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inbs
Aged Yak Warrior
860 Posts |
 Posted - 2010-09-16 : 14:14:12
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| i do not understand how i can estimate the number of pages in index?what is it mean?"Pages Scanned: If you know the approximate row size and the number of rows contained in your table or index, you can estimate the number of pages there should be in that index"[url]http://www.sql-server-performance.com/articles/per/index_fragmentation_p2.aspx[/url] |
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russell
Pyro-ma-ni-yak
5072 Posts |
Posted - 2010-09-16 : 15:05:00
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| A page is the basic storage unit of SQL Server data. It is 8 KB. |
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inbs
Aged Yak Warrior
860 Posts |
Posted - 2010-09-16 : 15:37:29
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| so how i know how many pages i have in the index/table? |
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russell
Pyro-ma-ni-yak
5072 Posts |
Posted - 2010-09-16 : 18:56:28
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| to get a rough estimate, add up the bytes of the data types. divide into 8192. there are 192 bytes of overhead in each page so divide by 8,000.for example, int = 4 bytes. if you index an int and don't include any other columns, you can fit about 2000 per page.that assumes full pages of course |
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SwePeso
Patron Saint of Lost Yaks
30421 Posts |
Posted - 2010-09-17 : 04:45:40
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You can use 8,060 bytes per page.Is the index clustered or non-clustered?1) Multiply this number with your current fill factor.2) Divide by byte width for all key columns in index.3) Now you roughly have the number of pages (lower count). Nullability for columns in index may take some extra overhead.
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estimate the number of pages in index