STRUCTURE OF DATA PAGE IN SQL SERVER / DATA PAGES

Data pages in sql server are used to store actual data.The disk
space allocated to a data file (.mdf or .ndf) in a database is
logically divided into pages numbered contiguously from 0 to n. Disk
I/O operations are performed at the page level.

In SQL Server, the page size is 8 KB.

Structure of the Data pages in Sql Server is given below.

1.PAGE HEADER – Each page has a 96-byte header. This is used to
store system information about the page. This information includes the
page number, page type, the amount of free space on the page, and the
allocation unit ID of the object that owns the page.

2.ACTUAL DATA ROWS – Data rows contains actual data.They are put on the page serially, starting immediately after the header.

3.ROWS OFFSET / ROW POINTERS – A row offset table starts at the end
of the page, and each row offset table contains one entry for each row
on the page. Each entry records how far the first byte of the row is
from the start of the page. The entries in the row offset table are in
reverse sequence from the sequence of the rows on the page. This means
the entries are from right to left.

Pawan Kumar

Pawankkmr@hotmail.com

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