Update statics

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Update statics

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jitendra.padhiyar

Posted Monday, January 07, 2013 11:36 PM

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Hello Masters,

What exactly "Update static" is ? Is it just removing fragmentation from database that is created by DML queries? Is it making any changes to indexes ? and for all the updatation is it using Tempdb or any other database ?

Please explain in detail to understand me.

Thanks in advance.

Jitendra

Post #1403985

Arjun Sivadasan

Posted Tuesday, January 08, 2013 12:33 AM

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It is not static. UPDATE STATISTICS updates the statistics that SQL Server stores for a table.

define: Statistics - The practice or science of collecting and analyzing numerical data in large quantities.

Statistics help query optimizer to choose which index to use. SQL Server may store statistics for indexes or columns.

Try this: DBCC SHOW_STATISTICS(tablename, statisticobjname)

Statistics for a table is usually manually updated after a bulk insert operation because the statistics could have become stale. A bulk insertion should cause an auto update, but sometimes this takes time, causing bad performance.

Read more:
http://msdn.microsoft.com/en-us/library/ms174384.aspx

Post #1403999

jitendra.padhiyar

Posted Tuesday, January 08, 2013 12:39 AM

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Thanks a lot Arjun !

You explain me what exactly statisc is and what the sql server doing during update statics. Can you pls clear my more doubts?

1. Is it using indexing and sorting for this process ?
2. Is it using TempDB for data collection (for static purpose) ?

Thnx in advance,

Jitendra

Post #1404003

Bhuvnesh

Posted Tuesday, January 08, 2013 12:46 AM

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jitendra.padhiyar (1/8/2013)

1. Is it using indexing and sorting for this process ?
2. Is it using TempDB for data collection (for static purpose) ?

NO.

Have you read the link which arjun posted ?

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Post #1404005

Bhuvnesh

Posted Tuesday, January 08, 2013 12:52 AM

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see this link too Statistics

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Post #1404007

Grant Fritchey

Posted Wednesday, January 09, 2013 4:55 AM

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jitendra.padhiyar (1/8/2013)

1. Statistics are a very small data set representing the selectivity/density and the histogram, or distribution, of the first column of the data defined by the statistic. This is true if it's on an index or just a set of statistics created automatically on a column referenced in a filtering clause in T-SQL code. It doesn't rearrange data, so no sorting is done. It does read the data, either in a sampled fashion, or by scanning the entire table for the column(s) defined by the statistic. Statistics are part of indexes, but they are separate from them.
2. Just about every process hits tempdb to one degree or another. I wouldn't be surprised if this one does too. But, again, the statistics are a very small data set, 200 rows, so updating them usually is not a major process unless we're talking hundreds of millions of rows of data.

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