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Ian Jose's WebLog

This weblog is intended to help T-SQL developers get the best performing query plans from SQL Server. Some of the posts describe simple mistakes that can be easily avoided. Other posts describe complex solutions to limitations in SQL Server. Lastly, so

Ascending Keys and Auto Quick Corrected Statistics

A common problem for some SQL Server applications are cases where data typically ascends. For...

Date: 04/24/2006

Query Processor Modelling Extensions in SQL Server 2005 SP1

Trace flag 2301, available in SQL Server 2005 SP1, enhances the modelling ability of the query...

Date: 04/24/2006

Disabling Constant-Constant Comparison Estimation

SQL Server 8.0 did not perform cardinality estimates based on the comparion of two constants....

Date: 03/28/2006

Make Functions Schema-bound

Create user defined functions with the SCHEMABINDING clause where possible. In the absence of this...

Date: 01/31/2006

Regularly Update Statistics for Ascending Keys

Ascending key columns, such as IDENTITY columns or datetime columns representing real-world...

Date: 11/10/2005

Create Statistics for All Union Inputs

When a query requires statistics on the result of a UNION or UNION ALL operation, create needed...

Date: 11/10/2005

Create Multi-Column Statistics

When a query has a multi-column condition, consider creating multi-column statistics if you suspect...

Date: 11/10/2005

Auto-create and Auto-update Statistics

For a large majority of SQL Server installations, the most important best practice is to use auto...

Date: 11/10/2005

Simplify statements with IF

In some cases, a SQL statement can be simplified by using procedural logic. Instead of issuing one...

Date: 11/10/2005

Limit Use of Multi-Statement TVFs and Table Variables

Limit use of multi-statement table valued functions (TVFs) and table variables in situations where...

Date: 11/10/2005

Use Condition-Specific Stored Procedures

The optimizer chooses the best plan for an SP given the current parameter values. This plan is then...

Date: 11/10/2005

Use Function Results

Built-in functions with literal constant inputs are simplified during optimization to resultant...

Date: 11/10/2005

Limit Non-order Preserving Expressions

Expressions with column transformations that do not retain the original column order do not benefit...

Date: 11/10/2005

Avoid Unnecessary Data Type Conversions

SQL Server adds implicit data type conversions when types don’t match. This can have unintended...

Date: 11/10/2005

Use Parameters or Literals for Query Inputs

Use unmodified parameters or literal constants in query statements to ensure that the optimizer can...

Date: 11/10/2005