Comments for Benjamin Nevarez

Comment on Database Engine Tuning Advisor and the Query Optimizer – Part 2 by web page search optimization

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Comment on How OPTIMIZE FOR UNKNOWN Works by The Axis Of Evil - SQL Server Blog - SQL Server - Telligent

The Axis Of Evil - SQL Server Blog - SQL Server - Telligent — Wed, 20 Mar 2013 12:03:02 +0000

[...] it’s a batch, a stored procedure, a user defined function or a trigger, the optimizer doesn’t know the values of local variables during query [...]

Comment on Query Optimization Research Papers by Something for the Weekend - SQL Server Links 15/03/13 • John Sansom

Something for the Weekend - SQL Server Links 15/03/13 • John Sansom — Fri, 15 Mar 2013 09:27:28 +0000

[...] Query Optimization Research Papers - A valuable collection of references and good reading from Benjamin Nevarez (Blog|Twitter). [...]

Comment on Query Optimization Research Papers by Query Optimization Research Papers | Philippe TREBAUL on LINKED IN (WORD Press)

Tue, 12 Mar 2013 13:54:50 +0000

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Comment on Statistics on Ascending Keys by Benjamin Nevarez

Benjamin Nevarez — Thu, 07 Mar 2013 23:09:17 +0000

Hi Greg,

Thanks for your comment. I agree that this is not a real world example but the column does not have to be defined as unique, for example in the case of datetime columns. When the column is defined as unique the query optimizer can use the unique constraint to estimate the number of rows to 1 but only in equality comparisons. It won’t be able to get a good estimate for non-equality comparisons when more recent data is added.

Regards,

Ben

Comment on Statistics on Ascending Keys by Greg Linwood

Greg Linwood — Sat, 02 Mar 2013 09:46:10 +0000

Hi Ben
The table used in this example has no candidate / unique key & is therefore not very representative of a real “table”. Incremental keys nearly always have unique constraints (usually Primary Keys) which allow the optimiser to assume cardinality is unique. It might be helpful if you pointed out that this is less relevant where an incremental key has a unique constraint, otherwise readers might think the optimiser is more dependent on statistics than it actually is
Regards,
Greg Linwood

Comment on Statistics on Ascending Keys by Something for the Weekend - SQL Server Links 01/03/13 • John Sansom

Something for the Weekend - SQL Server Links 01/03/13 • John Sansom — Fri, 01 Mar 2013 12:52:09 +0000

[...] Statistics on Ascending Keys - An excellent article on SQL Server statistics from Benjamin Nevarez (Blog|Twitter). Another must read this week folks. [...]

Comment on Statistics on Ascending Keys by Something for the Weekend – SQL Server Links 29/02/13 - SQL Server Blog - SQL Server - Telligent

Fri, 01 Mar 2013 11:04:05 +0000

[...] Statistics on Ascending Keys - An excellent article on SQL Server statistics from Benjamin Nevarez (Blog|Twitter). Another must read this week folks. [...]

Comment on Statistics on Ascending Keys by Benjamin Nevarez

Benjamin Nevarez — Wed, 27 Feb 2013 05:24:20 +0000

Hi Tobi,

That is a good question and I assume the answer is yes as all the information about a single statistics object is stored in a statistics binary large object (statblob).

Ben