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In our earlier discussion about non clustered index ,we have seen that, the leaf level of a non clustered index contain only the non clustered index key column and clustered index key (if the table is a clustered table). To fetch the remaining colum...
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In our earlier post, we have discussed about the non clustered index, but there we were always discussing about unique non clustered index to make the discussion simple.As we understood the general structure of the non clustered index, let us discu...
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In SQL server, there are two types of table based on the storage.A table with clustered index is called Clustered Table and a table with out a clustered index is called Heap Table. In earlier post, we have discussed about the specialty and the storag...
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In the last post, we have discussed about non clustered index on a clustered table.In this post we will discuss about the non clustered index on a heap table.
Non clustered index can be created on clustered table as well as heap table.While creat...
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A table can have only one clustered index as the data rows are stored in the order of the clustered key, but a table can have multiple non clustered indexes.We have discussed about clustered index structure in our earlier post . In this post let us t...
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In my earlier post, we have discussed about Data,GAM,SGAM and PFS pages. In this post, let us try to understand about the IAM (Index Allocation Map) page.
In SQL server 2005 and later, there are three types of allocation units.
IN_ROW_DATA (bt...
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In the earlier post we tried to understand the difference between a table having clustered index and does not have a clustered index. A table with clustered index is called clustered table.A table with out clustered index is called a heap table.
Heap Ta...
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In my earlier post, we have discussed about GAM and SGAM Page and Data Page. In this postlet us discuss about the Page Free Space (PFS) page.
PFS page is the second page (Page Number 1) in the data file followed by file header (Page Number 0). GAM ...
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We know that SQL server stores the data in 8 KB pages. An extent is made up of 8 physically contiguous pages.When we create a database, the data files will be logically divided into the pages and extents.Later, when user objects are created, the page...
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In our last post, we have gone through the data page structure and we have noticed that there is an overhead of 7 bytes in each records. Let us try to understand how SQL Server stores the records in a data pages.
Data record stores actual data. In...
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