SQL Server High Level Architecture

SQL Server high Level Architecture

SQL Server Architecture can be broadly split into following 4 layers and Every query which is submitted to SQL has to go through each of these.

External Protocols -  Client Sends query to SQL server and this query is converted into the form which Relational Engine understands by this component.  After the query is handled by relational engine, the result set/error/warning/exception is sent back to client by this component.

Relational Engine - It parses, compiles, optimizes and executes the query which it get from the protocol layer. While executing the query, it interacts with the storage engine to read/write data.

Storage Engine - Storage Engine manages data access both through transactions and through bulk operations like BCP/Backups/ restores/ DBCC commands etc.

SQL OS - This layer of SQL Server interacts with OS and handles Operating System like tasks - thread management, memory management, deadlock detection, buffer pool management etc.

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