Updating statistics sql server

Typically, the default sampling ratio is enough to generate good execution plans. For example, my colleagues and I once had a large table with approximately 12 million records in the table.

The number of records in the table was fairly static.

The sp_updatestats procedure has the same effect as running the UPDATE STATISTICS command using the ALL keyword.

The exception is that the sp_updatestats procedure checks the internal system tables and looks to see if the table needs its statistics updated. In addition to updating the statistics on user tables, the procedure also checks system tables for stale statistics and the statistics are updated as needed.

By default, statistics are compiled based on a sampling of the data in the table.

The sampling amount varies depending on the size of the table, but it can be as little as just a few percent to as much as 100% of the table.

We decided to start updating the statistics using the FULLSCAN flag.

are metadata about the data within a table and they're created and updated on a column-by-column basis, not on the entire table.

The database engine employs statistics when generating execution plans that are used to access data stored within the database.

Even worse, it would perform a table scan instead of any index operation at all.

Auto create statistics and auto update statistics Each database has two options related to statistics: auto create statistics and auto update statistics.

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