Update Statistics Before Rebuilding Indexes

Sql Server Statistics Vs Index Rebuild Which Matters More — SQL Server Statistics vs Index Rebuild Which Matters More

When users report that queries have suddenly become slow, many DBAs immediately rebuild indexes.

A better first step is often to check whether statistics are outdated.

The SQL Server Query Optimizer relies on statistics to estimate row counts and choose the best execution plan. If statistics are stale, SQL Server may choose an inefficient plan even when indexes are perfectly healthy.

Short Explanation

Statistics contain information about the distribution of data in a table or index.

As data changes over time through inserts, updates, and deletes, statistics can become outdated.

Refreshing statistics gives the optimizer a more accurate picture of the data, allowing it to generate better execution plans.

You can update statistics for a database using:

EXEC sp_updatestats;

Or update statistics for a specific table:

UPDATE STATISTICS dbo.Orders;

Real-World Example

An e-commerce database experienced a spike in orders during a holiday sale.

Although indexes were healthy, a key sales report slowed from 3 seconds to 45 seconds.

The issue wasn’t index fragmentation—it was outdated statistics after millions of new rows had been added.

Running sp_updatestats allowed SQL Server to generate a better execution plan, reducing execution time back to under 4 seconds without rebuilding a single index.