DBMS/Storage Manager

Storage manager module of the database provides the interface between the following component:

• data stored in the database
• the application programs
• queries submitted to the system

Components of a Storage Manager

file manager

function of the file manager is to manage disk space for storage and manage data structure used for storing information.

buffer manager

The buffer manager reads disk pages into a main memory page as needed. The collection of main memory pages (called frames) used by the buffer manager for this purpose is called the buffer pool. This is just an array of Page objects. The buffer manager is used by (the code for) access methods, heap files, and relational operators to read / write /allocate / de-allocate pages. The Buffer Manager makes calls to the underlying DB class object, which actually performs these functions on disk pages.

Replacement policies for the buffer manager can be changed easily at compile time.

Authorisation and integrity manager

Checks the authorization of users to access data and tests integrity constraints

Indexing and hashing

Many queries reference only a small proportion of records in a file. For example, finding all records at Perryridge branch only returns records where bname = ``Perryridge. We should be able to locate these records directly, rather than having to read every record and check its branch-name. We then need extra file structuring.

Evaluation

As we know that, computer has two storage memories 1.primary storage 2.secondary storage