Data Pages In MsSqlServer and Extents

Types of Extent.

1) Uniform Extent:- IN This a Single extent only single object info is stored.

2) Mixed Extent :- (Is Also Single Extent) In a Single extent multiple objects info can be stored, but not more than 8 objects.

Definition of Pages.

1) Data Page :- Store Info about other data types except text and image.

2) Text/Image Pages :- In this large memory objects pages are stored.

3) Global Allocation Map: – This gives the information regarding which extent is used or which extent is free. This gives info in bits or 0 and 1.

0 indication of used extent

1 indication of free extent

1 global allocation map is equal to 64000 extent

Approximate 4gb of data can be stored in global allocation map

4) Index Allocation Map :- This gives the info regarding action which extent is used for which purpose. I.e. Which extent is used for which object and which type of data is stored in these extent.

5) Index Pages :- It is used to store index info.

6) Page free space pages :- It is used to store info of free pages i.e. the pages which are not used.

1 Page free space page  is equal to 8000 page free info

We can store 8000 free page info in  1 page free space.

Remembering Note

  • Number of Instance that can be Formed by Sql Server are 32767 Instances.
  • One Instance can create 32767 Database  of SQL Server.
  • Master Database Store Path of Datafile of User Defined Database.
  • File Groups used for Permissions to Database.
  • We Can Store Datafiles at different Path With the Help of FileGroup and maximum 32767 File group can be made.
  • One Data File can Store 16TB Data
  • 1 Log File Size or Datasotrage Capacity will be 2TB
  • Database Name Can’t be exceeded  from 128 characters
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