SQLServerCentral.com Articles tagged statistics

Managing SQL Server Statistics

Mon, 15 Apr 2013 06:00:00 UT

Accurate statistics about the data held in tables are used to provide the best execution strategy for SQL queries. but if the statistics don't accurately reflect the current contents of the table you'll get a poorly-performing query. How do you find out if statistics are correct, and what can you do if the automatic update of statistics isn't right for the way a table is used?

SQL Server Statistics Questions We Were Too Shy to Ask

Tue, 12 Mar 2013 06:00:00 UT

If you need to optimise SQL Server performance, it pays to understand SQL Server Statistics. Grant Fritchey answers some frequently-asked questions about SQL Server Statistics: the ones we somehow feel silly asking in public, and think twice about doing so.

SQL Server Statistics Questions We Were Too Shy to Ask

Fri, 01 Mar 2013 07:00:00 UT

Free Webinar: Statistics in Oracle and SQL Server

Tue, 22 Jan 2013 07:00:00 UT

In their third live 'Oracle vs. SQL Server' discussion, Jonathan Lewis (Oracle Ace Director, OakTable Network) and Grant Fritchey (Microsoft SQL Server MVP) will look at statistics in Oracle and SQL Server. Expect a lively debate on Oracle vs. SQL Server from two leading RDBMS experts on Jan 23, 2013.

Free Webinar: Statistics in Oracle and SQL Server

Tue, 22 Jan 2013 07:00:00 UT

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Free Webinar: Statistics in Oracle and SQL Server

Tue, 22 Jan 2013 07:00:00 UT

Free Webinar: Statistics in Oracle and SQL Server

Tue, 22 Jan 2013 07:00:00 UT

How to Find Outdated Statistics in SQL Server 2008

Thu, 06 Sep 2012 06:00:00 UT

How can I find out which statistics are outdated in my SQL Server database?

Tips to optimize your SQL statements

Fri, 10 Feb 2012 07:00:00 UT

Don't blame SQL Server if your SQL Statements perform badly! But where do you start to investigate the problem? This article is a primer on were to start looking when your SQL runs slowly.

Statistics on Ascending Columns

Fri, 16 Sep 2011 06:00:00 UT

It comes as rather a shock to find out that one of the commonest circumstances in an OLTP database, an ascending primary key with most querying on the latest records, can throw the judgement of the Query Optimiser to the extent that perfomance nose-dives. Fabiano Amorim once again dons snorkel and goggles to explore the murky depths of execution plans to find out why.

Questions About SQL Server Distribution Statistics

Wed, 13 Jul 2011 06:00:00 UT

Fabiano Amorim was asked a couple of questions about SQL Server Distribution Statistics. Having given an answer based on his current knowledge, he then decided to find out for himself whether what he'd said was right, and started an epic journey of exploration into Distribution Statistics and the way that the Query Optimiser uses them.

Questions About SQL Server Distribution Statistics

Tue, 12 Jul 2011 06:00:00 UT

Automatic Statistics Update Slows Down SQL Server 2005

Fri, 25 Feb 2011 07:00:00 UT

I have a database which has several tables that have very heavy write operations. These table are very large and some are over a hundred gigabytes. I noticed performance of this database is getting slower and after some investigation we suspect that the Auto Update Statistics function is causing a performance degradation.

SQL Server Statistics: Problems and Solutions

Thu, 11 Nov 2010 07:00:00 UT

SQL Server Statistics assist the query optimiser to calculate the best way of running the query. Holger describes every common way that things can go wrong with statistics, and how to put matters right.

Introduction to SQL Server Statistics

Fri, 03 Sep 2010 06:00:00 UT

A free virtual chapter presentation by Andy Warren on Sept 7, 2010 at 12:00EDT. This beginner to intermediate level session will introduce you to statistics, including how to create, manage, troubleshoot, and more!

How Old Are Your Database Statistics?

Thu, 02 Sep 2010 06:00:00 UT

Unlike fine wine, database statistics do not improve with age. I recently helped out with a client who was having...

Tips to optimize your SQL statements

Fri, 10 Feb 2012 07:00:00 UT

Don't blame SQL Server if your SQL Statements perform badly! But where do you start to investigate the problem? This article is a primer on were to start looking when your SQL runs slowly.

13 Things You Should Know About Statistics and the Query Optimizer

Tue, 02 Feb 2010 07:00:00 UT

Fabiano launches into a sound technical explanation of the way that the query optimiser works in SQL Server with a mention of Brazilian Soccer stars and young ladies on Copacabana beach. You'll never quite think of statistics, execution plans, and the query optimiser the same way again after reading this, but we think you'll understand them better.

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Index Primer - Just what statistics are kept?

Wed, 28 Oct 2009 06:00:00 UT

An in-depth look at index statistics and how they are used by the optimizer by Josef Richberg.

Collecting Query Statistics for SQL Server 2005

Mon, 05 Oct 2009 06:00:00 UT

With SQL Server 2005 DMVs, we can easily find query performance statistics. Every DBA has a favorite script to find query performance stats. I also have one. But, are all the queries captured by the DMVs? In this tip I will walk through capturing some of this data and show what is capture and what is not captured by the DMVs.

Statistics Used by the Query Optimizer in Microsoft SQL Server 2008

Fri, 24 Jul 2009 06:00:00 UT

Microsoft SQL Server 2008 collects statistical information about indexes and column data stored in the database. These statistics are used by the SQL Server query optimizer to choose the most efficient plan for retrieving or updating data. This paper describes what data is collected, where it is stored, and which commands create, update, and delete statistics. By default, SQL Server 2008 also creates and updates statistics automatically, when such an operation is considered to be useful. This paper also outlines how these defaults can be changed on different levels (column, table, and database).

Retaining historical index usage statistics for SQL Server - Part 2

Wed, 24 Jun 2009 06:00:00 UT

We look at performing the same task for the sys.dm_db_index_operational_stats Dynamic Management Function (or DMF.) The process is identical, the code is however quite different due to the structural differences between sys.dm_db_index_usage_stats and sys.dm_db_index_operational_stats.

Retaining historical index usage statistics for SQL Server

Tue, 26 May 2009 06:00:00 UT

In this three-part series I'll look at what you can do to persist this data so you don't find yourself waiting for usage stats to compile over a reasonable period of time just so you can harness the power of the indexing DMOs in your performance tuning process.

Index Metadata and Statistics Update Date for SQL Server

Tue, 12 Aug 2008 06:00:00 UT

Statistics update date is stored as metadata on the SQL instance, but after a great deal of research against the system tables and DMVs I realized that this information is not readily exposed to the DBA via any other method than the STATS_DATE() function or the SQL Server Management Studio graphical user interface (GUI).

Rebuilding Stats: Twice or Not At All

Tue, 29 Jul 2008 06:00:00 UT

Are you rebuilding statistics twice on your tables? Longtime expert, Andy Warren, shows why you might be asking more work of your SQL Server than is required.

Statistics and Indexes

Tue, 11 Mar 2008 06:00:00 UT

When is it okay to let SQL Server to make a statistic for columns in your queries, and when should you take those statistics and make an index out of them? What I do is to test all of my procs, and if they generate system statistics (_WA_SYS%), then I add an index to the table for the column in the statistic. But is this a good practice?

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