SQL Server Architecture - SQL Server 2012 Internals and Troubleshooting - page 15

6.

The Access Methods needed to read a page from the database to complete the request from
the Query Executor and asked the Buffer Manager to provision the data page.

7.

The Buffer Manager checked the data cache to see if it already had the page in cache. It
wasn't in cache so it pulled the page from disk, put it in cache, and passed it back to the
Access Methods.

8. Finally, the Access Methods passed the result set back to the Relational Engine to send to

the client.

Query Tree Language Event

Cmd Parser TDS

TDS

Query Plan SQL Server

Network Interface

Optimizer Query Executor SNI

Protocol
Layer

Relational Engine

Plan Cache

OLE DB

Access Methods

Data Cache

Data file

Bufer
Manager

Storage Engine Bufer Pool

FIGURE 1-5

A Simple Update Query
Now that you understand the life cycle for a query that just reads some data, the next step is to
determine what happens when you need to write data. To answer that, this section takes a look at a
simple UPDATE query that modii es the data that was read in the previous example.