Logical Read as a binding standard
Posted: Mon Jan 27, 2025 5:12 am
As already described, these circumstances often lead to the issue of performance being given low priority with regard to the database system. What are possible ways to test database performance reliably and automatically on budget-friendly systems? First of all, when it comes to performance, it is important to move away from concentrating on the measured duration of an operation.
In order to evaluate a T-SQL statement independently of the server size, a unit of measurement other than time for "necessary work" is required. In practice, the unit " logical reads " has proven to be extremely useful for this. Microsoft itself uses this unit in various reports and analyses on database performance. A "logical read" does not mean reading a single data row, but reading a armenia telegram screening database page. Database systems often divide database files into small and equal-sized units. The data of a database system is stored in these units, among other things. A table, for example, consists of a number of database pages. Indexes are also stored in database pages. With Microsoft SQL Server, it can be said that almost every form of data is stored and processed in pages. A database page in SQL Server is always 8kb in size. This value cannot be configured and is therefore a fixed size.
Developers can therefore determine how many 8kb pages had to be read for a T-SQL statement. Since the "logical read" unit is used here, it is irrelevant whether the database page was already in the SQL server's buffer cache or whether it had to be loaded from storage. The value is identical. This removes one prerequisite from the discussion about the size of a test server. It is no longer relevant whether the system has 1.5 TB or "only" 64-128 GB. It is important to understand here that this should not be a license to equip test servers with only 8-16 GB.
In order to evaluate a T-SQL statement independently of the server size, a unit of measurement other than time for "necessary work" is required. In practice, the unit " logical reads " has proven to be extremely useful for this. Microsoft itself uses this unit in various reports and analyses on database performance. A "logical read" does not mean reading a single data row, but reading a armenia telegram screening database page. Database systems often divide database files into small and equal-sized units. The data of a database system is stored in these units, among other things. A table, for example, consists of a number of database pages. Indexes are also stored in database pages. With Microsoft SQL Server, it can be said that almost every form of data is stored and processed in pages. A database page in SQL Server is always 8kb in size. This value cannot be configured and is therefore a fixed size.
Developers can therefore determine how many 8kb pages had to be read for a T-SQL statement. Since the "logical read" unit is used here, it is irrelevant whether the database page was already in the SQL server's buffer cache or whether it had to be loaded from storage. The value is identical. This removes one prerequisite from the discussion about the size of a test server. It is no longer relevant whether the system has 1.5 TB or "only" 64-128 GB. It is important to understand here that this should not be a license to equip test servers with only 8-16 GB.