmers obsolete
• 1960-70s - 3rd generation programming languages will reduce programmer shortages

...

Middle Ages

• 1980s - 4rd generation programming languages and CASE tools will definitely reduce programmer shortages
• 1980s – client server SQL DBMS will solve mainframe “vendor lock”
• 1990s – 3-tiers architecture will solve DBMS “vendor lock …

Comparing SQL Server and Redis performance

DBMS market share trends of last decade by Gartner on the big picture

The frequently asked problem on interviews.

You have a log of some user activities represented as a table. Every activity record has at least users ID and activity date/time values.

The session is a sequence of activities having less than N minutes between two log records. When the elapsed …

Very old subject I remember to discuss in the middle of 1990s... But some people still says that a clean architecture should remove all business logic from the database.

Let's start from referential and domain integrity rules (constraints). Are they business ones? Yes, of course. The e-mail column should be …

The opaque pointer (pimpl) idiom has been inherited from C language where it is used to encapsulate implementation details. However, both old-school and "modern" C++ dispense you from writing some ugly code, and allow to use interfaces with object factories.

The example of implementation with both pimpl and interface approach …

How to extract all combinations (unordered subsets) from a given set in C++?

Let us estimate the count before. Suppose N is the size of a given set, and K is the number of elements in the subset. The count of all combinations (unordered subsets) of size K is

C …

Suppose a string of ordered cyphers 123456789. You can insert signs "+" and "-" between any cyphers to make a correct arithmetical expression. The problem is to find all expressions which sum is 100.

This problem may be interesting for dynamic script languages having the function of a string expression evaluation.

E …

Unlike Java or C#, the C++ world does not have a unified coding standard. The naming convention is still the choice of programmer teams or enterprises.

However, there are several standards widely used in the software industry.

• C++ standard library related code conventions
  • GCC Coding Conventions
  • ISO C++ coding standards …