Motivation

C++11 has introduced the move semantic which can also be used in containers instead of "old-school" pointers. The specific containers owning objects has been proposed earlier by third-party libraries like Boost (for example, ptr_map or ptr_vector).

Local temporary tables are isolated in the scope of current session regardless its name. It means that #temp_table in the session 1 is not the same that #temp_table in the session 2. However, the names of constraints are stored in the metadata of tempdb and can produce duplicate name errors.

Hash indexes are used as entry points for memory-optimized tables; both features were introduced in SQL Server 2014. Let's look at index performance in scenario "key-value store".

Scenario and environment

The table stores a significant volume (about 10 millions rows) of pairs key-value. The key is of integer type and the value is a small random string.

The table store is used :

• random read of a value from a key
• random update of a value by a key

We will tests the scenario for the following types of table :

Collection of methods to generate random string in a single SQL statement

M1: Recursive string concatenation

On SQL Server the method is limited by 100 characters owing to the recursion level limitation. The method has the performance issues when using in loops/joins because the table always have 100 rows generated every time.